linux.c

grub 1.95 linux 的bootloader 源代码

  if (grub_file_read (file, (char *) &lh, sizeof (lh)) != sizeof (lh))
    {
      grub_error (GRUB_ERR_READ_ERROR, "cannot read the linux header");
      goto fail;
    }

  if (lh.boot_flag != grub_cpu_to_le16 (0xaa55))
    {
      grub_error (GRUB_ERR_BAD_OS, "invalid magic number");
      goto fail;
    }

  if (lh.setup_sects > GRUB_LINUX_MAX_SETUP_SECTS)
    {
      grub_error (GRUB_ERR_BAD_OS, "too many setup sectors");
      goto fail;
    }

  /* EFI support is quite new, so reject old versions.  */
  if (lh.header != grub_cpu_to_le32 (GRUB_LINUX_MAGIC_SIGNATURE)
      || grub_le_to_cpu16 (lh.version) < 0x0203)
    {
      grub_error (GRUB_ERR_BAD_OS, "too old version");
      goto fail;
    }

  /* I'm not sure how to support zImage on EFI.  */
  if (! (lh.loadflags & GRUB_LINUX_FLAG_BIG_KERNEL))
    {
      grub_error (GRUB_ERR_BAD_OS, "zImage is not supported");
      goto fail;
    }

  setup_sects = lh.setup_sects;
  
  /* If SETUP_SECTS is not set, set it to the default (4).  */
  if (! setup_sects)
    setup_sects = GRUB_LINUX_DEFAULT_SETUP_SECTS;

  real_size = setup_sects << GRUB_DISK_SECTOR_BITS;
  prot_size = grub_file_size (file) - real_size - GRUB_DISK_SECTOR_SIZE;
  
  if (! allocate_pages (real_size, prot_size))
    goto fail;
  
  /* XXX Linux assumes that only elilo can boot Linux on EFI!!!  */
  lh.type_of_loader = 0x50;

  lh.cl_magic = GRUB_LINUX_CL_MAGIC;
  lh.cl_offset = GRUB_LINUX_CL_END_OFFSET;
  lh.cmd_line_ptr = (char *) real_mode_mem + GRUB_LINUX_CL_OFFSET;
  lh.ramdisk_image = 0;
  lh.ramdisk_size = 0;

  params = (struct linux_kernel_params *) &lh;

  /* These are not needed to be precise, because Linux uses these values
     only to raise an error when the decompression code cannot find good
     space.  */
  params->ext_mem = ((32 * 0x100000) >> 10);
  params->alt_mem = ((32 * 0x100000) >> 10);
  
  params->video_cursor_x = grub_efi_system_table->con_out->mode->cursor_column;
  params->video_cursor_y = grub_efi_system_table->con_out->mode->cursor_row;
  params->video_page = 0; /* ??? */
  params->video_mode = grub_efi_system_table->con_out->mode->mode;
  params->video_width = (grub_getwh () >> 8);
  params->video_ega_bx = 0;
  params->video_height = (grub_getwh () & 0xff);
  params->have_vga = 0;
  params->font_size = 16; /* XXX */

  /* No VBE on EFI.  */
  params->lfb_width = 0;
  params->lfb_height = 0;
  params->lfb_depth = 0;
  params->lfb_base = 0;
  params->lfb_size = 0;
  params->lfb_line_len = 0;
  params->red_mask_size = 0;
  params->red_field_pos = 0;
  params->green_mask_size = 0;
  params->green_field_pos = 0;
  params->blue_mask_size = 0;
  params->blue_field_pos = 0;
  params->reserved_mask_size = 0;
  params->reserved_field_pos = 0;
  params->vesapm_segment = 0;
  params->vesapm_offset = 0;
  params->lfb_pages = 0;
  params->vesa_attrib = 0;

  /* No APM on EFI.  */
  params->apm_version = 0;
  params->apm_code_segment = 0;
  params->apm_entry = 0;
  params->apm_16bit_code_segment = 0;
  params->apm_data_segment = 0;
  params->apm_flags = 0;
  params->apm_code_len = 0;
  params->apm_data_len = 0;

