grub-lakitu/grub-core/loader/i386/pc/linux.c - cos/cobble - Git at Google

 /* linux.c - boot Linux zImage or bzImage */
 /*
  *  GRUB  --  GRand Unified Bootloader
  *  Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2007,2008,2009,2010  Free Software Foundation, Inc.
  *
  *  GRUB 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, either version 3 of the License, or
  *  (at your option) any later version.
  *
  *  GRUB is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <grub/loader.h>
 #include <grub/file.h>
 #include <grub/err.h>
 #include <grub/device.h>
 #include <grub/disk.h>
 #include <grub/misc.h>
 #include <grub/types.h>
 #include <grub/memory.h>
 #include <grub/dl.h>
 #include <grub/cpu/linux.h>
 #include <grub/command.h>
 #include <grub/i18n.h>
 #include <grub/mm.h>
 #include <grub/cpu/relocator.h>
 #include <grub/video.h>
 #include <grub/i386/floppy.h>
 #include <grub/lib/cmdline.h>
 #include <grub/linux.h>
 #include <grub/efi/sb.h>

 GRUB_MOD_LICENSE ("GPLv3+");

 #define GRUB_LINUX_CL_OFFSET		0x9000

 static grub_dl_t my_mod;

 static grub_size_t linux_mem_size;
 static int loaded;
 static struct grub_relocator *relocator = NULL;
 static grub_addr_t grub_linux_real_target;
 static char *grub_linux_real_chunk;
 static grub_size_t grub_linux16_prot_size;
 static grub_size_t maximal_cmdline_size;

 static grub_err_t
 grub_linux16_boot (void)
 {
   grub_uint16_t segment;
   struct grub_relocator16_state state;

   segment = grub_linux_real_target >> 4;
   state.gs = state.fs = state.es = state.ds = state.ss = segment;
   state.sp = GRUB_LINUX_SETUP_STACK;
   state.cs = segment + 0x20;
   state.ip = 0;
   state.a20 = 1;

   grub_video_set_mode ("text", 0, 0);

   grub_stop_floppy ();

   return grub_relocator16_boot (relocator, state);
 }

 static grub_err_t
 grub_linux_unload (void)
 {
   grub_dl_unref (my_mod);
   loaded = 0;
   grub_relocator_unload (relocator);
   relocator = NULL;
   return GRUB_ERR_NONE;
 }

 static int
 target_hook (grub_uint64_t addr, grub_uint64_t size, grub_memory_type_t type,
 	    void *data)
 {
   grub_uint64_t *result = data;
   grub_uint64_t candidate;

   if (type != GRUB_MEMORY_AVAILABLE)
     return 0;
   if (addr >= 0xa0000)
     return 0;
   if (addr + size >= 0xa0000)
     size = 0xa0000 - addr;

   /* Put the real mode part at as a high location as possible.  */
   candidate = addr + size - (GRUB_LINUX_CL_OFFSET + maximal_cmdline_size);
   /* But it must not exceed the traditional area.  */
   if (candidate > GRUB_LINUX_OLD_REAL_MODE_ADDR)
     candidate = GRUB_LINUX_OLD_REAL_MODE_ADDR;
   if (candidate < addr)
     return 0;

   if (candidate > *result || *result == (grub_uint64_t) -1)
     *result = candidate;
   return 0;
 }

 static grub_addr_t
 grub_find_real_target (void)
 {
   grub_uint64_t result = (grub_uint64_t) -1;

   grub_mmap_iterate (target_hook, &result);
   return result;
 }

 static grub_err_t
 grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
 		int argc, char *argv[])
 {
   grub_file_t file = 0;
   struct linux_kernel_header lh;
   grub_uint8_t setup_sects;
   grub_size_t real_size;
   grub_ssize_t len;
   int i;
   char *grub_linux_prot_chunk;
   int grub_linux_is_bzimage;
   grub_addr_t grub_linux_prot_target;
   grub_err_t err;

   grub_dl_ref (my_mod);

   if (argc == 0)
     {
       grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
       goto fail;
     }

