text: /*
   * Copyright (c) 1999, 2021, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2012, 2020 SAP SE. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   *
   */
  
  // According to the AIX OS doc #pragma alloca must be used
  // with C++ compiler before referencing the function alloca()
  #pragma alloca
  
  // no precompiled headers
  #include "jvm.h"
  #include "classfile/vmSymbols.hpp"
  #include "code/icBuffer.hpp"
  #include "code/vtableStubs.hpp"
  #include "compiler/compileBroker.hpp"
  #include "interpreter/interpreter.hpp"
  #include "jvmtifiles/jvmti.h"
  #include "logging/log.hpp"
  #include "logging/logStream.hpp"
  #include "libo4.hpp"
  #include "libperfstat_aix.hpp"
  #include "libodm_aix.hpp"
  #include "loadlib_aix.hpp"
  #include "memory/allocation.inline.hpp"
  #include "misc_aix.hpp"
  #include "oops/oop.inline.hpp"
  #include "os_aix.inline.hpp"
  #include "os_share_aix.hpp"
  #include "porting_aix.hpp"
  #include "prims/jniFastGetField.hpp"
  #include "prims/jvm_misc.hpp"
  #include "runtime/arguments.hpp"
  #include "runtime/atomic.hpp"
  #include "runtime/globals.hpp"
  #include "runtime/globals_extension.hpp"
  #include "runtime/interfaceSupport.inline.hpp"
  #include "runtime/java.hpp"
  #include "runtime/javaCalls.hpp"
  #include "runtime/mutexLocker.hpp"
  #include "runtime/objectMonitor.hpp"
  #include "runtime/os.hpp"
  #include "runtime/osThread.hpp"
  #include "runtime/perfMemory.hpp"
  #include "runtime/safefetch.inline.hpp"
  #include "runtime/sharedRuntime.hpp"
  #include "runtime/statSampler.hpp"
  #include "runtime/thread.inline.hpp"
  #include "runtime/threadCritical.hpp"
  #include "runtime/timer.hpp"
  #include "runtime/vm_version.hpp"
  #include "services/attachListener.hpp"
  #include "services/runtimeService.hpp"
  #include "signals_posix.hpp"
  #include "utilities/align.hpp"
  #include "utilities/decoder.hpp"
  #include "utilities/defaultStream.hpp"
  #include "utilities/events.hpp"
  #include "utilities/growableArray.hpp"
  #include "utilities/vmError.hpp"
  
  // put OS-includes here (sorted alphabetically)
  #include <errno.h>
  #include <fcntl.h>
  #include <inttypes.h>
  #include <poll.h>
  #include <procinfo.h>
  #include <pthread.h>
  #include <pwd.h>
  #include <semaphore.h>
  #include <signal.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <string.h>
  #include <unistd.h>
  #include <sys/ioctl.h>
  #include <sys/ipc.h>
  #include <sys/mman.h>
  #include <sys/resource.h>
  #include <sys/select.h>
  #include <sys/shm.h>
  #include <sys/socket.h>
  #include <sys/stat.h>
  #include <sys/sysinfo.h>
  #include <sys/systemcfg.h>
  #include <sys/time.h>
  #include <sys/times.h>
  #include <sys/types.h>
  #include <sys/utsname.h>
  #include <sys/vminfo.h>
  
  // Missing prototypes for various system APIs.
  extern "C"
  int mread_real_time(timebasestruct_t *t, size_t size_of_timebasestruct_t);
  
  #if !defined(_AIXVERSION_610)
  extern "C" int getthrds64(pid_t, struct thrdentry64*, int, tid64_t*, int);
  extern "C" int getprocs64(procentry64*, int, fdsinfo*, int, pid_t*, int);
  extern "C" int getargs(procsinfo*, int, char*, int);
  #endif
  
  #define MAX_PATH (2 * K)
  
  // for timer info max values which include all bits
  #define ALL_64_BITS CONST64(0xFFFFFFFFFFFFFFFF)
  // for multipage initialization error analysis (in 'g_multipage_error')
  #define ERROR_MP_OS_TOO_OLD                          100
  #define ERROR_MP_EXTSHM_ACTIVE                       101
  #define ERROR_MP_VMGETINFO_FAILED                    102
  #define ERROR_MP_VMGETINFO_CLAIMS_NO_SUPPORT_FOR_64K 103
  
  // excerpts from systemcfg.h that might be missing on older os levels
  #ifndef PV_7
    #define PV_7 0x200000          /* Power PC 7 */
  #endif
  #ifndef PV_7_Compat
    #define PV_7_Compat 0x208000   /* Power PC 7 */
  #endif
  #ifndef PV_8
    #define PV_8 0x300000          /* Power PC 8 */
  #endif
  #ifndef PV_8_Compat
    #define PV_8_Compat 0x308000   /* Power PC 8 */
  #endif
  #ifndef PV_9
    #define PV_9 0x400000          /* Power PC 9 */
  #endif
  #ifndef PV_9_Compat
    #define PV_9_Compat  0x408000  /* Power PC 9 */
  #endif
  
  
  static address resolve_function_descriptor_to_code_pointer(address p);
  
  static void vmembk_print_on(outputStream* os);
  
  ////////////////////////////////////////////////////////////////////////////////
  // global variables (for a description see os_aix.hpp)
  
  julong    os::Aix::_physical_memory = 0;
  
  pthread_t os::Aix::_main_thread = ((pthread_t)0);
  int       os::Aix::_page_size = -1;
  
  // -1 = uninitialized, 0 if AIX, 1 if OS/400 pase
  int       os::Aix::_on_pase = -1;
  
  // 0 = uninitialized, otherwise 32 bit number:
  //  0xVVRRTTSS
  //  VV - major version
  //  RR - minor version
  //  TT - tech level, if known, 0 otherwise
  //  SS - service pack, if known, 0 otherwise
  uint32_t  os::Aix::_os_version = 0;
  
  // -1 = uninitialized, 0 - no, 1 - yes
  int       os::Aix::_xpg_sus_mode = -1;
  
  // -1 = uninitialized, 0 - no, 1 - yes
  int       os::Aix::_extshm = -1;
  
  ////////////////////////////////////////////////////////////////////////////////
  // local variables
  
  static volatile jlong max_real_time = 0;
  static jlong    initial_time_count = 0;
  static int      clock_tics_per_sec = 100;
  
  // Process break recorded at startup.
  static address g_brk_at_startup = NULL;
  
  // This describes the state of multipage support of the underlying
  // OS. Note that this is of no interest to the outsize world and
  // therefore should not be defined in AIX class.
  //
  // AIX supports four different page sizes - 4K, 64K, 16MB, 16GB. The
  // latter two (16M "large" resp. 16G "huge" pages) require special
  // setup and are normally not available.
  //
  // AIX supports multiple page sizes per process, for:
  //  - Stack (of the primordial thread, so not relevant for us)
  //  - Data - data, bss, heap, for us also pthread stacks
  //  - Text - text code
  //  - shared memory
  //
  // Default page sizes can be set via linker options (-bdatapsize, -bstacksize, ...)
  // and via environment variable LDR_CNTRL (DATAPSIZE, STACKPSIZE, ...).
  //
  // For shared memory, page size can be set dynamically via
  // shmctl(). Different shared memory regions can have different page
  // sizes.
  //
  // More information can be found at AIBM info center:
  //   http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp?topic=/com.ibm.aix.prftungd/doc/prftungd/multiple_page_size_app_support.htm
  //
  static struct {
    size_t pagesize;            // sysconf _SC_PAGESIZE (4K)
    size_t datapsize;           // default data page size (LDR_CNTRL DATAPSIZE)
    size_t shmpsize;            // default shared memory page size (LDR_CNTRL SHMPSIZE)
    size_t pthr_stack_pagesize; // stack page size of pthread threads
    size_t textpsize;           // default text page size (LDR_CNTRL STACKPSIZE)
    bool can_use_64K_pages;     // True if we can alloc 64K pages dynamically with Sys V shm.
    bool can_use_16M_pages;     // True if we can alloc 16M pages dynamically with Sys V shm.
    int error;                  // Error describing if something went wrong at multipage init.
  } g_multipage_support = {
    (size_t) -1,
    (size_t) -1,
    (size_t) -1,
    (size_t) -1,
    (size_t) -1,
    false, false,
    0
  };
  
  // We must not accidentally allocate memory close to the BRK - even if
  // that would work - because then we prevent the BRK segment from
  // growing which may result in a malloc OOM even though there is
  // enough memory. The problem only arises if we shmat() or mmap() at
  // a specific wish address, e.g. to place the heap in a
  // compressed-oops-friendly way.
  static bool is_close_to_brk(address a) {
    assert0(g_brk_at_startup != NULL);
    if (a >= g_brk_at_startup &&
        a < (g_brk_at_startup + MaxExpectedDataSegmentSize)) {
      return true;
    }
    return false;
  }
  
  julong os::available_memory() {
    return Aix::available_memory();
  }
  
  julong os::Aix::available_memory() {
    // Avoid expensive API call here, as returned value will always be null.
    if (os::Aix::on_pase()) {
      return 0x0LL;
    }
    os::Aix::meminfo_t mi;
    if (os::Aix::get_meminfo(&mi)) {
      return mi.real_free;
    } else {
      return ULONG_MAX;
    }
  }
  
  julong os::physical_memory() {
    return Aix::physical_memory();
  }
  
  // Return true if user is running as root.
  
  bool os::have_special_privileges() {
    static bool init = false;
    static bool privileges = false;
    if (!init) {
      privileges = (getuid() != geteuid()) || (getgid() != getegid());
      init = true;
    }
    return privileges;
  }
  
  // Helper function, emulates disclaim64 using multiple 32bit disclaims
  // because we cannot use disclaim64() on AS/400 and old AIX releases.
  static bool my_disclaim64(char* addr, size_t size) {
  
    if (size == 0) {
      return true;
    }
  
    // Maximum size 32bit disclaim() accepts. (Theoretically 4GB, but I just do not trust that.)
    const unsigned int maxDisclaimSize = 0x40000000;
  
    const unsigned int numFullDisclaimsNeeded = (size / maxDisclaimSize);
    const unsigned int lastDisclaimSize = (size % maxDisclaimSize);
  
    char* p = addr;
  
    for (int i = 0; i < numFullDisclaimsNeeded; i ++) {
      if (::disclaim(p, maxDisclaimSize, DISCLAIM_ZEROMEM) != 0) {
        trcVerbose("Cannot disclaim %p - %p (errno %d)\n", p, p + maxDisclaimSize, errno);
        return false;
      }
      p += maxDisclaimSize;
    }
  
    if (lastDisclaimSize > 0) {
      if (::disclaim(p, lastDisclaimSize, DISCLAIM_ZEROMEM) != 0) {
        trcVerbose("Cannot disclaim %p - %p (errno %d)\n", p, p + lastDisclaimSize, errno);
        return false;
      }
    }
  
    return true;
  }
  
  // Cpu architecture string
  #if defined(PPC32)
  static char cpu_arch[] = "ppc";
  #elif defined(PPC64)
  static char cpu_arch[] = "ppc64";
  #else
  #error Add appropriate cpu_arch setting
  #endif
  
  // Wrap the function "vmgetinfo" which is not available on older OS releases.
  static int checked_vmgetinfo(void *out, int command, int arg) {
    if (os::Aix::on_pase() && os::Aix::os_version_short() < 0x0601) {
      guarantee(false, "cannot call vmgetinfo on AS/400 older than V6R1");
    }
    return ::vmgetinfo(out, command, arg);
  }
  
  // Given an address, returns the size of the page backing that address.
  size_t os::Aix::query_pagesize(void* addr) {
  
    if (os::Aix::on_pase() && os::Aix::os_version_short() < 0x0601) {
      // AS/400 older than V6R1: no vmgetinfo here, default to 4K
      return 4*K;
    }
  
    vm_page_info pi;
    pi.addr = (uint64_t)addr;
    if (checked_vmgetinfo(&pi, VM_PAGE_INFO, sizeof(pi)) == 0) {
      return pi.pagesize;
    } else {
      assert(false, "vmgetinfo failed to retrieve page size");
      return 4*K;
    }
  }
  
  void os::Aix::initialize_system_info() {
  
    // Get the number of online(logical) cpus instead of configured.
    os::_processor_count = sysconf(_SC_NPROCESSORS_ONLN);
    assert(_processor_count > 0, "_processor_count must be > 0");
  
    // Retrieve total physical storage.
    os::Aix::meminfo_t mi;
    if (!os::Aix::get_meminfo(&mi)) {
      assert(false, "os::Aix::get_meminfo failed.");
    }
    _physical_memory = (julong) mi.real_total;
  }
  
  // Helper function for tracing page sizes.
  static const char* describe_pagesize(size_t pagesize) {
    switch (pagesize) {
      case 4*K : return "4K";
      case 64*K: return "64K";
      case 16*M: return "16M";
      case 16*G: return "16G";
      default:
        assert(false, "surprise");
        return "??";
    }
  }
  
  // Probe OS for multipage support.
  // Will fill the global g_multipage_support structure.
  // Must be called before calling os::large_page_init().
  static void query_multipage_support() {
  
    guarantee(g_multipage_support.pagesize == -1,
              "do not call twice");
  
    g_multipage_support.pagesize = ::sysconf(_SC_PAGESIZE);
  
    // This really would surprise me.
    assert(g_multipage_support.pagesize == 4*K, "surprise!");
  
    // Query default data page size (default page size for C-Heap, pthread stacks and .bss).
    // Default data page size is defined either by linker options (-bdatapsize)
    // or by environment variable LDR_CNTRL (suboption DATAPSIZE). If none is given,
    // default should be 4K.
    {
      void* p = ::malloc(16*M);
      g_multipage_support.datapsize = os::Aix::query_pagesize(p);
      ::free(p);
    }
  
    // Query default shm page size (LDR_CNTRL SHMPSIZE).
    // Note that this is pure curiosity. We do not rely on default page size but set
    // our own page size after allocated.
    {
      const int shmid = ::shmget(IPC_PRIVATE, 1, IPC_CREAT | S_IRUSR | S_IWUSR);
      guarantee(shmid != -1, "shmget failed");
      void* p = ::shmat(shmid, NULL, 0);
      ::shmctl(shmid, IPC_RMID, NULL);
      guarantee(p != (void*) -1, "shmat failed");
      g_multipage_support.shmpsize = os::Aix::query_pagesize(p);
      ::shmdt(p);
    }
  
    // Before querying the stack page size, make sure we are not running as primordial
    // thread (because primordial thread's stack may have different page size than
    // pthread thread stacks). Running a VM on the primordial thread won't work for a
    // number of reasons so we may just as well guarantee it here.
    guarantee0(!os::is_primordial_thread());
  
    // Query pthread stack page size. Should be the same as data page size because
    // pthread stacks are allocated from C-Heap.
    {
      int dummy = 0;
      g_multipage_support.pthr_stack_pagesize = os::Aix::query_pagesize(&dummy);
    }
  
    // Query default text page size (LDR_CNTRL TEXTPSIZE).
    {
      address any_function =
        resolve_function_descriptor_to_code_pointer((address)describe_pagesize);
      g_multipage_support.textpsize = os::Aix::query_pagesize(any_function);
    }
  
    // Now probe for support of 64K pages and 16M pages.
  
