text: // x86 trap and interrupt constants.
  
  // Processor-defined:
  #define T_DIVIDE         0      // divide error
  #define T_DEBUG          1      // debug exception
  #define T_NMI            2      // non-maskable interrupt
  #define T_BRKPT          3      // breakpoint
  #define T_OFLOW          4      // overflow
  #define T_BOUND          5      // bounds check
  #define T_ILLOP          6      // illegal opcode
  #define T_DEVICE         7      // device not available
  #define T_DBLFLT         8      // double fault
  // #define T_COPROC      9      // reserved (not used since 486)
  #define T_TSS           10      // invalid task switch segment
  #define T_SEGNP         11      // segment not present
  #define T_STACK         12      // stack exception
  #define T_GPFLT         13      // general protection fault
  #define T_PGFLT         14      // page fault
  // #define T_RES        15      // reserved
  #define T_FPERR         16      // floating point error
  #define T_ALIGN         17      // aligment check
  #define T_MCHK          18      // machine check
  #define T_SIMDERR       19      // SIMD floating point error
  
  // These are arbitrarily chosen, but with care not to overlap
  // processor defined exceptions or interrupt vectors.
  #define T_SYSCALL       64      // system call
  #define T_DEFAULT      500      // catchall
  
  #define T_IRQ0          32      // IRQ 0 corresponds to int T_IRQ
  
  #define IRQ_TIMER        0
  #define IRQ_KBD          1
  #define IRQ_COM1         4
  #define IRQ_IDE         14
  #define IRQ_ERROR       19
  #define IRQ_SPURIOUS    31
  
  /* 
    缺页中断时的错误码
  	https://wiki.osdev.org/Exceptions#Page_Fault 中有详细说明
  */
  #define PGFLT_P          1
  #define PGFLT_WR         2
  #define PGFLT_US         4
  #define PGFLT_RSVD       8
  #define PGFLT_ID        16
  