memdisk/msetup.c

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2001-2003 H. Peter Anvin - All Rights Reserved
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
 *   Boston MA 02111-1307, USA; either version 2 of the License, or
 *   (at your option) any later version; incorporated herein by reference.
 *
 * ----------------------------------------------------------------------- */

/*
 * msetup.c
 *
 * Initialization code for memory-based disk
 */

#include <stdint.h>
#include "memdisk.h"
#include "conio.h"
#include "e820.h"

static inline int get_e820(void)
{
  struct e820_info {
    uint64_t base;
    uint64_t len;
    uint32_t type;
  } *buf = sys_bounce;
  uint32_t copied;
  int range_count = 0;
  com32sys_t regs;

  memset(&regs, 0, sizeof regs);

  do {
    regs.eax.l = 0x0000e820;
    regs.ecx.l = sizeof(*buf);
    regs.edx.l = 0x534d4150;
    regs.edi.w[0] = OFFS(buf);
    regs.es = SEG(buf);

    syscall(0x15, &regs, &regs);
    copied = (regs.eflags.l & 1) ? 0 : regs.ecx.l;

    if ( regs.eax.l != 0x534d4150 || copied < 20 )
      break;

    printf("e820: %08x%08x %08x%08x %d\n",
	   (uint32_t)(buf->base >> 32), (uint32_t)buf->base,
	   (uint32_t)(buf->len >> 32), (uint32_t)buf->len,
	   buf->type);

    insertrange(buf->base, buf->len, buf->type);
    range_count++;

  } while ( regs.ebx.l );

  return !range_count;
}

static inline void get_dos_mem(void)
{
  com32sys_t regs;

  memset(&regs, 0, sizeof regs);
  syscall(0x12, &regs, &regs);
  insertrange(0, (uint64_t)((uint32_t)regs.eax.w[0] << 10), 1);
  printf(" DOS: %d K\n", regs.eax.w[0]);
}

static inline int get_e801(void)
{
  int err;
  com32sys_t regs;

  memset(&regs, 0, sizeof regs);

  regs.eax.w[0] = 0xe801;
  syscall(0x15, &regs, &regs);

  if ( !(err = regs.eflags.l & 1) ) {
    if ( regs.eax.w[0] ) {
      insertrange(0x100000, (uint64_t)((uint32_t)regs.eax.w[0] << 10), 1);
    }
    if ( regs.ebx.w[0] ) {
      insertrange(0x1000000, (uint64_t)((uint32_t)regs.ebx.w[0] << 16), 1);
    }

    printf("e801: %04x %04x\n", regs.eax.w[0], regs.ebx.w[0]);
  }

  return err;
}

static inline int get_88(void)
{
  com32sys_t regs;
  int err;

  memset(&regs, 0, sizeof regs);

  regs.eax.b[1] = 0x88;
  syscall(0x15, &regs, &regs);


  if ( !(err = regs.eflags.l & 1) ) {
    if ( regs.eax.w[0] ) {
      insertrange(0x100000, (uint64_t)((uint32_t)regs.eax.w[0] << 10), 1);
    }

    printf("  88: %04x\n", regs.eax.w[0]);
  }

  return err;
}

uint32_t dos_mem  = 0;		/* 0-1MB */
uint32_t low_mem  = 0;		/* 1-16MB */
uint32_t high_mem = 0;		/* 16+ MB */

void get_mem(void)
{
  if ( get_e820() ) {
    get_dos_mem();
    if ( get_e801() ) {
      if ( get_88() ) {
	puts("MEMDISK: Unable to obtain memory map\n");
	die();
      }
    }
  }
}

#define PW(x) (1ULL << (x))

void parse_mem(void)
{
  struct e820range *ep;

  dos_mem = low_mem = high_mem = 0;

  /* Derive "dos mem", "high mem", and "low mem" from the range array */
  for ( ep = ranges ; ep->type != -1 ; ep++ ) {
    if ( ep->type == 1 ) {
      /* Only look at memory ranges */
      if ( ep->start == 0 ) {
	if ( ep[1].start > PW(20) )
	  dos_mem = PW(20);
	else
	  dos_mem = ep[1].start;
      }
      if ( ep->start <= PW(20) && ep[1].start > PW(20) ) {
	if ( ep[1].start > PW(24) )
	  low_mem = PW(24) - PW(20);
	else
	  low_mem = ep[1].start - PW(20);
      }
      if ( ep->start <= PW(24) && ep[1].start > PW(24) ) {
	if ( ep[1].start > PW(32) )
	  high_mem = PW(32) - PW(24);
	else
	  high_mem = ep[1].start - PW(24);
      }
    }
  }
}