    // Before OS/400 V6R1, there is no support for pages other than 4K.
    if (os::Aix::on_pase_V5R4_or_older()) {
      trcVerbose("OS/400 < V6R1 - no large page support.");
      g_multipage_support.error = ERROR_MP_OS_TOO_OLD;
      goto query_multipage_support_end;
    }
  
    // Now check which page sizes the OS claims it supports, and of those, which actually can be used.
    {
      const int MAX_PAGE_SIZES = 4;
      psize_t sizes[MAX_PAGE_SIZES];
      const int num_psizes = checked_vmgetinfo(sizes, VMINFO_GETPSIZES, MAX_PAGE_SIZES);
      if (num_psizes == -1) {
        trcVerbose("vmgetinfo(VMINFO_GETPSIZES) failed (errno: %d)", errno);
        trcVerbose("disabling multipage support.");
        g_multipage_support.error = ERROR_MP_VMGETINFO_FAILED;
        goto query_multipage_support_end;
      }
      guarantee(num_psizes > 0, "vmgetinfo(.., VMINFO_GETPSIZES, ...) failed.");
      assert(num_psizes <= MAX_PAGE_SIZES, "Surprise! more than 4 page sizes?");
      trcVerbose("vmgetinfo(.., VMINFO_GETPSIZES, ...) returns %d supported page sizes: ", num_psizes);
      for (int i = 0; i < num_psizes; i ++) {
        trcVerbose(" %s ", describe_pagesize(sizes[i]));
      }
  
      // Can we use 64K, 16M pages?
      for (int i = 0; i < num_psizes; i ++) {
        const size_t pagesize = sizes[i];
        if (pagesize != 64*K && pagesize != 16*M) {
          continue;
        }
        bool can_use = false;
        trcVerbose("Probing support for %s pages...", describe_pagesize(pagesize));
        const int shmid = ::shmget(IPC_PRIVATE, pagesize,
          IPC_CREAT | S_IRUSR | S_IWUSR);
        guarantee0(shmid != -1); // Should always work.
        // Try to set pagesize.
        struct shmid_ds shm_buf = { 0 };
        shm_buf.shm_pagesize = pagesize;
        if (::shmctl(shmid, SHM_PAGESIZE, &shm_buf) != 0) {
          const int en = errno;
          ::shmctl(shmid, IPC_RMID, NULL); // As early as possible!
          trcVerbose("shmctl(SHM_PAGESIZE) failed with errno=%d", errno);
        } else {
          // Attach and double check pageisze.
          void* p = ::shmat(shmid, NULL, 0);
          ::shmctl(shmid, IPC_RMID, NULL); // As early as possible!
          guarantee0(p != (void*) -1); // Should always work.
          const size_t real_pagesize = os::Aix::query_pagesize(p);
          if (real_pagesize != pagesize) {
            trcVerbose("real page size (" SIZE_FORMAT_HEX ") differs.", real_pagesize);
          } else {
            can_use = true;
          }
          ::shmdt(p);
        }
        trcVerbose("Can use: %s", (can_use ? "yes" : "no"));
        if (pagesize == 64*K) {
          g_multipage_support.can_use_64K_pages = can_use;
        } else if (pagesize == 16*M) {
          g_multipage_support.can_use_16M_pages = can_use;
        }
      }
  
    } // end: check which pages can be used for shared memory
  
  query_multipage_support_end:
  
    trcVerbose("base page size (sysconf _SC_PAGESIZE): %s",
        describe_pagesize(g_multipage_support.pagesize));
    trcVerbose("Data page size (C-Heap, bss, etc): %s",
        describe_pagesize(g_multipage_support.datapsize));
    trcVerbose("Text page size: %s",
        describe_pagesize(g_multipage_support.textpsize));
    trcVerbose("Thread stack page size (pthread): %s",
        describe_pagesize(g_multipage_support.pthr_stack_pagesize));
    trcVerbose("Default shared memory page size: %s",
        describe_pagesize(g_multipage_support.shmpsize));
    trcVerbose("Can use 64K pages dynamically with shared memory: %s",
        (g_multipage_support.can_use_64K_pages ? "yes" :"no"));
    trcVerbose("Can use 16M pages dynamically with shared memory: %s",
        (g_multipage_support.can_use_16M_pages ? "yes" :"no"));
    trcVerbose("Multipage error details: %d",
        g_multipage_support.error);
  
    // sanity checks
    assert0(g_multipage_support.pagesize == 4*K);
    assert0(g_multipage_support.datapsize == 4*K || g_multipage_support.datapsize == 64*K);
    assert0(g_multipage_support.textpsize == 4*K || g_multipage_support.textpsize == 64*K);
    assert0(g_multipage_support.pthr_stack_pagesize == g_multipage_support.datapsize);
    assert0(g_multipage_support.shmpsize == 4*K || g_multipage_support.shmpsize == 64*K);
  
  }
  
  void os::init_system_properties_values() {
  
  #ifndef OVERRIDE_LIBPATH
    #define DEFAULT_LIBPATH "/lib:/usr/lib"
  #else
    #define DEFAULT_LIBPATH OVERRIDE_LIBPATH
  #endif
  #define EXTENSIONS_DIR  "/lib/ext"
  
    // Buffer that fits several sprintfs.
    // Note that the space for the trailing null is provided
    // by the nulls included by the sizeof operator.
    const size_t bufsize =
      MAX2((size_t)MAXPATHLEN,  // For dll_dir & friends.
           (size_t)MAXPATHLEN + sizeof(EXTENSIONS_DIR)); // extensions dir
    char *buf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
  
    // sysclasspath, java_home, dll_dir
    {
      char *pslash;
      os::jvm_path(buf, bufsize);
  
      // Found the full path to libjvm.so.
      // Now cut the path to <java_home>/jre if we can.
      pslash = strrchr(buf, '/');
      if (pslash != NULL) {
        *pslash = '\0';            // Get rid of /libjvm.so.
      }
      pslash = strrchr(buf, '/');
      if (pslash != NULL) {
        *pslash = '\0';            // Get rid of /{client|server|hotspot}.
      }
      Arguments::set_dll_dir(buf);
  
      if (pslash != NULL) {
        pslash = strrchr(buf, '/');
        if (pslash != NULL) {
          *pslash = '\0';        // Get rid of /lib.
        }
      }
      Arguments::set_java_home(buf);
      if (!set_boot_path('/', ':')) {
        vm_exit_during_initialization("Failed setting boot class path.", NULL);
      }
    }
  
    // Where to look for native libraries.
  
    // On Aix we get the user setting of LIBPATH.
    // Eventually, all the library path setting will be done here.
    // Get the user setting of LIBPATH.
    const char *v = ::getenv("LIBPATH");
    const char *v_colon = ":";
    if (v == NULL) { v = ""; v_colon = ""; }
  
    // Concatenate user and invariant part of ld_library_path.
    // That's +1 for the colon and +1 for the trailing '\0'.
    char *ld_library_path = NEW_C_HEAP_ARRAY(char, strlen(v) + 1 + sizeof(DEFAULT_LIBPATH) + 1, mtInternal);
    sprintf(ld_library_path, "%s%s" DEFAULT_LIBPATH, v, v_colon);
    Arguments::set_library_path(ld_library_path);
    FREE_C_HEAP_ARRAY(char, ld_library_path);
  
    // Extensions directories.
    sprintf(buf, "%s" EXTENSIONS_DIR, Arguments::get_java_home());
    Arguments::set_ext_dirs(buf);
  
    FREE_C_HEAP_ARRAY(char, buf);
  
  #undef DEFAULT_LIBPATH
  #undef EXTENSIONS_DIR
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  // breakpoint support
  
  void os::breakpoint() {
    BREAKPOINT;
  }
  
  extern "C" void breakpoint() {
    // use debugger to set breakpoint here
  }
  
  // retrieve memory information.
  // Returns false if something went wrong;
  // content of pmi undefined in this case.
  bool os::Aix::get_meminfo(meminfo_t* pmi) {
  
    assert(pmi, "get_meminfo: invalid parameter");
  
    memset(pmi, 0, sizeof(meminfo_t));
  
    if (os::Aix::on_pase()) {
      // On PASE, use the libo4 porting library.
  
      unsigned long long virt_total = 0;
      unsigned long long real_total = 0;
      unsigned long long real_free = 0;
      unsigned long long pgsp_total = 0;
      unsigned long long pgsp_free = 0;
      if (libo4::get_memory_info(&virt_total, &real_total, &real_free, &pgsp_total, &pgsp_free)) {
        pmi->virt_total = virt_total;
        pmi->real_total = real_total;
        pmi->real_free = real_free;
        pmi->pgsp_total = pgsp_total;
        pmi->pgsp_free = pgsp_free;
        return true;
      }
      return false;
  
    } else {
  
      // On AIX, I use the (dynamically loaded) perfstat library to retrieve memory statistics
      // See:
      // http://publib.boulder.ibm.com/infocenter/systems/index.jsp
      //        ?topic=/com.ibm.aix.basetechref/doc/basetrf1/perfstat_memtot.htm
      // http://publib.boulder.ibm.com/infocenter/systems/index.jsp
      //        ?topic=/com.ibm.aix.files/doc/aixfiles/libperfstat.h.htm
  
      perfstat_memory_total_t psmt;
      memset (&psmt, '\0', sizeof(psmt));
      const int rc = libperfstat::perfstat_memory_total(NULL, &psmt, sizeof(psmt), 1);
      if (rc == -1) {
        trcVerbose("perfstat_memory_total() failed (errno=%d)", errno);
        assert(0, "perfstat_memory_total() failed");
        return false;
      }
  
      assert(rc == 1, "perfstat_memory_total() - weird return code");
  
      // excerpt from
      // http://publib.boulder.ibm.com/infocenter/systems/index.jsp
      //        ?topic=/com.ibm.aix.files/doc/aixfiles/libperfstat.h.htm
      // The fields of perfstat_memory_total_t:
      // u_longlong_t virt_total         Total virtual memory (in 4 KB pages).
      // u_longlong_t real_total         Total real memory (in 4 KB pages).
      // u_longlong_t real_free          Free real memory (in 4 KB pages).
      // u_longlong_t pgsp_total         Total paging space (in 4 KB pages).
      // u_longlong_t pgsp_free          Free paging space (in 4 KB pages).
  
      pmi->virt_total = psmt.virt_total * 4096;
      pmi->real_total = psmt.real_total * 4096;
      pmi->real_free = psmt.real_free * 4096;
      pmi->pgsp_total = psmt.pgsp_total * 4096;
      pmi->pgsp_free = psmt.pgsp_free * 4096;
  
      return true;
  
    }
  } // end os::Aix::get_meminfo
  
  //////////////////////////////////////////////////////////////////////////////
  // create new thread
  
  // Thread start routine for all newly created threads
  static void *thread_native_entry(Thread *thread) {
  
    thread->record_stack_base_and_size();
  
    const pthread_t pthread_id = ::pthread_self();
    const tid_t kernel_thread_id = ::thread_self();
  
    LogTarget(Info, os, thread) lt;
    if (lt.is_enabled()) {
      address low_address = thread->stack_end();
      address high_address = thread->stack_base();
      lt.print("Thread is alive (tid: " UINTX_FORMAT ", kernel thread id: " UINTX_FORMAT
               ", stack [" PTR_FORMAT " - " PTR_FORMAT " (" SIZE_FORMAT "k using %uk pages)).",
               os::current_thread_id(), (uintx) kernel_thread_id, low_address, high_address,
               (high_address - low_address) / K, os::Aix::query_pagesize(low_address) / K);
    }
  
    // Normally, pthread stacks on AIX live in the data segment (are allocated with malloc()
    // by the pthread library). In rare cases, this may not be the case, e.g. when third-party
    // tools hook pthread_create(). In this case, we may run into problems establishing
    // guard pages on those stacks, because the stacks may reside in memory which is not
    // protectable (shmated).
    if (thread->stack_base() > ::sbrk(0)) {
      log_warning(os, thread)("Thread stack not in data segment.");
    }
  
    // Try to randomize the cache line index of hot stack frames.
    // This helps when threads of the same stack traces evict each other's
    // cache lines. The threads can be either from the same JVM instance, or
    // from different JVM instances. The benefit is especially true for
    // processors with hyperthreading technology.
  
    static int counter = 0;
    int pid = os::current_process_id();
    alloca(((pid ^ counter++) & 7) * 128);
  
    thread->initialize_thread_current();
  
    OSThread* osthread = thread->osthread();
  
    // Thread_id is pthread id.
    osthread->set_thread_id(pthread_id);
  
    // .. but keep kernel thread id too for diagnostics
    osthread->set_kernel_thread_id(kernel_thread_id);
  
    // Initialize signal mask for this thread.
    PosixSignals::hotspot_sigmask(thread);
  
    // Initialize floating point control register.
    os::Aix::init_thread_fpu_state();
  
    assert(osthread->get_state() == RUNNABLE, "invalid os thread state");
  
    // Call one more level start routine.
    thread->call_run();
  
    // Note: at this point the thread object may already have deleted itself.
    // Prevent dereferencing it from here on out.
    thread = NULL;
  
    log_info(os, thread)("Thread finished (tid: " UINTX_FORMAT ", kernel thread id: " UINTX_FORMAT ").",
      os::current_thread_id(), (uintx) kernel_thread_id);
  
    return 0;
  }
  
  bool os::create_thread(Thread* thread, ThreadType thr_type,
                         size_t req_stack_size) {
  
    assert(thread->osthread() == NULL, "caller responsible");
  
    // Allocate the OSThread object.
    OSThread* osthread = new OSThread(NULL, NULL);
    if (osthread == NULL) {
      return false;
    }
  
    // Set the correct thread state.
    osthread->set_thread_type(thr_type);
  
    // Initial state is ALLOCATED but not INITIALIZED
    osthread->set_state(ALLOCATED);
  
    thread->set_osthread(osthread);
  
    // Init thread attributes.
    pthread_attr_t attr;
    pthread_attr_init(&attr);
    guarantee(pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED) == 0, "???");
  
    // Make sure we run in 1:1 kernel-user-thread mode.
    if (os::Aix::on_aix()) {
      guarantee(pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM) == 0, "???");
      guarantee(pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED) == 0, "???");
    }
  
    // Start in suspended state, and in os::thread_start, wake the thread up.
    guarantee(pthread_attr_setsuspendstate_np(&attr, PTHREAD_CREATE_SUSPENDED_NP) == 0, "???");
  
