core/init.c

   1 #include <core.h>
   2 #include <com32.h>
   3 #include <sys/io.h>
   4 #include <fs.h>
   5 #include <bios.h>
   6
   7 static uint32_t min_lowmem_heap = 65536;
   8 extern char __lowmem_heap[];
   9 uint8_t KbdFlags;               /* Check for keyboard escapes */
  10 __export uint8_t KbdMap[256];   /* Keyboard map */
  11
  12 __export uint16_t PXERetry;
  13
  14 static inline void check_escapes(void)
  15 {
  16         com32sys_t ireg, oreg;
  17
  18         ireg.eax.b[1] = 0x02;   /* Check keyboard flags */
  19         __intcall(0x16, &ireg, &oreg);
  20
  21         KbdFlags = oreg.eax.b[0];
  22
  23         /* Ctrl->skip 386 check */
  24         if (oreg.eax.b[0] & 0x04) {
  25                 /*
  26                  * Now check that there is sufficient low (DOS) memory
  27                  *
  28                  * NOTE: Linux doesn't use all of real_mode_seg, but we use
  29                  * the same segment for COMBOOT images, which can use all 64K.
  30                  */
  31                 uint16_t mem;
  32
  33                 __intcall(0x12, &ireg, &oreg);
  34
  35                 mem = ((uint32_t)__lowmem_heap) + min_lowmem_heap + 1023;
  36                 mem = mem >> 10;
  37
  38                 if (mem < oreg.eax.w[0]) {
  39                         char buf[256];
  40
  41                         snprintf(buf, sizeof(buf),
  42                                  "It appears your computer has only "
  43                                  "%dK of low (\"DOS\") RAM.\n"
  44                                  "This version of Syslinux needs "
  45                                  "%dK to boot.  "
  46                                  "If you get this\nmessage in error, "
  47                                  "hold down the Ctrl key while booting, "
  48                                  "and I\nwill take your word for it.\n",
  49                                  oreg.eax.w[0], mem);
  50                         writestr(buf);
  51                         kaboom();
  52                 }
  53         }
  54 }
  55
  56 extern uint32_t BIOS_timer_next;
  57 extern uint32_t timer_irq;
  58 static inline void bios_timer_init(void)
  59 {
  60         unsigned long next;
  61         uint32_t *hook = (uint32_t *)BIOS_timer_hook;
  62
  63         next = *hook;
  64         BIOS_timer_next = next;
  65         *hook = (uint32_t)&timer_irq;
  66 }
  67
  68 void init(com32sys_t *regs __unused)
  69 {
  70         int i;
  71
  72         /* Initialize timer */
  73         bios_timer_init();
  74
  75         for (i = 0; i < 256; i++)
  76                 KbdMap[i] = i;
  77
  78         adjust_screen();
  79
  80         /* CPU-dependent initialization and related checks. */
  81         check_escapes();
  82 }