  /* XXX is there any way to use SpeedStep on EFI?  */
  params->ist_signature = 0;
  params->ist_command = 0;
  params->ist_event = 0;
  params->ist_perf_level = 0;

  /* Let the kernel probe the information.  */
  grub_memset (params->hd0_drive_info, 0, sizeof (params->hd0_drive_info));
  grub_memset (params->hd1_drive_info, 0, sizeof (params->hd1_drive_info));

  /* No MCA on EFI.  */
  params->rom_config_len = 0;

  params->efi_signature = GRUB_LINUX_EFI_SIGNATURE; /* XXX not used */
  params->efi_system_table = (grub_addr_t) grub_efi_system_table;
  /* The other EFI parameters are filled when booting.  */

  /* No need to fake the BIOS's memory map.  */
  params->mmap_size = 0;

  /* Let the kernel probe the information.  */
  params->ps_mouse = 0;

  /* Clear padding for future compatibility.  */
  grub_memset (params->padding1, 0, sizeof (params->padding1));
  grub_memset (params->padding2, 0, sizeof (params->padding2));
  grub_memset (params->padding3, 0, sizeof (params->padding3));
  grub_memset (params->padding4, 0, sizeof (params->padding4));
  grub_memset (params->padding5, 0, sizeof (params->padding5));
  grub_memset (params->padding6, 0, sizeof (params->padding6));
  grub_memset (params->padding7, 0, sizeof (params->padding7));
  grub_memset (params->padding8, 0, sizeof (params->padding8));
  grub_memset (params->padding9, 0, sizeof (params->padding9));
  
  /* Put the real mode code at the real location.  */
  grub_memmove (real_mode_mem, &lh, sizeof (lh));

  len = real_size + GRUB_DISK_SECTOR_SIZE - sizeof (lh);
  if (grub_file_read (file, (char *) real_mode_mem + sizeof (lh), len) != len)
    {
      grub_error (GRUB_ERR_FILE_READ_ERROR, "Couldn't read file");
      goto fail;
    }

  /* XXX there is no way to know if the kernel really supports EFI.  */
  grub_printf ("   [Linux-EFI, setup=0x%x, size=0x%x]\n",
	       real_size, prot_size);

  /* Detect explicitly specified memory size, if any.  */
  linux_mem_size = 0;
  for (i = 1; i < argc; i++)
    if (grub_memcmp (argv[i], "mem=", 4) == 0)
      {
	char *val = argv[i] + 4;
	  
	linux_mem_size = grub_strtoul (val, &val, 0);
	
	if (grub_errno)
	  {
	    grub_errno = GRUB_ERR_NONE;
	    linux_mem_size = 0;
	  }
	else
	  {
	    int shift = 0;
	    
	    switch (grub_tolower (val[0]))
	      {
	      case 'g':
		shift += 10;
	      case 'm':
		shift += 10;
	      case 'k':
		shift += 10;
	      default:
		break;
	      }

	    /* Check an overflow.  */
	    if (linux_mem_size > (~0UL >> shift))
	      linux_mem_size = 0;
	    else
	      linux_mem_size <<= shift;
	  }
      }

  /* Specify the boot file.  */
  dest = grub_stpcpy ((char *) real_mode_mem + GRUB_LINUX_CL_OFFSET,
		      "BOOT_IMAGE=");
  dest = grub_stpcpy (dest, argv[0]);
  
  /* Copy kernel parameters.  */
  for (i = 1;
       i < argc
	 && dest + grub_strlen (argv[i]) + 1 < ((char *) real_mode_mem
						+ GRUB_LINUX_CL_END_OFFSET);
       i++)
    {
      *dest++ = ' ';
      dest = grub_stpcpy (dest, argv[i]);
    }

  len = prot_size;
  if (grub_file_read (file, (char *) GRUB_LINUX_BZIMAGE_ADDR, len) != len)
    grub_error (GRUB_ERR_FILE_READ_ERROR, "Couldn't read file");

  if (grub_errno == GRUB_ERR_NONE)
    {
      grub_loader_set (grub_linux_boot, grub_linux_unload, 1);
      loaded = 1;
    }