    // Calculate stack size if it's not specified by caller.
    size_t stack_size = os::Posix::get_initial_stack_size(thr_type, req_stack_size);
  
    // JDK-8187028: It was observed that on some configurations (4K backed thread stacks)
    // the real thread stack size may be smaller than the requested stack size, by as much as 64K.
    // This very much looks like a pthread lib error. As a workaround, increase the stack size
    // by 64K for small thread stacks (arbitrarily choosen to be < 4MB)
    if (stack_size < 4096 * K) {
      stack_size += 64 * K;
    }
  
    // On Aix, pthread_attr_setstacksize fails with huge values and leaves the
    // thread size in attr unchanged. If this is the minimal stack size as set
    // by pthread_attr_init this leads to crashes after thread creation. E.g. the
    // guard pages might not fit on the tiny stack created.
    int ret = pthread_attr_setstacksize(&attr, stack_size);
    if (ret != 0) {
      log_warning(os, thread)("The %sthread stack size specified is invalid: " SIZE_FORMAT "k",
                              (thr_type == compiler_thread) ? "compiler " : ((thr_type == java_thread) ? "" : "VM "),
                              stack_size / K);
      thread->set_osthread(NULL);
      delete osthread;
      return false;
    }
  
    // Save some cycles and a page by disabling OS guard pages where we have our own
    // VM guard pages (in java threads). For other threads, keep system default guard
    // pages in place.
    if (thr_type == java_thread || thr_type == compiler_thread) {
      ret = pthread_attr_setguardsize(&attr, 0);
    }
  
    ResourceMark rm;
    pthread_t tid = 0;
  
    if (ret == 0) {
      int limit = 3;
      do {
        ret = pthread_create(&tid, &attr, (void* (*)(void*)) thread_native_entry, thread);
      } while (ret == EAGAIN && limit-- > 0);
    }
  
    if (ret == 0) {
      char buf[64];
      log_info(os, thread)("Thread \"%s\" started (pthread id: " UINTX_FORMAT ", attributes: %s). ",
                           thread->name(), (uintx) tid, os::Posix::describe_pthread_attr(buf, sizeof(buf), &attr));
    } else {
      char buf[64];
      log_warning(os, thread)("Failed to start thread \"%s\" - pthread_create failed (%d=%s) for attributes: %s.",
                              thread->name(), ret, os::errno_name(ret), os::Posix::describe_pthread_attr(buf, sizeof(buf), &attr));
      // Log some OS information which might explain why creating the thread failed.
      log_info(os, thread)("Number of threads approx. running in the VM: %d", Threads::number_of_threads());
      LogStream st(Log(os, thread)::info());
      os::Posix::print_rlimit_info(&st);
      os::print_memory_info(&st);
    }
  
    pthread_attr_destroy(&attr);
  
    if (ret != 0) {
      // Need to clean up stuff we've allocated so far.
      thread->set_osthread(NULL);
      delete osthread;
      return false;
    }
  
    // OSThread::thread_id is the pthread id.
    osthread->set_thread_id(tid);
  
    return true;
  }
  
  /////////////////////////////////////////////////////////////////////////////
  // attach existing thread
  
  // bootstrap the main thread
  bool os::create_main_thread(JavaThread* thread) {
    assert(os::Aix::_main_thread == pthread_self(), "should be called inside main thread");
    return create_attached_thread(thread);
  }
  
  bool os::create_attached_thread(JavaThread* thread) {
  #ifdef ASSERT
      thread->verify_not_published();
  #endif
  
    // Allocate the OSThread object
    OSThread* osthread = new OSThread(NULL, NULL);
  
    if (osthread == NULL) {
      return false;
    }
  
    const pthread_t pthread_id = ::pthread_self();
    const tid_t kernel_thread_id = ::thread_self();
  
    // OSThread::thread_id is the pthread id.
    osthread->set_thread_id(pthread_id);
  
    // .. but keep kernel thread id too for diagnostics
    osthread->set_kernel_thread_id(kernel_thread_id);
  
    // initialize floating point control register
    os::Aix::init_thread_fpu_state();
  
    // Initial thread state is RUNNABLE
    osthread->set_state(RUNNABLE);
  
    thread->set_osthread(osthread);
  
    if (UseNUMA) {
      int lgrp_id = os::numa_get_group_id();
      if (lgrp_id != -1) {
        thread->set_lgrp_id(lgrp_id);
      }
    }
  
    // initialize signal mask for this thread
    // and save the caller's signal mask
    PosixSignals::hotspot_sigmask(thread);
  
    log_info(os, thread)("Thread attached (tid: " UINTX_FORMAT ", kernel thread id: " UINTX_FORMAT ").",
      os::current_thread_id(), (uintx) kernel_thread_id);
  
    return true;
  }
  
  void os::pd_start_thread(Thread* thread) {
    int status = pthread_continue_np(thread->osthread()->pthread_id());
    assert(status == 0, "thr_continue failed");
  }
  
  // Free OS resources related to the OSThread
  void os::free_thread(OSThread* osthread) {
    assert(osthread != NULL, "osthread not set");
  
    // We are told to free resources of the argument thread,
    // but we can only really operate on the current thread.
    assert(Thread::current()->osthread() == osthread,
           "os::free_thread but not current thread");
  
    // Restore caller's signal mask
    sigset_t sigmask = osthread->caller_sigmask();
    pthread_sigmask(SIG_SETMASK, &sigmask, NULL);
  
    delete osthread;
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  // time support
  
  // Time since start-up in seconds to a fine granularity.
  double os::elapsedTime() {
    return ((double)os::elapsed_counter()) / os::elapsed_frequency(); // nanosecond resolution
  }
  
  jlong os::elapsed_counter() {
    return javaTimeNanos() - initial_time_count;
  }
  
  jlong os::elapsed_frequency() {
    return NANOSECS_PER_SEC; // nanosecond resolution
  }
  
  bool os::supports_vtime() { return true; }
  
  double os::elapsedVTime() {
    struct rusage usage;
    int retval = getrusage(RUSAGE_THREAD, &usage);
    if (retval == 0) {
      return usage.ru_utime.tv_sec + usage.ru_stime.tv_sec + (usage.ru_utime.tv_usec + usage.ru_stime.tv_usec) / (1000.0 * 1000);
    } else {
      // better than nothing, but not much
      return elapsedTime();
    }
  }
  
  // We use mread_real_time here.
  // On AIX: If the CPU has a time register, the result will be RTC_POWER and
  // it has to be converted to real time. AIX documentations suggests to do
  // this unconditionally, so we do it.
  //
  // See: https://www.ibm.com/support/knowledgecenter/ssw_aix_61/com.ibm.aix.basetrf2/read_real_time.htm
  //
  // On PASE: mread_real_time will always return RTC_POWER_PC data, so no
  // conversion is necessary. However, mread_real_time will not return
  // monotonic results but merely matches read_real_time. So we need a tweak
  // to ensure monotonic results.
  //
  // For PASE no public documentation exists, just word by IBM
  jlong os::javaTimeNanos() {
    timebasestruct_t time;
    int rc = mread_real_time(&time, TIMEBASE_SZ);
    if (os::Aix::on_pase()) {
      assert(rc == RTC_POWER, "expected time format RTC_POWER from mread_real_time in PASE");
      jlong now = jlong(time.tb_high) * NANOSECS_PER_SEC + jlong(time.tb_low);
      jlong prev = max_real_time;
      if (now <= prev) {
        return prev;   // same or retrograde time;
      }
      jlong obsv = Atomic::cmpxchg(&max_real_time, prev, now);
      assert(obsv >= prev, "invariant");   // Monotonicity
      // If the CAS succeeded then we're done and return "now".
      // If the CAS failed and the observed value "obsv" is >= now then
      // we should return "obsv".  If the CAS failed and now > obsv > prv then
      // some other thread raced this thread and installed a new value, in which case
      // we could either (a) retry the entire operation, (b) retry trying to install now
      // or (c) just return obsv.  We use (c).   No loop is required although in some cases
      // we might discard a higher "now" value in deference to a slightly lower but freshly
      // installed obsv value.   That's entirely benign -- it admits no new orderings compared
      // to (a) or (b) -- and greatly reduces coherence traffic.
      // We might also condition (c) on the magnitude of the delta between obsv and now.
      // Avoiding excessive CAS operations to hot RW locations is critical.
      // See https://blogs.oracle.com/dave/entry/cas_and_cache_trivia_invalidate
      return (prev == obsv) ? now : obsv;
    } else {
      if (rc != RTC_POWER) {
        rc = time_base_to_time(&time, TIMEBASE_SZ);
        assert(rc != -1, "error calling time_base_to_time()");
      }
      return jlong(time.tb_high) * NANOSECS_PER_SEC + jlong(time.tb_low);
    }
  }
  
  void os::javaTimeNanos_info(jvmtiTimerInfo *info_ptr) {
    info_ptr->max_value = ALL_64_BITS;
    // mread_real_time() is monotonic (see 'os::javaTimeNanos()')
    info_ptr->may_skip_backward = false;
    info_ptr->may_skip_forward = false;
    info_ptr->kind = JVMTI_TIMER_ELAPSED;    // elapsed not CPU time
  }
  
  // Return the real, user, and system times in seconds from an
  // arbitrary fixed point in the past.
  bool os::getTimesSecs(double* process_real_time,
                        double* process_user_time,
                        double* process_system_time) {
    struct tms ticks;
    clock_t real_ticks = times(&ticks);
  
    if (real_ticks == (clock_t) (-1)) {
      return false;
    } else {
      double ticks_per_second = (double) clock_tics_per_sec;
      *process_user_time = ((double) ticks.tms_utime) / ticks_per_second;
      *process_system_time = ((double) ticks.tms_stime) / ticks_per_second;
      *process_real_time = ((double) real_ticks) / ticks_per_second;
  
      return true;
    }
  }
  
  char * os::local_time_string(char *buf, size_t buflen) {
    struct tm t;
    time_t long_time;
    time(&long_time);
    localtime_r(&long_time, &t);
    jio_snprintf(buf, buflen, "%d-%02d-%02d %02d:%02d:%02d",
                 t.tm_year + 1900, t.tm_mon + 1, t.tm_mday,
                 t.tm_hour, t.tm_min, t.tm_sec);
    return buf;
  }
  
  struct tm* os::localtime_pd(const time_t* clock, struct tm* res) {
    return localtime_r(clock, res);
  }
  
  intx os::current_thread_id() {
    return (intx)pthread_self();
  }
  
  int os::current_process_id() {
    return getpid();
  }
  
  // DLL functions
  
  const char* os::dll_file_extension() { return ".so"; }
  
  // This must be hard coded because it's the system's temporary
  // directory not the java application's temp directory, ala java.io.tmpdir.
  const char* os::get_temp_directory() { return "/tmp"; }
  
  // Check if addr is inside libjvm.so.
  bool os::address_is_in_vm(address addr) {
  
    // Input could be a real pc or a function pointer literal. The latter
    // would be a function descriptor residing in the data segment of a module.
    loaded_module_t lm;
    if (LoadedLibraries::find_for_text_address(addr, &lm) != NULL) {
      return lm.is_in_vm;
    } else if (LoadedLibraries::find_for_data_address(addr, &lm) != NULL) {
      return lm.is_in_vm;
    } else {
      return false;
    }
  
  }
  
  // Resolve an AIX function descriptor literal to a code pointer.
  // If the input is a valid code pointer to a text segment of a loaded module,
  //   it is returned unchanged.
  // If the input is a valid AIX function descriptor, it is resolved to the
  //   code entry point.
  // If the input is neither a valid function descriptor nor a valid code pointer,
  //   NULL is returned.
  static address resolve_function_descriptor_to_code_pointer(address p) {
  
    if (LoadedLibraries::find_for_text_address(p, NULL) != NULL) {
      // It is a real code pointer.
      return p;
    } else if (LoadedLibraries::find_for_data_address(p, NULL) != NULL) {
      // Pointer to data segment, potential function descriptor.
      address code_entry = (address)(((FunctionDescriptor*)p)->entry());
      if (LoadedLibraries::find_for_text_address(code_entry, NULL) != NULL) {
        // It is a function descriptor.
        return code_entry;
      }
    }
  
    return NULL;
  }
  
  bool os::dll_address_to_function_name(address addr, char *buf,
                                        int buflen, int *offset,
                                        bool demangle) {
    if (offset) {
      *offset = -1;
    }
    // Buf is not optional, but offset is optional.
    assert(buf != NULL, "sanity check");
    buf[0] = '\0';
  
    // Resolve function ptr literals first.
    addr = resolve_function_descriptor_to_code_pointer(addr);
    if (!addr) {
      return false;
    }
  
    return AixSymbols::get_function_name(addr, buf, buflen, offset, NULL, demangle);
  }
  
  bool os::dll_address_to_library_name(address addr, char* buf,
                                       int buflen, int* offset) {
    if (offset) {
      *offset = -1;
    }
    // Buf is not optional, but offset is optional.
    assert(buf != NULL, "sanity check");
    buf[0] = '\0';
  
    // Resolve function ptr literals first.
    addr = resolve_function_descriptor_to_code_pointer(addr);
    if (!addr) {
      return false;
    }
  
    return AixSymbols::get_module_name(addr, buf, buflen);
  }
  
  // Loads .dll/.so and in case of error it checks if .dll/.so was built
  // for the same architecture as Hotspot is running on.
  void *os::dll_load(const char *filename, char *ebuf, int ebuflen) {
  
    log_info(os)("attempting shared library load of %s", filename);
  
    if (ebuf && ebuflen > 0) {
      ebuf[0] = '\0';
      ebuf[ebuflen - 1] = '\0';
    }
  
    if (!filename || strlen(filename) == 0) {
      ::strncpy(ebuf, "dll_load: empty filename specified", ebuflen - 1);
      return NULL;
    }
  