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

   if (grub_file_read (file, &lh, sizeof (lh)) != sizeof (lh))
     {
       if (!grub_errno)
 	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
 		    argv[0]);
       goto fail;
     }

   if (lh.boot_flag != grub_cpu_to_le16_compile_time (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;
     }

   grub_linux_is_bzimage = 0;
   setup_sects = lh.setup_sects;
   linux_mem_size = 0;

   maximal_cmdline_size = 256;

   if (lh.header == grub_cpu_to_le32_compile_time (GRUB_LINUX_MAGIC_SIGNATURE)
       && grub_le_to_cpu16 (lh.version) >= 0x0200)
     {
       grub_linux_is_bzimage = (lh.loadflags & GRUB_LINUX_FLAG_BIG_KERNEL);
       lh.type_of_loader = GRUB_LINUX_BOOT_LOADER_TYPE;

       if (grub_le_to_cpu16 (lh.version) >= 0x0206)
 	maximal_cmdline_size = grub_le_to_cpu32 (lh.cmdline_size) + 1;

       grub_linux_real_target = grub_find_real_target ();
       if (grub_linux_real_target == (grub_addr_t)-1)
 	{
 	  grub_error (GRUB_ERR_OUT_OF_RANGE,
 		      "no appropriate low memory found");
 	  goto fail;
 	}

       if (grub_le_to_cpu16 (lh.version) >= 0x0201)
 	{
 	  lh.heap_end_ptr = grub_cpu_to_le16_compile_time (GRUB_LINUX_HEAP_END_OFFSET);
 	  lh.loadflags |= GRUB_LINUX_FLAG_CAN_USE_HEAP;
 	}

       if (grub_le_to_cpu16 (lh.version) >= 0x0202)
 	lh.cmd_line_ptr = grub_linux_real_target + GRUB_LINUX_CL_OFFSET;
       else
 	{
 	  lh.cl_magic = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_MAGIC);
 	  lh.cl_offset = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_OFFSET);
 	  lh.setup_move_size = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_OFFSET
 						 + maximal_cmdline_size);
 	}
     }
   else
     {
       /* Your kernel is quite old...  */
       lh.cl_magic = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_MAGIC);
       lh.cl_offset = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_OFFSET);

       setup_sects = GRUB_LINUX_DEFAULT_SETUP_SECTS;

       grub_linux_real_target = GRUB_LINUX_OLD_REAL_MODE_ADDR;
     }

   /* 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;
   grub_linux16_prot_size = grub_file_size (file)
     - real_size - GRUB_DISK_SECTOR_SIZE;

   if (! grub_linux_is_bzimage
       && GRUB_LINUX_ZIMAGE_ADDR + grub_linux16_prot_size
       > grub_linux_real_target)
     {
       grub_error (GRUB_ERR_BAD_OS, "too big zImage (0x%x > 0x%x), use bzImage instead",
 		  (char *) GRUB_LINUX_ZIMAGE_ADDR + grub_linux16_prot_size,
 		  (grub_size_t) grub_linux_real_target);
       goto fail;
     }

   grub_dprintf ("linux", "[Linux-%s, setup=0x%x, size=0x%x]\n",
 		grub_linux_is_bzimage ? "bzImage" : "zImage",
 		(unsigned) real_size,
 		(unsigned) grub_linux16_prot_size);

   relocator = grub_relocator_new ();
   if (!relocator)
     goto fail;

   for (i = 1; i < argc; i++)
     if (grub_memcmp (argv[i], "vga=", 4) == 0)
       {
 	/* Video mode selection support.  */
 	grub_uint16_t vid_mode;
 	char *val = argv[i] + 4;

 	if (grub_strcmp (val, "normal") == 0)
 	  vid_mode = GRUB_LINUX_VID_MODE_NORMAL;
 	else if (grub_strcmp (val, "ext") == 0)
 	  vid_mode = GRUB_LINUX_VID_MODE_EXTENDED;
 	else if (grub_strcmp (val, "ask") == 0)
 	  vid_mode = GRUB_LINUX_VID_MODE_ASK;
 	else
 	  vid_mode = (grub_uint16_t) grub_strtoul (val, 0, 0);

 	if (grub_errno)
 	  goto fail;

 	lh.vid_mode = grub_cpu_to_le16 (vid_mode);
       }
     else 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;
 		/* Fallthrough.  */
 	      case 'm':
 		shift += 10;
 		/* Fallthrough.  */
 	      case 'k':
 		shift += 10;
 		/* Fallthrough.  */
 	      default:
 		break;
 	      }

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

   {
     grub_relocator_chunk_t ch;
     err = grub_relocator_alloc_chunk_addr (relocator, &ch,
 					   grub_linux_real_target,
 					   GRUB_LINUX_CL_OFFSET
 					   + maximal_cmdline_size);
     if (err)
       return err;
     grub_linux_real_chunk = get_virtual_current_address (ch);
   }