 fail:
  
  if (file)
    grub_file_close (file);

  if (grub_errno != GRUB_ERR_NONE)
    {
      grub_dl_unref (my_mod);
      loaded = 0;
    }
}

void
grub_rescue_cmd_initrd (int argc, char *argv[])
{
  grub_file_t file = 0;
  grub_ssize_t size;
  grub_addr_t addr_min, addr_max;
  grub_addr_t addr;
  grub_efi_uintn_t mmap_size;
  grub_efi_memory_descriptor_t *desc;
  grub_efi_uintn_t desc_size;
  struct linux_kernel_header *lh;
  
  if (argc == 0)
    {
      grub_error (GRUB_ERR_BAD_ARGUMENT, "No module specified");
      goto fail;
    }
  
  if (! loaded)
    {
      grub_error (GRUB_ERR_BAD_ARGUMENT, "You need to load the kernel first.");
      goto fail;
    }

  file = grub_file_open (argv[0]);
  if (! file)
    goto fail;

  size = grub_file_size (file);
  initrd_pages = (page_align (size) >> 12);

  lh = (struct linux_kernel_header *) real_mode_mem;
  
  addr_max = grub_cpu_to_le32 (lh->initrd_addr_max);
  if (linux_mem_size != 0 && linux_mem_size < addr_max)
    addr_max = linux_mem_size;
  
  /* Linux 2.3.xx has a bug in the memory range check, so avoid
     the last page.
     Linux 2.2.xx has a bug in the memory range check, which is
     worse than that of Linux 2.3.xx, so avoid the last 64kb.  */
  addr_max -= 0x10000;

  /* Usually, the compression ratio is about 50%.  */
  addr_min = (grub_addr_t) prot_mode_mem + ((prot_mode_pages * 3) << 12);
  
  /* Find the highest address to put the initrd.  */
  mmap_size = find_mmap_size ();
  if (grub_efi_get_memory_map (&mmap_size, mmap_buf, 0, &desc_size, 0) <= 0)
    grub_fatal ("cannot get memory map");

  addr = 0;
  for (desc = mmap_buf;
       desc < NEXT_MEMORY_DESCRIPTOR (mmap_buf, mmap_size);
       desc = NEXT_MEMORY_DESCRIPTOR (desc, desc_size))
    {
      if (desc->type == GRUB_EFI_CONVENTIONAL_MEMORY
	  && desc->physical_start >= addr_min
	  && desc->physical_start + size < addr_max
	  && desc->num_pages >= initrd_pages)
	{
	  grub_efi_physical_address_t physical_end;
	  
	  physical_end = desc->physical_start + (desc->num_pages << 12);
	  if (physical_end > addr_max)
	    physical_end = addr_max;

	  if (physical_end > addr)
	    addr = physical_end - page_align (size);
	}
    }

  if (addr == 0)
    {
      grub_error (GRUB_ERR_OUT_OF_MEMORY, "no free pages available");
      goto fail;
    }
  
  initrd_mem = grub_efi_allocate_pages (addr, initrd_pages);
  if (! initrd_mem)
    grub_fatal ("cannot allocate pages");
  
  if (grub_file_read (file, initrd_mem, size) != size)
    {
      grub_error (GRUB_ERR_FILE_READ_ERROR, "Couldn't read file");
      goto fail;
    }

  grub_printf ("   [Initrd, addr=0x%x, size=0x%x]\n",
	       addr, size);
  
  lh->ramdisk_image = addr;
  lh->ramdisk_size = size;
  lh->root_dev = 0x0100; /* XXX */
  
 fail:
  if (file)
    grub_file_close (file);
}


GRUB_MOD_INIT(linux)
{
  grub_rescue_register_command ("linux",
				grub_rescue_cmd_linux,
				"load linux");
  grub_rescue_register_command ("initrd",
				grub_rescue_cmd_initrd,
				"load initrd");
  my_mod = mod;
}

GRUB_MOD_FINI(linux)
{
  grub_rescue_unregister_command ("linux");
  grub_rescue_unregister_command ("initrd");
}