    // RTLD_LAZY is currently not implemented. The dl is loaded immediately with all its dependants.
    void * result= ::dlopen(filename, RTLD_LAZY);
    if (result != NULL) {
      Events::log(NULL, "Loaded shared library %s", filename);
      // Reload dll cache. Don't do this in signal handling.
      LoadedLibraries::reload();
      log_info(os)("shared library load of %s was successful", filename);
      return result;
    } else {
      // error analysis when dlopen fails
      const char* error_report = ::dlerror();
      if (error_report == NULL) {
        error_report = "dlerror returned no error description";
      }
      if (ebuf != NULL && ebuflen > 0) {
        snprintf(ebuf, ebuflen - 1, "%s, LIBPATH=%s, LD_LIBRARY_PATH=%s : %s",
                 filename, ::getenv("LIBPATH"), ::getenv("LD_LIBRARY_PATH"), error_report);
      }
      Events::log(NULL, "Loading shared library %s failed, %s", filename, error_report);
      log_info(os)("shared library load of %s failed, %s", filename, error_report);
    }
    return NULL;
  }
  
  void* os::dll_lookup(void* handle, const char* name) {
    void* res = dlsym(handle, name);
    return res;
  }
  
  void* os::get_default_process_handle() {
    return (void*)::dlopen(NULL, RTLD_LAZY);
  }
  
  void os::print_dll_info(outputStream *st) {
    st->print_cr("Dynamic libraries:");
    LoadedLibraries::print(st);
  }
  
  void os::get_summary_os_info(char* buf, size_t buflen) {
    // There might be something more readable than uname results for AIX.
    struct utsname name;
    uname(&name);
    snprintf(buf, buflen, "%s %s", name.release, name.version);
  }
  
  int os::get_loaded_modules_info(os::LoadedModulesCallbackFunc callback, void *param) {
    // Not yet implemented.
    return 0;
  }
  
  void os::print_os_info_brief(outputStream* st) {
    uint32_t ver = os::Aix::os_version();
    st->print_cr("AIX kernel version %u.%u.%u.%u",
                 (ver >> 24) & 0xFF, (ver >> 16) & 0xFF, (ver >> 8) & 0xFF, ver & 0xFF);
  
    os::Posix::print_uname_info(st);
  
    // Linux uses print_libversion_info(st); here.
  }
  
  void os::print_os_info(outputStream* st) {
    st->print_cr("OS:");
  
    os::Posix::print_uname_info(st);
  
    uint32_t ver = os::Aix::os_version();
    st->print_cr("AIX kernel version %u.%u.%u.%u",
                 (ver >> 24) & 0xFF, (ver >> 16) & 0xFF, (ver >> 8) & 0xFF, ver & 0xFF);
  
    os::Posix::print_uptime_info(st);
  
    os::Posix::print_rlimit_info(st);
  
    os::Posix::print_load_average(st);
  
    // _SC_THREAD_THREADS_MAX is the maximum number of threads within a process.
    long tmax = sysconf(_SC_THREAD_THREADS_MAX);
    st->print_cr("maximum #threads within a process:%ld", tmax);
  
    // print wpar info
    libperfstat::wparinfo_t wi;
    if (libperfstat::get_wparinfo(&wi)) {
      st->print_cr("wpar info");
      st->print_cr("name: %s", wi.name);
      st->print_cr("id:   %d", wi.wpar_id);
      st->print_cr("type: %s", (wi.app_wpar ? "application" : "system"));
    }
  
    VM_Version::print_platform_virtualization_info(st);
  }
  
  void os::print_memory_info(outputStream* st) {
  
    st->print_cr("Memory:");
  
    st->print_cr("  Base page size (sysconf _SC_PAGESIZE):  %s",
      describe_pagesize(g_multipage_support.pagesize));
    st->print_cr("  Data page size (C-Heap, bss, etc):      %s",
      describe_pagesize(g_multipage_support.datapsize));
    st->print_cr("  Text page size:                         %s",
      describe_pagesize(g_multipage_support.textpsize));
    st->print_cr("  Thread stack page size (pthread):       %s",
      describe_pagesize(g_multipage_support.pthr_stack_pagesize));
    st->print_cr("  Default shared memory page size:        %s",
      describe_pagesize(g_multipage_support.shmpsize));
    st->print_cr("  Can use 64K pages dynamically with shared memory:  %s",
      (g_multipage_support.can_use_64K_pages ? "yes" :"no"));
    st->print_cr("  Can use 16M pages dynamically with shared memory: %s",
      (g_multipage_support.can_use_16M_pages ? "yes" :"no"));
    st->print_cr("  Multipage error: %d",
      g_multipage_support.error);
    st->cr();
    st->print_cr("  os::vm_page_size:       %s", describe_pagesize(os::vm_page_size()));
  
    // print out LDR_CNTRL because it affects the default page sizes
    const char* const ldr_cntrl = ::getenv("LDR_CNTRL");
    st->print_cr("  LDR_CNTRL=%s.", ldr_cntrl ? ldr_cntrl : "<unset>");
  
    // Print out EXTSHM because it is an unsupported setting.
    const char* const extshm = ::getenv("EXTSHM");
    st->print_cr("  EXTSHM=%s.", extshm ? extshm : "<unset>");
    if ( (strcmp(extshm, "on") == 0) || (strcmp(extshm, "ON") == 0) ) {
      st->print_cr("  *** Unsupported! Please remove EXTSHM from your environment! ***");
    }
  
    // Print out AIXTHREAD_GUARDPAGES because it affects the size of pthread stacks.
    const char* const aixthread_guardpages = ::getenv("AIXTHREAD_GUARDPAGES");
    st->print_cr("  AIXTHREAD_GUARDPAGES=%s.",
        aixthread_guardpages ? aixthread_guardpages : "<unset>");
    st->cr();
  
    os::Aix::meminfo_t mi;
    if (os::Aix::get_meminfo(&mi)) {
      if (os::Aix::on_aix()) {
        st->print_cr("physical total : " SIZE_FORMAT, mi.real_total);
        st->print_cr("physical free  : " SIZE_FORMAT, mi.real_free);
        st->print_cr("swap total     : " SIZE_FORMAT, mi.pgsp_total);
        st->print_cr("swap free      : " SIZE_FORMAT, mi.pgsp_free);
      } else {
        // PASE - Numbers are result of QWCRSSTS; they mean:
        // real_total: Sum of all system pools
        // real_free: always 0
        // pgsp_total: we take the size of the system ASP
        // pgsp_free: size of system ASP times percentage of system ASP unused
        st->print_cr("physical total     : " SIZE_FORMAT, mi.real_total);
        st->print_cr("system asp total   : " SIZE_FORMAT, mi.pgsp_total);
        st->print_cr("%% system asp used : %.2f",
          mi.pgsp_total ? (100.0f * (mi.pgsp_total - mi.pgsp_free) / mi.pgsp_total) : -1.0f);
      }
    }
    st->cr();
  
    // Print program break.
    st->print_cr("Program break at VM startup: " PTR_FORMAT ".", p2i(g_brk_at_startup));
    address brk_now = (address)::sbrk(0);
    if (brk_now != (address)-1) {
      st->print_cr("Program break now          : " PTR_FORMAT " (distance: " SIZE_FORMAT "k).",
                   p2i(brk_now), (size_t)((brk_now - g_brk_at_startup) / K));
    }
    st->print_cr("MaxExpectedDataSegmentSize    : " SIZE_FORMAT "k.", MaxExpectedDataSegmentSize / K);
    st->cr();
  
    // Print segments allocated with os::reserve_memory.
    st->print_cr("internal virtual memory regions used by vm:");
    vmembk_print_on(st);
  }
  
  // Get a string for the cpuinfo that is a summary of the cpu type
  void os::get_summary_cpu_info(char* buf, size_t buflen) {
    // read _system_configuration.version
    switch (_system_configuration.version) {
    case PV_9:
      strncpy(buf, "Power PC 9", buflen);
      break;
    case PV_8:
      strncpy(buf, "Power PC 8", buflen);
      break;
    case PV_7:
      strncpy(buf, "Power PC 7", buflen);
      break;
    case PV_6_1:
      strncpy(buf, "Power PC 6 DD1.x", buflen);
      break;
    case PV_6:
      strncpy(buf, "Power PC 6", buflen);
      break;
    case PV_5:
      strncpy(buf, "Power PC 5", buflen);
      break;
    case PV_5_2:
      strncpy(buf, "Power PC 5_2", buflen);
      break;
    case PV_5_3:
      strncpy(buf, "Power PC 5_3", buflen);
      break;
    case PV_5_Compat:
      strncpy(buf, "PV_5_Compat", buflen);
      break;
    case PV_6_Compat:
      strncpy(buf, "PV_6_Compat", buflen);
      break;
    case PV_7_Compat:
      strncpy(buf, "PV_7_Compat", buflen);
      break;
    case PV_8_Compat:
      strncpy(buf, "PV_8_Compat", buflen);
      break;
    case PV_9_Compat:
      strncpy(buf, "PV_9_Compat", buflen);
      break;
    default:
      strncpy(buf, "unknown", buflen);
    }
  }
  
  void os::pd_print_cpu_info(outputStream* st, char* buf, size_t buflen) {
    // Nothing to do beyond of what os::print_cpu_info() does.
  }
  
  static char saved_jvm_path[MAXPATHLEN] = {0};
  
  // Find the full path to the current module, libjvm.so.
  void os::jvm_path(char *buf, jint buflen) {
    // Error checking.
    if (buflen < MAXPATHLEN) {
      assert(false, "must use a large-enough buffer");
      buf[0] = '\0';
      return;
    }
    // Lazy resolve the path to current module.
    if (saved_jvm_path[0] != 0) {
      strcpy(buf, saved_jvm_path);
      return;
    }
  
    Dl_info dlinfo;
    int ret = dladdr(CAST_FROM_FN_PTR(void *, os::jvm_path), &dlinfo);
    assert(ret != 0, "cannot locate libjvm");
    char* rp = os::Posix::realpath((char *)dlinfo.dli_fname, buf, buflen);
    assert(rp != NULL, "error in realpath(): maybe the 'path' argument is too long?");
  
    if (Arguments::sun_java_launcher_is_altjvm()) {
      // Support for the java launcher's '-XXaltjvm=<path>' option. Typical
      // value for buf is "<JAVA_HOME>/jre/lib/<vmtype>/libjvm.so".
      // If "/jre/lib/" appears at the right place in the string, then
      // assume we are installed in a JDK and we're done. Otherwise, check
      // for a JAVA_HOME environment variable and fix up the path so it
      // looks like libjvm.so is installed there (append a fake suffix
      // hotspot/libjvm.so).
      const char *p = buf + strlen(buf) - 1;
      for (int count = 0; p > buf && count < 4; ++count) {
        for (--p; p > buf && *p != '/'; --p)
          /* empty */ ;
      }
  
      if (strncmp(p, "/jre/lib/", 9) != 0) {
        // Look for JAVA_HOME in the environment.
        char* java_home_var = ::getenv("JAVA_HOME");
        if (java_home_var != NULL && java_home_var[0] != 0) {
          char* jrelib_p;
          int len;
  
          // Check the current module name "libjvm.so".
          p = strrchr(buf, '/');
          if (p == NULL) {
            return;
          }
          assert(strstr(p, "/libjvm") == p, "invalid library name");
  
          rp = os::Posix::realpath(java_home_var, buf, buflen);
          if (rp == NULL) {
            return;
          }
  
          // determine if this is a legacy image or modules image
          // modules image doesn't have "jre" subdirectory
          len = strlen(buf);
          assert(len < buflen, "Ran out of buffer room");
          jrelib_p = buf + len;
          snprintf(jrelib_p, buflen-len, "/jre/lib");
          if (0 != access(buf, F_OK)) {
            snprintf(jrelib_p, buflen-len, "/lib");
          }
  
          if (0 == access(buf, F_OK)) {
            // Use current module name "libjvm.so"
            len = strlen(buf);
            snprintf(buf + len, buflen-len, "/hotspot/libjvm.so");
          } else {
            // Go back to path of .so
            rp = os::Posix::realpath((char *)dlinfo.dli_fname, buf, buflen);
            if (rp == NULL) {
              return;
            }
          }
        }
      }
    }
  
    strncpy(saved_jvm_path, buf, sizeof(saved_jvm_path));
    saved_jvm_path[sizeof(saved_jvm_path) - 1] = '\0';
  }
  
  void os::print_jni_name_prefix_on(outputStream* st, int args_size) {
    // no prefix required, not even "_"
  }
  
  void os::print_jni_name_suffix_on(outputStream* st, int args_size) {
    // no suffix required
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  // Virtual Memory
  
  // We need to keep small simple bookkeeping for os::reserve_memory and friends.
  
  #define VMEM_MAPPED  1
  #define VMEM_SHMATED 2
  
  struct vmembk_t {
    int type;         // 1 - mmap, 2 - shmat
    char* addr;
    size_t size;      // Real size, may be larger than usersize.
    size_t pagesize;  // page size of area
    vmembk_t* next;
  
    bool contains_addr(char* p) const {
      return p >= addr && p < (addr + size);
    }
  
    bool contains_range(char* p, size_t s) const {
      return contains_addr(p) && contains_addr(p + s - 1);
    }
  
    void print_on(outputStream* os) const {
      os->print("[" PTR_FORMAT " - " PTR_FORMAT "] (" UINTX_FORMAT
        " bytes, %d %s pages), %s",
        addr, addr + size - 1, size, size / pagesize, describe_pagesize(pagesize),
        (type == VMEM_SHMATED ? "shmat" : "mmap")
      );
    }
  
    // Check that range is a sub range of memory block (or equal to memory block);
    // also check that range is fully page aligned to the page size if the block.
    void assert_is_valid_subrange(char* p, size_t s) const {
      if (!contains_range(p, s)) {
        trcVerbose("[" PTR_FORMAT " - " PTR_FORMAT "] is not a sub "
                "range of [" PTR_FORMAT " - " PTR_FORMAT "].",
                p2i(p), p2i(p + s), p2i(addr), p2i(addr + size));
        guarantee0(false);
      }
      if (!is_aligned_to(p, pagesize) || !is_aligned_to(p + s, pagesize)) {
        trcVerbose("range [" PTR_FORMAT " - " PTR_FORMAT "] is not"
                " aligned to pagesize (%lu)", p2i(p), p2i(p + s), (unsigned long) pagesize);
        guarantee0(false);
      }
    }
  };
  
  static struct {
    vmembk_t* first;
    MiscUtils::CritSect cs;
  } vmem;
  
  static void vmembk_add(char* addr, size_t size, size_t pagesize, int type) {
    vmembk_t* p = (vmembk_t*) ::malloc(sizeof(vmembk_t));
    assert0(p);
    if (p) {
      MiscUtils::AutoCritSect lck(&vmem.cs);
      p->addr = addr; p->size = size;
      p->pagesize = pagesize;
      p->type = type;
      p->next = vmem.first;
      vmem.first = p;
    }
  }
  
  static vmembk_t* vmembk_find(char* addr) {
    MiscUtils::AutoCritSect lck(&vmem.cs);
    for (vmembk_t* p = vmem.first; p; p = p->next) {
      if (p->addr <= addr && (p->addr + p->size) > addr) {
        return p;
      }
    }
    return NULL;
  }
  
  static void vmembk_remove(vmembk_t* p0) {
    MiscUtils::AutoCritSect lck(&vmem.cs);
    assert0(p0);
    assert0(vmem.first); // List should not be empty.
    for (vmembk_t** pp = &(vmem.first); *pp; pp = &((*pp)->next)) {
      if (*pp == p0) {
        *pp = p0->next;
        ::free(p0);
        return;
      }
    }
    assert0(false); // Not found?
  }
  
  static void vmembk_print_on(outputStream* os) {
    MiscUtils::AutoCritSect lck(&vmem.cs);
    for (vmembk_t* vmi = vmem.first; vmi; vmi = vmi->next) {
      vmi->print_on(os);
      os->cr();
    }
  }
  
