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
  11 static inline void check_escapes(void)
  12 {
  13         com32sys_t ireg, oreg;
  14
  15         ireg.eax.b[1] = 0x02;   /* Check keyboard flags */
  16         __intcall(0x16, &ireg, &oreg);
  17
  18         KbdFlags = oreg.eax.b[0];
  19
  20         /* Ctrl->skip 386 check */
  21         if (oreg.eax.b[0] & 0x04) {
  22                 /*
  23                  * Now check that there is sufficient low (DOS) memory
  24                  *
  25                  * NOTE: Linux doesn't use all of real_mode_seg, but we use
  26                  * the same segment for COMBOOT images, which can use all 64K.
  27                  */
  28                 uint16_t mem;
  29
  30                 __intcall(0x12, &ireg, &oreg);
  31
  32                 mem = ((uint32_t)__lowmem_heap) + min_lowmem_heap + 1023;
  33                 mem = mem >> 10;
  34
  35                 if (mem < oreg.eax.w[0]) {
  36                         char buf[256];
  37
  38                         snprintf(buf, sizeof(buf),
  39                                  "It appears you computer has less than "
  40                                  "%dK of low (DOS)\nRAM.  Syslinux "
  41                                  "needs at least this amount to boot.  "
  42                                  "If you get\nthis message in error, "
  43                                  "hold down the Ctrl key while\nbooting, "
  44                                  "and I will take your word for it.\n",
  45                                  mem);
  46                         writestr(buf);
  47                         kaboom();
  48                 }
  49         }
  50 }
  51
  52 extern uint32_t BIOS_timer_next;
  53 extern uint32_t timer_irq;
  54 static inline void bios_timer_init(void)
  55 {
  56         unsigned long next;
  57         uint32_t *hook = (uint32_t *)BIOS_timer_hook;
  58
  59         next = *hook;
  60         BIOS_timer_next = next;
  61         *hook = (uint32_t)&timer_irq;
  62 }
  63
  64 extern void printf_init(void);
  65 void init(com32sys_t *regs __unused)
  66 {
  67         int i;
  68
  69         /* Initialize timer */
  70         bios_timer_init();
  71
  72         for (i = 0; i < 256; i++)
  73                 KbdMap[i] = i;
  74
  75         adjust_screen();
  76         printf_init();
  77
  78         /* Init the memory subsystem */
  79         mem_init();
  80
  81         /* CPU-dependent initialization and related checks. */
  82         check_escapes();
  83 }