text: /*
  ** Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
  ** Distributed under the terms of the NewOS License.
  */
  #ifndef _KERNEL_ARCH_PPC_KERNEL_H
  #define _KERNEL_ARCH_PPC_KERNEL_H
  
  #include <arch/cpu.h>
  
  // memory layout
  #define KERNEL_BASE 0x80000000
  #define KERNEL_SIZE 0x80000000
  #define KERNEL_TOP  (KERNEL_BASE + (KERNEL_SIZE - 1))
  
  /*
  ** User space layout is a little special:
  ** The user space does not completely cover the space not covered by the kernel.
  ** This is accomplished by starting user space at 1Mb and running to 64kb short of kernel space.
  ** The lower 1Mb reserved spot makes it easy to find null pointer references and guarantees a
  ** region wont be placed there. The 64kb region assures a user space thread cannot pass
  ** a buffer into the kernel as part of a syscall that would cross into kernel space.
  */
  #define USER_BASE     0x100000
  #define USER_BASE_ANY USER_BASE
  #define USER_SIZE     (0x80000000 - (0x10000 + USER_BASE))
  #define USER_TOP      (USER_BASE + (USER_SIZE - 1))
  
  #define KERNEL_USER_DATA_BASE	0x60000000
  #define USER_STACK_REGION              0x70000000
  #define USER_STACK_REGION_SIZE ((USER_TOP - USER_STACK_REGION) + 1)
  
  #endif	/* _KERNEL_ARCH_PPC_KERNEL_H */
  