  // Reserve and attach a section of System V memory.
  // If <requested_addr> is not NULL, function will attempt to attach the memory at the given
  // address. Failing that, it will attach the memory anywhere.
  // If <requested_addr> is NULL, function will attach the memory anywhere.
  static char* reserve_shmated_memory (size_t bytes, char* requested_addr) {
  
    trcVerbose("reserve_shmated_memory " UINTX_FORMAT " bytes, wishaddress "
      PTR_FORMAT "...", bytes, p2i(requested_addr));
  
    // We must prevent anyone from attaching too close to the
    // BRK because that may cause malloc OOM.
    if (requested_addr != NULL && is_close_to_brk((address)requested_addr)) {
      trcVerbose("Wish address " PTR_FORMAT " is too close to the BRK segment.", p2i(requested_addr));
      // Since we treat an attach to the wrong address as an error later anyway,
      // we return NULL here
      return NULL;
    }
  
    // For old AS/400's (V5R4 and older) we should not even be here - System V shared memory is not
    // really supported (max size 4GB), so reserve_mmapped_memory should have been used instead.
    if (os::Aix::on_pase_V5R4_or_older()) {
      ShouldNotReachHere();
    }
  
    // Align size of shm up to 64K to avoid errors if we later try to change the page size.
    const size_t size = align_up(bytes, 64*K);
  
    // Reserve the shared segment.
    int shmid = shmget(IPC_PRIVATE, size, IPC_CREAT | S_IRUSR | S_IWUSR);
    if (shmid == -1) {
      trcVerbose("shmget(.., " UINTX_FORMAT ", ..) failed (errno: %d).", size, errno);
      return NULL;
    }
  
    // Important note:
    // It is very important that we, upon leaving this function, do not leave a shm segment alive.
    // We must right after attaching it remove it from the system. System V shm segments are global and
    // survive the process.
    // So, from here on: Do not assert, do not return, until we have called shmctl(IPC_RMID) (A).
  
    struct shmid_ds shmbuf;
    memset(&shmbuf, 0, sizeof(shmbuf));
    shmbuf.shm_pagesize = 64*K;
    if (shmctl(shmid, SHM_PAGESIZE, &shmbuf) != 0) {
      trcVerbose("Failed to set page size (need " UINTX_FORMAT " 64K pages) - shmctl failed with %d.",
                 size / (64*K), errno);
      // I want to know if this ever happens.
      assert(false, "failed to set page size for shmat");
    }
  
    // Now attach the shared segment.
    // Note that I attach with SHM_RND - which means that the requested address is rounded down, if
    // needed, to the next lowest segment boundary. Otherwise the attach would fail if the address
    // were not a segment boundary.
    char* const addr = (char*) shmat(shmid, requested_addr, SHM_RND);
    const int errno_shmat = errno;
  
    // (A) Right after shmat and before handing shmat errors delete the shm segment.
    if (::shmctl(shmid, IPC_RMID, NULL) == -1) {
      trcVerbose("shmctl(%u, IPC_RMID) failed (%d)\n", shmid, errno);
      assert(false, "failed to remove shared memory segment!");
    }
  
    // Handle shmat error. If we failed to attach, just return.
    if (addr == (char*)-1) {
      trcVerbose("Failed to attach segment at " PTR_FORMAT " (%d).", p2i(requested_addr), errno_shmat);
      return NULL;
    }
  
    // Just for info: query the real page size. In case setting the page size did not
    // work (see above), the system may have given us something other then 4K (LDR_CNTRL).
    const size_t real_pagesize = os::Aix::query_pagesize(addr);
    if (real_pagesize != shmbuf.shm_pagesize) {
      trcVerbose("pagesize is, surprisingly, " SIZE_FORMAT, real_pagesize);
    }
  
    if (addr) {
      trcVerbose("shm-allocated " PTR_FORMAT " .. " PTR_FORMAT " (" UINTX_FORMAT " bytes, " UINTX_FORMAT " %s pages)",
        p2i(addr), p2i(addr + size - 1), size, size/real_pagesize, describe_pagesize(real_pagesize));
    } else {
      if (requested_addr != NULL) {
        trcVerbose("failed to shm-allocate " UINTX_FORMAT " bytes at with address " PTR_FORMAT ".", size, p2i(requested_addr));
      } else {
        trcVerbose("failed to shm-allocate " UINTX_FORMAT " bytes at any address.", size);
      }
    }
  
    // book-keeping
    vmembk_add(addr, size, real_pagesize, VMEM_SHMATED);
    assert0(is_aligned_to(addr, os::vm_page_size()));
  
    return addr;
  }
  
  static bool release_shmated_memory(char* addr, size_t size) {
  
    trcVerbose("release_shmated_memory [" PTR_FORMAT " - " PTR_FORMAT "].",
      p2i(addr), p2i(addr + size - 1));
  
    bool rc = false;
  
    // TODO: is there a way to verify shm size without doing bookkeeping?
    if (::shmdt(addr) != 0) {
      trcVerbose("error (%d).", errno);
    } else {
      trcVerbose("ok.");
      rc = true;
    }
    return rc;
  }
  
  static bool uncommit_shmated_memory(char* addr, size_t size) {
    trcVerbose("uncommit_shmated_memory [" PTR_FORMAT " - " PTR_FORMAT "].",
      p2i(addr), p2i(addr + size - 1));
  
    const bool rc = my_disclaim64(addr, size);
  
    if (!rc) {
      trcVerbose("my_disclaim64(" PTR_FORMAT ", " UINTX_FORMAT ") failed.\n", p2i(addr), size);
      return false;
    }
    return true;
  }
  
  ////////////////////////////////  mmap-based routines /////////////////////////////////
  
  // Reserve memory via mmap.
  // If <requested_addr> is given, an attempt is made to attach at the given address.
  // Failing that, memory is allocated at any address.
  static char* reserve_mmaped_memory(size_t bytes, char* requested_addr) {
    trcVerbose("reserve_mmaped_memory " UINTX_FORMAT " bytes, wishaddress " PTR_FORMAT "...",
      bytes, p2i(requested_addr));
  
    if (requested_addr && !is_aligned_to(requested_addr, os::vm_page_size()) != 0) {
      trcVerbose("Wish address " PTR_FORMAT " not aligned to page boundary.", p2i(requested_addr));
      return NULL;
    }
  
    // We must prevent anyone from attaching too close to the
    // BRK because that may cause malloc OOM.
    if (requested_addr != NULL && is_close_to_brk((address)requested_addr)) {
      trcVerbose("Wish address " PTR_FORMAT " is too close to the BRK segment.", p2i(requested_addr));
      // Since we treat an attach to the wrong address as an error later anyway,
      // we return NULL here
      return NULL;
    }
  
    // In 64K mode, we lie and claim the global page size (os::vm_page_size()) is 64K
    //  (complicated story). This mostly works just fine since 64K is a multiple of the
    //  actual 4K lowest page size. Only at a few seams light shines thru, e.g. when
    //  calling mmap. mmap will return memory aligned to the lowest pages size - 4K -
    //  so we must make sure - transparently - that the caller only ever sees 64K
    //  aligned mapping start addresses.
    const size_t alignment = os::vm_page_size();
  
    // Size shall always be a multiple of os::vm_page_size (esp. in 64K mode).
    const size_t size = align_up(bytes, os::vm_page_size());
  
    // alignment: Allocate memory large enough to include an aligned range of the right size and
    // cut off the leading and trailing waste pages.
    assert0(alignment != 0 && is_aligned_to(alignment, os::vm_page_size())); // see above
    const size_t extra_size = size + alignment;
  
    // Note: MAP_SHARED (instead of MAP_PRIVATE) needed to be able to
    // later use msync(MS_INVALIDATE) (see os::uncommit_memory).
    int flags = MAP_ANONYMOUS | MAP_SHARED;
  
    // MAP_FIXED is needed to enforce requested_addr - manpage is vague about what
    // it means if wishaddress is given but MAP_FIXED is not set.
    //
    // Important! Behaviour differs depending on whether SPEC1170 mode is active or not.
    // SPEC1170 mode active: behaviour like POSIX, MAP_FIXED will clobber existing mappings.
    // SPEC1170 mode not active: behaviour, unlike POSIX, is that no existing mappings will
    // get clobbered.
    if (requested_addr != NULL) {
      if (!os::Aix::xpg_sus_mode()) {  // not SPEC1170 Behaviour
        flags |= MAP_FIXED;
      }
    }
  
    char* addr = (char*)::mmap(requested_addr, extra_size,
        PROT_READ|PROT_WRITE|PROT_EXEC, flags, -1, 0);
  
    if (addr == MAP_FAILED) {
      trcVerbose("mmap(" PTR_FORMAT ", " UINTX_FORMAT ", ..) failed (%d)", p2i(requested_addr), size, errno);
      return NULL;
    } else if (requested_addr != NULL && addr != requested_addr) {
      trcVerbose("mmap(" PTR_FORMAT ", " UINTX_FORMAT ", ..) succeeded, but at a different address than requested (" PTR_FORMAT "), will unmap",
                 p2i(requested_addr), size, p2i(addr));
      ::munmap(addr, extra_size);
      return NULL;
    }
  
    // Handle alignment.
    char* const addr_aligned = align_up(addr, alignment);
    const size_t waste_pre = addr_aligned - addr;
    char* const addr_aligned_end = addr_aligned + size;
    const size_t waste_post = extra_size - waste_pre - size;
    if (waste_pre > 0) {
      ::munmap(addr, waste_pre);
    }
    if (waste_post > 0) {
      ::munmap(addr_aligned_end, waste_post);
    }
    addr = addr_aligned;
  
    trcVerbose("mmap-allocated " PTR_FORMAT " .. " PTR_FORMAT " (" UINTX_FORMAT " bytes)",
      p2i(addr), p2i(addr + bytes), bytes);
  
    // bookkeeping
    vmembk_add(addr, size, 4*K, VMEM_MAPPED);
  
    // Test alignment, see above.
    assert0(is_aligned_to(addr, os::vm_page_size()));
  
    return addr;
  }
  
  static bool release_mmaped_memory(char* addr, size_t size) {
    assert0(is_aligned_to(addr, os::vm_page_size()));
    assert0(is_aligned_to(size, os::vm_page_size()));
  
    trcVerbose("release_mmaped_memory [" PTR_FORMAT " - " PTR_FORMAT "].",
      p2i(addr), p2i(addr + size - 1));
    bool rc = false;
  
    if (::munmap(addr, size) != 0) {
      trcVerbose("failed (%d)\n", errno);
      rc = false;
    } else {
      trcVerbose("ok.");
      rc = true;
    }
  
    return rc;
  }
  
  static bool uncommit_mmaped_memory(char* addr, size_t size) {
  
    assert0(is_aligned_to(addr, os::vm_page_size()));
    assert0(is_aligned_to(size, os::vm_page_size()));
  
    trcVerbose("uncommit_mmaped_memory [" PTR_FORMAT " - " PTR_FORMAT "].",
      p2i(addr), p2i(addr + size - 1));
    bool rc = false;
  
    // Uncommit mmap memory with msync MS_INVALIDATE.
    if (::msync(addr, size, MS_INVALIDATE) != 0) {
      trcVerbose("failed (%d)\n", errno);
      rc = false;
    } else {
      trcVerbose("ok.");
      rc = true;
    }
  
    return rc;
  }
  
  int os::vm_page_size() {
    // Seems redundant as all get out.
    assert(os::Aix::page_size() != -1, "must call os::init");
    return os::Aix::page_size();
  }
  
  // Aix allocates memory by pages.
  int os::vm_allocation_granularity() {
    assert(os::Aix::page_size() != -1, "must call os::init");
    return os::Aix::page_size();
  }
  
  #ifdef PRODUCT
  static void warn_fail_commit_memory(char* addr, size_t size, bool exec,
                                      int err) {
    warning("INFO: os::commit_memory(" PTR_FORMAT ", " SIZE_FORMAT
            ", %d) failed; error='%s' (errno=%d)", p2i(addr), size, exec,
            os::errno_name(err), err);
  }
  #endif
  
  void os::pd_commit_memory_or_exit(char* addr, size_t size, bool exec,
                                    const char* mesg) {
    assert(mesg != NULL, "mesg must be specified");
    if (!pd_commit_memory(addr, size, exec)) {
      // Add extra info in product mode for vm_exit_out_of_memory():
      PRODUCT_ONLY(warn_fail_commit_memory(addr, size, exec, errno);)
      vm_exit_out_of_memory(size, OOM_MMAP_ERROR, "%s", mesg);
    }
  }
  
  bool os::pd_commit_memory(char* addr, size_t size, bool exec) {
  
    assert(is_aligned_to(addr, os::vm_page_size()),
      "addr " PTR_FORMAT " not aligned to vm_page_size (" PTR_FORMAT ")",
      p2i(addr), os::vm_page_size());
    assert(is_aligned_to(size, os::vm_page_size()),
      "size " PTR_FORMAT " not aligned to vm_page_size (" PTR_FORMAT ")",
      size, os::vm_page_size());
  
    vmembk_t* const vmi = vmembk_find(addr);
    guarantee0(vmi);
    vmi->assert_is_valid_subrange(addr, size);
  
    trcVerbose("commit_memory [" PTR_FORMAT " - " PTR_FORMAT "].", p2i(addr), p2i(addr + size - 1));
  
    if (UseExplicitCommit) {
      // AIX commits memory on touch. So, touch all pages to be committed.
      for (char* p = addr; p < (addr + size); p += 4*K) {
        *p = '\0';
      }
    }
  
    return true;
  }
  
  bool os::pd_commit_memory(char* addr, size_t size, size_t alignment_hint, bool exec) {
    return pd_commit_memory(addr, size, exec);
  }
  
  void os::pd_commit_memory_or_exit(char* addr, size_t size,
                                    size_t alignment_hint, bool exec,
                                    const char* mesg) {
    // Alignment_hint is ignored on this OS.
    pd_commit_memory_or_exit(addr, size, exec, mesg);
  }
  
  bool os::pd_uncommit_memory(char* addr, size_t size, bool exec) {
    assert(is_aligned_to(addr, os::vm_page_size()),
      "addr " PTR_FORMAT " not aligned to vm_page_size (" PTR_FORMAT ")",
      p2i(addr), os::vm_page_size());
    assert(is_aligned_to(size, os::vm_page_size()),
      "size " PTR_FORMAT " not aligned to vm_page_size (" PTR_FORMAT ")",
      size, os::vm_page_size());
  
    // Dynamically do different things for mmap/shmat.
    const vmembk_t* const vmi = vmembk_find(addr);
    guarantee0(vmi);
    vmi->assert_is_valid_subrange(addr, size);
  
    if (vmi->type == VMEM_SHMATED) {
      return uncommit_shmated_memory(addr, size);
    } else {
      return uncommit_mmaped_memory(addr, size);
    }
  }
  
  bool os::pd_create_stack_guard_pages(char* addr, size_t size) {
    // Do not call this; no need to commit stack pages on AIX.
    ShouldNotReachHere();
    return true;
  }
  
  bool os::remove_stack_guard_pages(char* addr, size_t size) {
    // Do not call this; no need to commit stack pages on AIX.
    ShouldNotReachHere();
    return true;
  }
  
  void os::pd_realign_memory(char *addr, size_t bytes, size_t alignment_hint) {
  }
  
  void os::pd_free_memory(char *addr, size_t bytes, size_t alignment_hint) {
  }
  
  void os::numa_make_global(char *addr, size_t bytes) {
  }
  
  void os::numa_make_local(char *addr, size_t bytes, int lgrp_hint) {
  }
  
  bool os::numa_topology_changed() {
    return false;
  }
  
  size_t os::numa_get_groups_num() {
    return 1;
  }
  
  int os::numa_get_group_id() {
    return 0;
  }
  
  size_t os::numa_get_leaf_groups(int *ids, size_t size) {
    if (size > 0) {
      ids[0] = 0;
      return 1;
    }
    return 0;
  }
  
  int os::numa_get_group_id_for_address(const void* address) {
    return 0;
  }
  
  bool os::get_page_info(char *start, page_info* info) {
    return false;
  }
  
  char *os::scan_pages(char *start, char* end, page_info* page_expected, page_info* page_found) {
    return end;
  }
  
  // Reserves and attaches a shared memory segment.
  char* os::pd_reserve_memory(size_t bytes, bool exec) {
    // Always round to os::vm_page_size(), which may be larger than 4K.
    bytes = align_up(bytes, os::vm_page_size());
  
    // In 4K mode always use mmap.
    // In 64K mode allocate small sizes with mmap, large ones with 64K shmatted.
    if (os::vm_page_size() == 4*K) {
      return reserve_mmaped_memory(bytes, NULL /* requested_addr */);
    } else {
      if (bytes >= Use64KPagesThreshold) {
        return reserve_shmated_memory(bytes, NULL /* requested_addr */);
      } else {
        return reserve_mmaped_memory(bytes, NULL /* requested_addr */);
      }
    }
  }
  
  bool os::pd_release_memory(char* addr, size_t size) {
  
    // Dynamically do different things for mmap/shmat.
    vmembk_t* const vmi = vmembk_find(addr);
    guarantee0(vmi);
    vmi->assert_is_valid_subrange(addr, size);
  
    // Always round to os::vm_page_size(), which may be larger than 4K.
    size = align_up(size, os::vm_page_size());
    addr = align_up(addr, os::vm_page_size());
  
    bool rc = false;
    bool remove_bookkeeping = false;
    if (vmi->type == VMEM_SHMATED) {
      // For shmatted memory, we do:
      // - If user wants to release the whole range, release the memory (shmdt).
      // - If user only wants to release a partial range, uncommit (disclaim) that
      //   range. That way, at least, we do not use memory anymore (bust still page
      //   table space).
      if (addr == vmi->addr && size == vmi->size) {
        rc = release_shmated_memory(addr, size);
        remove_bookkeeping = true;
      } else {
        rc = uncommit_shmated_memory(addr, size);
      }
    } else {
      // In mmap-mode:
      //  - If the user wants to release the full range, we do that and remove the mapping.
      //  - If the user wants to release part of the range, we release that part, but need
      //    to adjust bookkeeping.
      assert(is_aligned(size, 4 * K), "Sanity");
      rc = release_mmaped_memory(addr, size);
      if (addr == vmi->addr && size == vmi->size) {
        remove_bookkeeping = true;
      } else {
        if (addr == vmi->addr && size < vmi->size) {
          // Chopped from head
          vmi->addr += size;
          vmi->size -= size;
        } else if (addr + size == vmi->addr + vmi->size) {
          // Chopped from tail
          vmi->size -= size;
        } else {
          // releasing a mapping in the middle of the original mapping:
          // For now we forbid this, since this is an invalid scenario
          // (the bookkeeping is easy enough to fix if needed but there
          //  is no use case for it; any occurrence is likely an error.
          ShouldNotReachHere();
        }
      }
    }
  
    // update bookkeeping
    if (rc && remove_bookkeeping) {
      vmembk_remove(vmi);
    }
  
    return rc;
  }
  
  static bool checked_mprotect(char* addr, size_t size, int prot) {
  
    // Little problem here: if SPEC1170 behaviour is off, mprotect() on AIX will
    // not tell me if protection failed when trying to protect an un-protectable range.
    //
    // This means if the memory was allocated using shmget/shmat, protection wont work
    // but mprotect will still return 0:
    //
    // See http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.basetechref/doc/basetrf1/mprotect.htm
  
    Events::log(NULL, "Protecting memory [" INTPTR_FORMAT "," INTPTR_FORMAT "] with protection modes %x", p2i(addr), p2i(addr+size), prot);
    bool rc = ::mprotect(addr, size, prot) == 0 ? true : false;
  
    if (!rc) {
      const char* const s_errno = os::errno_name(errno);
      warning("mprotect(" PTR_FORMAT "-" PTR_FORMAT ", 0x%X) failed (%s).", addr, addr + size, prot, s_errno);
      return false;
    }
  
    // mprotect success check
    //
    // Mprotect said it changed the protection but can I believe it?
    //
    // To be sure I need to check the protection afterwards. Try to
    // read from protected memory and check whether that causes a segfault.
    //
    if (!os::Aix::xpg_sus_mode()) {
  
      if (CanUseSafeFetch32()) {
  
        const bool read_protected =
          (SafeFetch32((int*)addr, 0x12345678) == 0x12345678 &&
           SafeFetch32((int*)addr, 0x76543210) == 0x76543210) ? true : false;
  
        if (prot & PROT_READ) {
          rc = !read_protected;
        } else {
          rc = read_protected;
        }
  
        if (!rc) {
          if (os::Aix::on_pase()) {
            // There is an issue on older PASE systems where mprotect() will return success but the
            // memory will not be protected.
            // This has nothing to do with the problem of using mproect() on SPEC1170 incompatible
            // machines; we only see it rarely, when using mprotect() to protect the guard page of
            // a stack. It is an OS error.
            //
            // A valid strategy is just to try again. This usually works. :-/
  
            ::usleep(1000);
            Events::log(NULL, "Protecting memory [" INTPTR_FORMAT "," INTPTR_FORMAT "] with protection modes %x", p2i(addr), p2i(addr+size), prot);
            if (::mprotect(addr, size, prot) == 0) {
              const bool read_protected_2 =
                (SafeFetch32((int*)addr, 0x12345678) == 0x12345678 &&
                SafeFetch32((int*)addr, 0x76543210) == 0x76543210) ? true : false;
              rc = true;
            }
          }
        }
      }
    }
  
    assert(rc == true, "mprotect failed.");
  
    return rc;
  }
  
  // Set protections specified
  bool os::protect_memory(char* addr, size_t size, ProtType prot, bool is_committed) {
    unsigned int p = 0;
    switch (prot) {
    case MEM_PROT_NONE: p = PROT_NONE; break;
    case MEM_PROT_READ: p = PROT_READ; break;
    case MEM_PROT_RW:   p = PROT_READ|PROT_WRITE; break;
    case MEM_PROT_RWX:  p = PROT_READ|PROT_WRITE|PROT_EXEC; break;
    default:
      ShouldNotReachHere();
    }
    // is_committed is unused.
    return checked_mprotect(addr, size, p);
  }
  
  bool os::guard_memory(char* addr, size_t size) {
    return checked_mprotect(addr, size, PROT_NONE);
  }
  
  bool os::unguard_memory(char* addr, size_t size) {
    return checked_mprotect(addr, size, PROT_READ|PROT_WRITE|PROT_EXEC);
  }
  
  // Large page support
  
  static size_t _large_page_size = 0;
  
  // Enable large page support if OS allows that.
  void os::large_page_init() {
    return; // Nothing to do. See query_multipage_support and friends.
  }
  
  char* os::pd_reserve_memory_special(size_t bytes, size_t alignment, size_t page_size, char* req_addr, bool exec) {
    fatal("os::reserve_memory_special should not be called on AIX.");
    return NULL;
  }
  
  bool os::pd_release_memory_special(char* base, size_t bytes) {
    fatal("os::release_memory_special should not be called on AIX.");
    return false;
  }
  
  size_t os::large_page_size() {
    return _large_page_size;
  }
  
  bool os::can_commit_large_page_memory() {
    // Does not matter, we do not support huge pages.
    return false;
  }
  
  bool os::can_execute_large_page_memory() {
    // Does not matter, we do not support huge pages.
    return false;
  }
  
  char* os::pd_attempt_map_memory_to_file_at(char* requested_addr, size_t bytes, int file_desc) {
    assert(file_desc >= 0, "file_desc is not valid");
    char* result = NULL;
  
    // Always round to os::vm_page_size(), which may be larger than 4K.
    bytes = align_up(bytes, os::vm_page_size());
    result = reserve_mmaped_memory(bytes, requested_addr);
  
    if (result != NULL) {
      if (replace_existing_mapping_with_file_mapping(result, bytes, file_desc) == NULL) {
        vm_exit_during_initialization(err_msg("Error in mapping Java heap at the given filesystem directory"));
      }
    }
    return result;
  }
  
  // Reserve memory at an arbitrary address, only if that area is
  // available (and not reserved for something else).
  char* os::pd_attempt_reserve_memory_at(char* requested_addr, size_t bytes, bool exec) {
    char* addr = NULL;
  
    // Always round to os::vm_page_size(), which may be larger than 4K.
    bytes = align_up(bytes, os::vm_page_size());
  
    // In 4K mode always use mmap.
    // In 64K mode allocate small sizes with mmap, large ones with 64K shmatted.
    if (os::vm_page_size() == 4*K) {
      return reserve_mmaped_memory(bytes, requested_addr);
    } else {
      if (bytes >= Use64KPagesThreshold) {
        return reserve_shmated_memory(bytes, requested_addr);
      } else {
        return reserve_mmaped_memory(bytes, requested_addr);
      }
    }
  
    return addr;
  }
  
  // Sleep forever; naked call to OS-specific sleep; use with CAUTION
  void os::infinite_sleep() {
    while (true) {    // sleep forever ...
      ::sleep(100);   // ... 100 seconds at a time
    }
  }
  
  // Used to convert frequent JVM_Yield() to nops
  bool os::dont_yield() {
    return DontYieldALot;
  }
  
  void os::naked_yield() {
    sched_yield();
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  // thread priority support
  
  // From AIX manpage to pthread_setschedparam
  // (see: http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?
  //    topic=/com.ibm.aix.basetechref/doc/basetrf1/pthread_setschedparam.htm):
  //
  // "If schedpolicy is SCHED_OTHER, then sched_priority must be in the
  // range from 40 to 80, where 40 is the least favored priority and 80
  // is the most favored."
  //
  // (Actually, I doubt this even has an impact on AIX, as we do kernel
  // scheduling there; however, this still leaves iSeries.)
  //
  // We use the same values for AIX and PASE.
  int os::java_to_os_priority[CriticalPriority + 1] = {
    54,             // 0 Entry should never be used
  
    55,             // 1 MinPriority
    55,             // 2
    56,             // 3
  
    56,             // 4
    57,             // 5 NormPriority
    57,             // 6
  
    58,             // 7
    58,             // 8
    59,             // 9 NearMaxPriority
  
    60,             // 10 MaxPriority
  
    60              // 11 CriticalPriority
  };
  
  static int prio_init() {
    if (ThreadPriorityPolicy == 1) {
      if (geteuid() != 0) {
        if (!FLAG_IS_DEFAULT(ThreadPriorityPolicy) && !FLAG_IS_JIMAGE_RESOURCE(ThreadPriorityPolicy)) {
          warning("-XX:ThreadPriorityPolicy=1 may require system level permission, " \
                  "e.g., being the root user. If the necessary permission is not " \
                  "possessed, changes to priority will be silently ignored.");
        }
      }
    }
    if (UseCriticalJavaThreadPriority) {
      os::java_to_os_priority[MaxPriority] = os::java_to_os_priority[CriticalPriority];
    }
    return 0;
  }
  
  OSReturn os::set_native_priority(Thread* thread, int newpri) {
    if (!UseThreadPriorities || ThreadPriorityPolicy == 0) return OS_OK;
    pthread_t thr = thread->osthread()->pthread_id();
    int policy = SCHED_OTHER;
    struct sched_param param;
    param.sched_priority = newpri;
    int ret = pthread_setschedparam(thr, policy, &param);
  
    if (ret != 0) {
      trcVerbose("Could not change priority for thread %d to %d (error %d, %s)",
          (int)thr, newpri, ret, os::errno_name(ret));
    }
    return (ret == 0) ? OS_OK : OS_ERR;
  }
  
  OSReturn os::get_native_priority(const Thread* const thread, int *priority_ptr) {
    if (!UseThreadPriorities || ThreadPriorityPolicy == 0) {
      *priority_ptr = java_to_os_priority[NormPriority];
      return OS_OK;
    }
    pthread_t thr = thread->osthread()->pthread_id();
    int policy = SCHED_OTHER;
    struct sched_param param;
    int ret = pthread_getschedparam(thr, &policy, &param);
    *priority_ptr = param.sched_priority;
  
    return (ret == 0) ? OS_OK : OS_ERR;
  }
  
  // To install functions for atexit system call
  extern "C" {
    static void perfMemory_exit_helper() {
      perfMemory_exit();
    }
  }
  
  // This is called _before_ the most of global arguments have been parsed.
  void os::init(void) {
    // This is basic, we want to know if that ever changes.
    // (Shared memory boundary is supposed to be a 256M aligned.)
    assert(SHMLBA == ((uint64_t)0x10000000ULL)/*256M*/, "unexpected");
  
    // Record process break at startup.
    g_brk_at_startup = (address) ::sbrk(0);
    assert(g_brk_at_startup != (address) -1, "sbrk failed");
  
    // First off, we need to know whether we run on AIX or PASE, and
    // the OS level we run on.
    os::Aix::initialize_os_info();
  
    // Scan environment (SPEC1170 behaviour, etc).
    os::Aix::scan_environment();
  
    // Probe multipage support.
    query_multipage_support();
  
    // Act like we only have one page size by eliminating corner cases which
    // we did not support very well anyway.
    // We have two input conditions:
    // 1) Data segment page size. This is controlled by linker setting (datapsize) on the
    //    launcher, and/or by LDR_CNTRL environment variable. The latter overrules the linker
    //    setting.
    //    Data segment page size is important for us because it defines the thread stack page
    //    size, which is needed for guard page handling, stack banging etc.
    // 2) The ability to allocate 64k pages dynamically. If this is a given, java heap can
    //    and should be allocated with 64k pages.
    //
    // So, we do the following:
    // LDR_CNTRL    can_use_64K_pages_dynamically       what we do                      remarks
    // 4K           no                                  4K                              old systems (aix 5.2, as/400 v5r4) or new systems with AME activated
    // 4k           yes                                 64k (treat 4k stacks as 64k)    different loader than java and standard settings
    // 64k          no              --- AIX 5.2 ? ---
    // 64k          yes                                 64k                             new systems and standard java loader (we set datapsize=64k when linking)
  
    // We explicitly leave no option to change page size, because only upgrading would work,
    // not downgrading (if stack page size is 64k you cannot pretend its 4k).
  
    if (g_multipage_support.datapsize == 4*K) {
      // datapsize = 4K. Data segment, thread stacks are 4K paged.
      if (g_multipage_support.can_use_64K_pages) {
        // .. but we are able to use 64K pages dynamically.
        // This would be typical for java launchers which are not linked
        // with datapsize=64K (like, any other launcher but our own).
        //
        // In this case it would be smart to allocate the java heap with 64K
        // to get the performance benefit, and to fake 64k pages for the
        // data segment (when dealing with thread stacks).
        //
        // However, leave a possibility to downgrade to 4K, using
        // -XX:-Use64KPages.
        if (Use64KPages) {
          trcVerbose("64K page mode (faked for data segment)");
          Aix::_page_size = 64*K;
        } else {
          trcVerbose("4K page mode (Use64KPages=off)");
          Aix::_page_size = 4*K;
        }
      } else {
        // .. and not able to allocate 64k pages dynamically. Here, just
        // fall back to 4K paged mode and use mmap for everything.
        trcVerbose("4K page mode");
        Aix::_page_size = 4*K;
        FLAG_SET_ERGO(Use64KPages, false);
      }
    } else {
      // datapsize = 64k. Data segment, thread stacks are 64k paged.
      // This normally means that we can allocate 64k pages dynamically.
      // (There is one special case where this may be false: EXTSHM=on.
      // but we decided to not support that mode).
      assert0(g_multipage_support.can_use_64K_pages);
      Aix::_page_size = 64*K;
      trcVerbose("64K page mode");
      FLAG_SET_ERGO(Use64KPages, true);
    }
  
    // For now UseLargePages is just ignored.
    FLAG_SET_ERGO(UseLargePages, false);
    _page_sizes.add(Aix::_page_size);
  
    // debug trace
    trcVerbose("os::vm_page_size %s", describe_pagesize(os::vm_page_size()));
  
    // Next, we need to initialize libo4 and libperfstat libraries.
    if (os::Aix::on_pase()) {
      os::Aix::initialize_libo4();
    } else {
      os::Aix::initialize_libperfstat();
    }
  
    // Reset the perfstat information provided by ODM.
    if (os::Aix::on_aix()) {
      libperfstat::perfstat_reset();
    }
  
    // Now initialze basic system properties. Note that for some of the values we
    // need libperfstat etc.
    os::Aix::initialize_system_info();
  
    clock_tics_per_sec = sysconf(_SC_CLK_TCK);
  
    // _main_thread points to the thread that created/loaded the JVM.
    Aix::_main_thread = pthread_self();
  
    initial_time_count = javaTimeNanos();
  
    os::Posix::init();
  }
  
  // This is called _after_ the global arguments have been parsed.
  jint os::init_2(void) {
  
    // This could be set after os::Posix::init() but all platforms
    // have to set it the same so we have to mirror Solaris.
    DEBUG_ONLY(os::set_mutex_init_done();)
  
    os::Posix::init_2();
  
    if (os::Aix::on_pase()) {
      trcVerbose("Running on PASE.");
    } else {
      trcVerbose("Running on AIX (not PASE).");
    }
  
    trcVerbose("processor count: %d", os::_processor_count);
    trcVerbose("physical memory: %lu", Aix::_physical_memory);
  
    // Initially build up the loaded dll map.
    LoadedLibraries::reload();
    if (Verbose) {
      trcVerbose("Loaded Libraries: ");
      LoadedLibraries::print(tty);
    }
  
    if (PosixSignals::init() == JNI_ERR) {
      return JNI_ERR;
    }
  
    // Check and sets minimum stack sizes against command line options
    if (Posix::set_minimum_stack_sizes() == JNI_ERR) {
      return JNI_ERR;
    }
  
    // Not supported.
    FLAG_SET_ERGO(UseNUMA, false);
    FLAG_SET_ERGO(UseNUMAInterleaving, false);
  
    if (MaxFDLimit) {
      // Set the number of file descriptors to max. print out error
      // if getrlimit/setrlimit fails but continue regardless.
      struct rlimit nbr_files;
      int status = getrlimit(RLIMIT_NOFILE, &nbr_files);
      if (status != 0) {
        log_info(os)("os::init_2 getrlimit failed: %s", os::strerror(errno));
      } else {
        nbr_files.rlim_cur = nbr_files.rlim_max;
        status = setrlimit(RLIMIT_NOFILE, &nbr_files);
        if (status != 0) {
          log_info(os)("os::init_2 setrlimit failed: %s", os::strerror(errno));
        }
      }
    }
  
    if (PerfAllowAtExitRegistration) {
      // Only register atexit functions if PerfAllowAtExitRegistration is set.
      // At exit functions can be delayed until process exit time, which
      // can be problematic for embedded VM situations. Embedded VMs should
      // call DestroyJavaVM() to assure that VM resources are released.
  
      // Note: perfMemory_exit_helper atexit function may be removed in
      // the future if the appropriate cleanup code can be added to the
      // VM_Exit VMOperation's doit method.
      if (atexit(perfMemory_exit_helper) != 0) {
        warning("os::init_2 atexit(perfMemory_exit_helper) failed");
      }
    }
  
    // initialize thread priority policy
    prio_init();
  
    return JNI_OK;
  }
  
  int os::active_processor_count() {
    // User has overridden the number of active processors
    if (ActiveProcessorCount > 0) {
      log_trace(os)("active_processor_count: "
                    "active processor count set by user : %d",
                    ActiveProcessorCount);
      return ActiveProcessorCount;
    }
  
    int online_cpus = ::sysconf(_SC_NPROCESSORS_ONLN);
    assert(online_cpus > 0 && online_cpus <= processor_count(), "sanity check");
    return online_cpus;
  }
  
  void os::set_native_thread_name(const char *name) {
    // Not yet implemented.
    return;
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  // debug support
  
  bool os::find(address addr, outputStream* st) {
  
    st->print(PTR_FORMAT ": ", addr);
  
    loaded_module_t lm;
    if (LoadedLibraries::find_for_text_address(addr, &lm) != NULL ||
        LoadedLibraries::find_for_data_address(addr, &lm) != NULL) {
      st->print_cr("%s", lm.path);
      return true;
    }
  
    return false;
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  // misc
  
  // This does not do anything on Aix. This is basically a hook for being
  // able to use structured exception handling (thread-local exception filters)
  // on, e.g., Win32.
  void
  os::os_exception_wrapper(java_call_t f, JavaValue* value, const methodHandle& method,
                           JavaCallArguments* args, JavaThread* thread) {
    f(value, method, args, thread);
  }
  
  void os::print_statistics() {
  }
  
  bool os::message_box(const char* title, const char* message) {
    int i;
    fdStream err(defaultStream::error_fd());
    for (i = 0; i < 78; i++) err.print_raw("=");
    err.cr();
    err.print_raw_cr(title);
    for (i = 0; i < 78; i++) err.print_raw("-");
    err.cr();
    err.print_raw_cr(message);
    for (i = 0; i < 78; i++) err.print_raw("=");
    err.cr();
  
    char buf[16];
    // Prevent process from exiting upon "read error" without consuming all CPU
    while (::read(0, buf, sizeof(buf)) <= 0) { ::sleep(100); }
  
    return buf[0] == 'y' || buf[0] == 'Y';
  }
  
  // Is a (classpath) directory empty?
  bool os::dir_is_empty(const char* path) {
    DIR *dir = NULL;
    struct dirent *ptr;
  
    dir = opendir(path);
    if (dir == NULL) return true;
  
    /* Scan the directory */
    bool result = true;
    while (result && (ptr = readdir(dir)) != NULL) {
      if (strcmp(ptr->d_name, ".") != 0 && strcmp(ptr->d_name, "..") != 0) {
        result = false;
      }
    }
    closedir(dir);
    return result;
  }
  
  // This code originates from JDK's sysOpen and open64_w
  // from src/solaris/hpi/src/system_md.c
  
  int os::open(const char *path, int oflag, int mode) {
  
    if (strlen(path) > MAX_PATH - 1) {
      errno = ENAMETOOLONG;
      return -1;
    }
    // AIX 7.X now supports O_CLOEXEC too, like modern Linux; but we have to be careful, see
    // IV90804: OPENING A FILE IN AFS WITH O_CLOEXEC FAILS WITH AN EINVAL ERROR APPLIES TO AIX 7100-04 17/04/14 PTF PECHANGE
    int oflag_with_o_cloexec = oflag | O_CLOEXEC;
  
    int fd = ::open64(path, oflag_with_o_cloexec, mode);
    if (fd == -1) {
      // we might fail in the open call when O_CLOEXEC is set, so try again without (see IV90804)
      fd = ::open64(path, oflag, mode);
      if (fd == -1) {
        return -1;
      }
    }
  
    // If the open succeeded, the file might still be a directory.
    {
      struct stat64 buf64;
      int ret = ::fstat64(fd, &buf64);
      int st_mode = buf64.st_mode;
  
      if (ret != -1) {
        if ((st_mode & S_IFMT) == S_IFDIR) {
          errno = EISDIR;
          ::close(fd);
          return -1;
        }
      } else {
        ::close(fd);
        return -1;
      }
    }
  
    // All file descriptors that are opened in the JVM and not
    // specifically destined for a subprocess should have the
    // close-on-exec flag set. If we don't set it, then careless 3rd
    // party native code might fork and exec without closing all
    // appropriate file descriptors (e.g. as we do in closeDescriptors in
    // UNIXProcess.c), and this in turn might:
    //
    // - cause end-of-file to fail to be detected on some file
    //   descriptors, resulting in mysterious hangs, or
    //
    // - might cause an fopen in the subprocess to fail on a system
    //   suffering from bug 1085341.
  
    // Validate that the use of the O_CLOEXEC flag on open above worked.
    static sig_atomic_t O_CLOEXEC_is_known_to_work = 0;
    if (O_CLOEXEC_is_known_to_work == 0) {
      int flags = ::fcntl(fd, F_GETFD);
      if (flags != -1) {
        if ((flags & FD_CLOEXEC) != 0) {
          O_CLOEXEC_is_known_to_work = 1;
        } else { // it does not work
          ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
          O_CLOEXEC_is_known_to_work = -1;
        }
      }
    } else if (O_CLOEXEC_is_known_to_work == -1) {
      int flags = ::fcntl(fd, F_GETFD);
      if (flags != -1) {
        ::fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
      }
    }
  
    return fd;
  }
  
  // create binary file, rewriting existing file if required
  int os::create_binary_file(const char* path, bool rewrite_existing) {
    int oflags = O_WRONLY | O_CREAT;
    oflags |= rewrite_existing ? O_TRUNC : O_EXCL;
    return ::open64(path, oflags, S_IREAD | S_IWRITE);
  }
  
  // return current position of file pointer
  jlong os::current_file_offset(int fd) {
    return (jlong)::lseek64(fd, (off64_t)0, SEEK_CUR);
  }
  
  // move file pointer to the specified offset
  jlong os::seek_to_file_offset(int fd, jlong offset) {
    return (jlong)::lseek64(fd, (off64_t)offset, SEEK_SET);
  }
  
  // This code originates from JDK's sysAvailable
  // from src/solaris/hpi/src/native_threads/src/sys_api_td.c
  
  int os::available(int fd, jlong *bytes) {
    jlong cur, end;
    int mode;
    struct stat64 buf64;
  
    if (::fstat64(fd, &buf64) >= 0) {
      mode = buf64.st_mode;
      if (S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode)) {
        int n;
        if (::ioctl(fd, FIONREAD, &n) >= 0) {
          *bytes = n;
          return 1;
        }
      }
    }
    if ((cur = ::lseek64(fd, 0L, SEEK_CUR)) == -1) {
      return 0;
    } else if ((end = ::lseek64(fd, 0L, SEEK_END)) == -1) {
      return 0;
    } else if (::lseek64(fd, cur, SEEK_SET) == -1) {
      return 0;
    }
    *bytes = end - cur;
    return 1;
  }
  
  // Map a block of memory.
  char* os::pd_map_memory(int fd, const char* file_name, size_t file_offset,
                          char *addr, size_t bytes, bool read_only,
                          bool allow_exec) {
    int prot;
    int flags = MAP_PRIVATE;
  
    if (read_only) {
      prot = PROT_READ;
      flags = MAP_SHARED;
    } else {
      prot = PROT_READ | PROT_WRITE;
      flags = MAP_PRIVATE;
    }
  
    if (allow_exec) {
      prot |= PROT_EXEC;
    }
  
    if (addr != NULL) {
      flags |= MAP_FIXED;
    }
  
    // Allow anonymous mappings if 'fd' is -1.
    if (fd == -1) {
      flags |= MAP_ANONYMOUS;
    }
  
    char* mapped_address = (char*)::mmap(addr, (size_t)bytes, prot, flags,
                                       fd, file_offset);
    if (mapped_address == MAP_FAILED) {
      return NULL;
    }
    return mapped_address;
  }
  
  // Remap a block of memory.
  char* os::pd_remap_memory(int fd, const char* file_name, size_t file_offset,
                            char *addr, size_t bytes, bool read_only,
                            bool allow_exec) {
    // same as map_memory() on this OS
    return os::map_memory(fd, file_name, file_offset, addr, bytes, read_only,
                          allow_exec);
  }
  
  // Unmap a block of memory.
  bool os::pd_unmap_memory(char* addr, size_t bytes) {
    return munmap(addr, bytes) == 0;
  }
  
  // current_thread_cpu_time(bool) and thread_cpu_time(Thread*, bool)
  // are used by JVM M&M and JVMTI to get user+sys or user CPU time
  // of a thread.
  //
  // current_thread_cpu_time() and thread_cpu_time(Thread*) returns
  // the fast estimate available on the platform.
  
  jlong os::current_thread_cpu_time() {
    // return user + sys since the cost is the same
    const jlong n = os::thread_cpu_time(Thread::current(), true /* user + sys */);
    assert(n >= 0, "negative CPU time");
    return n;
  }
  
  jlong os::thread_cpu_time(Thread* thread) {
    // consistent with what current_thread_cpu_time() returns
    const jlong n = os::thread_cpu_time(thread, true /* user + sys */);
    assert(n >= 0, "negative CPU time");
    return n;
  }
  
  jlong os::current_thread_cpu_time(bool user_sys_cpu_time) {
    const jlong n = os::thread_cpu_time(Thread::current(), user_sys_cpu_time);
    assert(n >= 0, "negative CPU time");
    return n;
  }
  
  static bool thread_cpu_time_unchecked(Thread* thread, jlong* p_sys_time, jlong* p_user_time) {
    bool error = false;
  
    jlong sys_time = 0;
    jlong user_time = 0;
  
    // Reimplemented using getthrds64().
    //
    // Works like this:
    // For the thread in question, get the kernel thread id. Then get the
    // kernel thread statistics using that id.
    //
    // This only works of course when no pthread scheduling is used,
    // i.e. there is a 1:1 relationship to kernel threads.
    // On AIX, see AIXTHREAD_SCOPE variable.
  
    pthread_t pthtid = thread->osthread()->pthread_id();
  
    // retrieve kernel thread id for the pthread:
    tid64_t tid = 0;
    struct __pthrdsinfo pinfo;
    // I just love those otherworldly IBM APIs which force me to hand down
    // dummy buffers for stuff I dont care for...
    char dummy[1];
    int dummy_size = sizeof(dummy);
    if (pthread_getthrds_np(&pthtid, PTHRDSINFO_QUERY_TID, &pinfo, sizeof(pinfo),
                            dummy, &dummy_size) == 0) {
      tid = pinfo.__pi_tid;
    } else {
      tty->print_cr("pthread_getthrds_np failed.");
      error = true;
    }
  
    // retrieve kernel timing info for that kernel thread
    if (!error) {
      struct thrdentry64 thrdentry;
      if (getthrds64(getpid(), &thrdentry, sizeof(thrdentry), &tid, 1) == 1) {
        sys_time = thrdentry.ti_ru.ru_stime.tv_sec * 1000000000LL + thrdentry.ti_ru.ru_stime.tv_usec * 1000LL;
        user_time = thrdentry.ti_ru.ru_utime.tv_sec * 1000000000LL + thrdentry.ti_ru.ru_utime.tv_usec * 1000LL;
      } else {
        tty->print_cr("pthread_getthrds_np failed.");
        error = true;
      }
    }
  
    if (p_sys_time) {
      *p_sys_time = sys_time;
    }
  
    if (p_user_time) {
      *p_user_time = user_time;
    }
  
    if (error) {
      return false;
    }
  
    return true;
  }
  
  jlong os::thread_cpu_time(Thread *thread, bool user_sys_cpu_time) {
    jlong sys_time;
    jlong user_time;
  
    if (!thread_cpu_time_unchecked(thread, &sys_time, &user_time)) {
      return -1;
    }
  
    return user_sys_cpu_time ? sys_time + user_time : user_time;
  }
  
  void os::current_thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
    info_ptr->max_value = ALL_64_BITS;       // will not wrap in less than 64 bits
    info_ptr->may_skip_backward = false;     // elapsed time not wall time
    info_ptr->may_skip_forward = false;      // elapsed time not wall time
    info_ptr->kind = JVMTI_TIMER_TOTAL_CPU;  // user+system time is returned
  }
  
  void os::thread_cpu_time_info(jvmtiTimerInfo *info_ptr) {
    info_ptr->max_value = ALL_64_BITS;       // will not wrap in less than 64 bits
    info_ptr->may_skip_backward = false;     // elapsed time not wall time
    info_ptr->may_skip_forward = false;      // elapsed time not wall time
    info_ptr->kind = JVMTI_TIMER_TOTAL_CPU;  // user+system time is returned
  }
  
  bool os::is_thread_cpu_time_supported() {
    return true;
  }
  
  // System loadavg support. Returns -1 if load average cannot be obtained.
  // For now just return the system wide load average (no processor sets).
  int os::loadavg(double values[], int nelem) {
  
    guarantee(nelem >= 0 && nelem <= 3, "argument error");
    guarantee(values, "argument error");
  
    if (os::Aix::on_pase()) {
  
      // AS/400 PASE: use libo4 porting library
      double v[3] = { 0.0, 0.0, 0.0 };
  
      if (libo4::get_load_avg(v, v + 1, v + 2)) {
        for (int i = 0; i < nelem; i ++) {
          values[i] = v[i];
        }
        return nelem;
      } else {
        return -1;
      }
  
    } else {
  
      // AIX: use libperfstat
      libperfstat::cpuinfo_t ci;
      if (libperfstat::get_cpuinfo(&ci)) {
        for (int i = 0; i < nelem; i++) {
          values[i] = ci.loadavg[i];
        }
      } else {
        return -1;
      }
      return nelem;
    }
  }
  
  void os::pause() {
    char filename[MAX_PATH];
    if (PauseAtStartupFile && PauseAtStartupFile[0]) {
      jio_snprintf(filename, MAX_PATH, "%s", PauseAtStartupFile);
    } else {
      jio_snprintf(filename, MAX_PATH, "./vm.paused.%d", current_process_id());
    }
  
    int fd = ::open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
    if (fd != -1) {
      struct stat buf;
      ::close(fd);
      while (::stat(filename, &buf) == 0) {
        (void)::poll(NULL, 0, 100);
      }
    } else {
      trcVerbose("Could not open pause file '%s', continuing immediately.", filename);
    }
  }
  
  bool os::is_primordial_thread(void) {
    if (pthread_self() == (pthread_t)1) {
      return true;
    } else {
      return false;
    }
  }
  
  // OS recognitions (PASE/AIX, OS level) call this before calling any
  // one of Aix::on_pase(), Aix::os_version() static
  void os::Aix::initialize_os_info() {
  
    assert(_on_pase == -1 && _os_version == 0, "already called.");
  
    struct utsname uts;
    memset(&uts, 0, sizeof(uts));
    strcpy(uts.sysname, "?");
    if (::uname(&uts) == -1) {
      trcVerbose("uname failed (%d)", errno);
      guarantee(0, "Could not determine whether we run on AIX or PASE");
    } else {
      trcVerbose("uname says: sysname \"%s\" version \"%s\" release \"%s\" "
                 "node \"%s\" machine \"%s\"\n",
                 uts.sysname, uts.version, uts.release, uts.nodename, uts.machine);
      const int major = atoi(uts.version);
      assert(major > 0, "invalid OS version");
      const int minor = atoi(uts.release);
      assert(minor > 0, "invalid OS release");
      _os_version = (major << 24) | (minor << 16);
      char ver_str[20] = {0};
      const char* name_str = "unknown OS";
      if (strcmp(uts.sysname, "OS400") == 0) {
        // We run on AS/400 PASE. We do not support versions older than V5R4M0.
        _on_pase = 1;
        if (os_version_short() < 0x0504) {
          trcVerbose("OS/400 releases older than V5R4M0 not supported.");
          assert(false, "OS/400 release too old.");
        }
        name_str = "OS/400 (pase)";
        jio_snprintf(ver_str, sizeof(ver_str), "%u.%u", major, minor);
      } else if (strcmp(uts.sysname, "AIX") == 0) {
        // We run on AIX. We do not support versions older than AIX 7.1.
        _on_pase = 0;
        // Determine detailed AIX version: Version, Release, Modification, Fix Level.
        odmWrapper::determine_os_kernel_version(&_os_version);
        if (os_version_short() < 0x0701) {
          trcVerbose("AIX releases older than AIX 7.1 are not supported.");
          assert(false, "AIX release too old.");
        }
        name_str = "AIX";
        jio_snprintf(ver_str, sizeof(ver_str), "%u.%u.%u.%u",
                     major, minor, (_os_version >> 8) & 0xFF, _os_version & 0xFF);
      } else {
        assert(false, "%s", name_str);
      }
      trcVerbose("We run on %s %s", name_str, ver_str);
    }
  
    guarantee(_on_pase != -1 && _os_version, "Could not determine AIX/OS400 release");
  } // end: os::Aix::initialize_os_info()
  
  // Scan environment for important settings which might effect the VM.
  // Trace out settings. Warn about invalid settings and/or correct them.
  //
  // Must run after os::Aix::initialue_os_info().
  void os::Aix::scan_environment() {
  
    char* p;
    int rc;
  
    // Warn explicity if EXTSHM=ON is used. That switch changes how
    // System V shared memory behaves. One effect is that page size of
    // shared memory cannot be change dynamically, effectivly preventing
    // large pages from working.
    // This switch was needed on AIX 32bit, but on AIX 64bit the general
    // recommendation is (in OSS notes) to switch it off.
    p = ::getenv("EXTSHM");
    trcVerbose("EXTSHM=%s.", p ? p : "<unset>");
    if (p && strcasecmp(p, "ON") == 0) {
      _extshm = 1;
      trcVerbose("*** Unsupported mode! Please remove EXTSHM from your environment! ***");
      if (!AllowExtshm) {
        // We allow under certain conditions the user to continue. However, we want this
        // to be a fatal error by default. On certain AIX systems, leaving EXTSHM=ON means
        // that the VM is not able to allocate 64k pages for the heap.
        // We do not want to run with reduced performance.
        vm_exit_during_initialization("EXTSHM is ON. Please remove EXTSHM from your environment.");
      }
    } else {
      _extshm = 0;
    }
  
    // SPEC1170 behaviour: will change the behaviour of a number of POSIX APIs.
    // Not tested, not supported.
    //
    // Note that it might be worth the trouble to test and to require it, if only to
    // get useful return codes for mprotect.
    //
    // Note: Setting XPG_SUS_ENV in the process is too late. Must be set earlier (before
    // exec() ? before loading the libjvm ? ....)
    p = ::getenv("XPG_SUS_ENV");
    trcVerbose("XPG_SUS_ENV=%s.", p ? p : "<unset>");
    if (p && strcmp(p, "ON") == 0) {
      _xpg_sus_mode = 1;
      trcVerbose("Unsupported setting: XPG_SUS_ENV=ON");
      // This is not supported. Worst of all, it changes behaviour of mmap MAP_FIXED to
      // clobber address ranges. If we ever want to support that, we have to do some
      // testing first.
      guarantee(false, "XPG_SUS_ENV=ON not supported");
    } else {
      _xpg_sus_mode = 0;
    }
  
    if (os::Aix::on_pase()) {
      p = ::getenv("QIBM_MULTI_THREADED");
      trcVerbose("QIBM_MULTI_THREADED=%s.", p ? p : "<unset>");
    }
  
    p = ::getenv("LDR_CNTRL");
    trcVerbose("LDR_CNTRL=%s.", p ? p : "<unset>");
    if (os::Aix::on_pase() && os::Aix::os_version_short() == 0x0701) {
      if (p && ::strstr(p, "TEXTPSIZE")) {
        trcVerbose("*** WARNING - LDR_CNTRL contains TEXTPSIZE. "
          "you may experience hangs or crashes on OS/400 V7R1.");
      }
    }
  
    p = ::getenv("AIXTHREAD_GUARDPAGES");
    trcVerbose("AIXTHREAD_GUARDPAGES=%s.", p ? p : "<unset>");
  
  } // end: os::Aix::scan_environment()
  
  // PASE: initialize the libo4 library (PASE porting library).
  void os::Aix::initialize_libo4() {
    guarantee(os::Aix::on_pase(), "OS/400 only.");
    if (!libo4::init()) {
      trcVerbose("libo4 initialization failed.");
      assert(false, "libo4 initialization failed");
    } else {
      trcVerbose("libo4 initialized.");
    }
  }
  
  // AIX: initialize the libperfstat library.
  void os::Aix::initialize_libperfstat() {
    assert(os::Aix::on_aix(), "AIX only");
    if (!libperfstat::init()) {
      trcVerbose("libperfstat initialization failed.");
      assert(false, "libperfstat initialization failed");
    } else {
      trcVerbose("libperfstat initialized.");
    }
  }
  
  /////////////////////////////////////////////////////////////////////////////
  // thread stack
  
  // Get the current stack base from the OS (actually, the pthread library).
  // Note: usually not page aligned.
  address os::current_stack_base() {
    AixMisc::stackbounds_t bounds;
    bool rc = AixMisc::query_stack_bounds_for_current_thread(&bounds);
    guarantee(rc, "Unable to retrieve stack bounds.");
    return bounds.base;
  }
  
  // Get the current stack size from the OS (actually, the pthread library).
  // Returned size is such that (base - size) is always aligned to page size.
  size_t os::current_stack_size() {
    AixMisc::stackbounds_t bounds;
    bool rc = AixMisc::query_stack_bounds_for_current_thread(&bounds);
    guarantee(rc, "Unable to retrieve stack bounds.");
    // Align the returned stack size such that the stack low address
    // is aligned to page size (Note: base is usually not and we do not care).
    // We need to do this because caller code will assume stack low address is
    // page aligned and will place guard pages without checking.
    address low = bounds.base - bounds.size;
    address low_aligned = (address)align_up(low, os::vm_page_size());
    size_t s = bounds.base - low_aligned;
    return s;
  }
  
  // Get the default path to the core file
  // Returns the length of the string
  int os::get_core_path(char* buffer, size_t bufferSize) {
    const char* p = get_current_directory(buffer, bufferSize);
  
    if (p == NULL) {
      assert(p != NULL, "failed to get current directory");
      return 0;
    }
  
    jio_snprintf(buffer, bufferSize, "%s/core or core.%d",
                                                 p, current_process_id());
  
    return strlen(buffer);
  }
  
  bool os::start_debugging(char *buf, int buflen) {
    int len = (int)strlen(buf);
    char *p = &buf[len];
  
    jio_snprintf(p, buflen -len,
                   "\n\n"
                   "Do you want to debug the problem?\n\n"
                   "To debug, run 'dbx -a %d'; then switch to thread tid " INTX_FORMAT ", k-tid " INTX_FORMAT "\n"
                   "Enter 'yes' to launch dbx automatically (PATH must include dbx)\n"
                   "Otherwise, press RETURN to abort...",
                   os::current_process_id(),
                   os::current_thread_id(), thread_self());
  
    bool yes = os::message_box("Unexpected Error", buf);
  
    if (yes) {
      // yes, user asked VM to launch debugger
      jio_snprintf(buf, buflen, "dbx -a %d", os::current_process_id());
  
      os::fork_and_exec(buf);
      yes = false;
    }
    return yes;
  }
  
  static inline time_t get_mtime(const char* filename) {
    struct stat st;
    int ret = os::stat(filename, &st);
    assert(ret == 0, "failed to stat() file '%s': %s", filename, os::strerror(errno));
    return st.st_mtime;
  }
  
  int os::compare_file_modified_times(const char* file1, const char* file2) {
    time_t t1 = get_mtime(file1);
    time_t t2 = get_mtime(file2);
    return t1 - t2;
  }
  
  bool os::supports_map_sync() {
    return false;
  }
  
  void os::print_memory_mappings(char* addr, size_t bytes, outputStream* st) {}
  