   /* Put the real mode code at the temporary address.  */
   grub_memmove (grub_linux_real_chunk, &lh, sizeof (lh));

   len = real_size + GRUB_DISK_SECTOR_SIZE - sizeof (lh);
   if (grub_file_read (file, grub_linux_real_chunk + sizeof (lh), len) != len)
     {
       if (!grub_errno)
 	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
 		    argv[0]);
       goto fail;
     }

   if (lh.header != grub_cpu_to_le32_compile_time (GRUB_LINUX_MAGIC_SIGNATURE)
       || grub_le_to_cpu16 (lh.version) < 0x0200)
     /* Clear the heap space.  */
     grub_memset (grub_linux_real_chunk
 		 + ((setup_sects + 1) << GRUB_DISK_SECTOR_BITS),
 		 0,
 		 ((GRUB_LINUX_MAX_SETUP_SECTS - setup_sects - 1)
 		  << GRUB_DISK_SECTOR_BITS));

   /* Create kernel command line.  */
   grub_memcpy ((char *)grub_linux_real_chunk + GRUB_LINUX_CL_OFFSET,
 		LINUX_IMAGE, sizeof (LINUX_IMAGE));
   err = grub_create_loader_cmdline (argc, argv,
 				    (char *)grub_linux_real_chunk
 				    + GRUB_LINUX_CL_OFFSET + sizeof (LINUX_IMAGE) - 1,
 				    maximal_cmdline_size
 				    - (sizeof (LINUX_IMAGE) - 1),
 				    GRUB_VERIFY_KERNEL_CMDLINE);
   if (err)
     goto fail;

   if (grub_linux_is_bzimage)
     grub_linux_prot_target = GRUB_LINUX_BZIMAGE_ADDR;
   else
     grub_linux_prot_target = GRUB_LINUX_ZIMAGE_ADDR;
   {
     grub_relocator_chunk_t ch;
     err = grub_relocator_alloc_chunk_addr (relocator, &ch,
 					   grub_linux_prot_target,
 					   grub_linux16_prot_size);
     if (err)
       return err;
     grub_linux_prot_chunk = get_virtual_current_address (ch);
   }

   len = grub_linux16_prot_size;
   if (grub_file_read (file, grub_linux_prot_chunk, grub_linux16_prot_size)
       != (grub_ssize_t) grub_linux16_prot_size && !grub_errno)
     grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
 		argv[0]);

   if (grub_errno == GRUB_ERR_NONE)
     {
       grub_loader_set (grub_linux16_boot, grub_linux_unload, 0);
       loaded = 1;
     }

  fail:

   if (file)
     grub_file_close (file);

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

   return grub_errno;
 }

 static grub_err_t
 grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
 		 int argc, char *argv[])
 {
   grub_size_t size = 0;
   grub_addr_t addr_max, addr_min;
   struct linux_kernel_header *lh;
   grub_uint8_t *initrd_chunk;
   grub_addr_t initrd_addr;
   grub_err_t err;
   struct grub_linux_initrd_context initrd_ctx = { 0, 0, 0 };

   if (argc == 0)
     {
       grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
       goto fail;
     }

   if (!loaded)
     {
       grub_error (GRUB_ERR_BAD_ARGUMENT, N_("you need to load the kernel first"));
       goto fail;
     }

   lh = (struct linux_kernel_header *) grub_linux_real_chunk;

   if (!(lh->header == grub_cpu_to_le32_compile_time (GRUB_LINUX_MAGIC_SIGNATURE)
 	&& grub_le_to_cpu16 (lh->version) >= 0x0200))
     {
       grub_error (GRUB_ERR_BAD_OS, "the kernel is too old for initrd");
       goto fail;
     }

   /* Get the highest address available for the initrd.  */
   if (grub_le_to_cpu16 (lh->version) >= 0x0203)
     {
       addr_max = grub_cpu_to_le32 (lh->initrd_addr_max);

       /* XXX in reality, Linux specifies a bogus value, so
 	 it is necessary to make sure that ADDR_MAX does not exceed
 	 0x3fffffff.  */
       if (addr_max > GRUB_LINUX_INITRD_MAX_ADDRESS)
 	addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;
     }
   else
     addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;

   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;

   addr_min = GRUB_LINUX_BZIMAGE_ADDR + grub_linux16_prot_size;

   if (grub_initrd_init (argc, argv, &initrd_ctx))
     goto fail;

   size = grub_get_initrd_size (&initrd_ctx);

   {
     grub_relocator_chunk_t ch;
     err = grub_relocator_alloc_chunk_align (relocator, &ch,
 					    addr_min, addr_max - size,
 					    size, 0x1000,
 					    GRUB_RELOCATOR_PREFERENCE_HIGH, 0);
     if (err)
       return err;
     initrd_chunk = get_virtual_current_address (ch);
     initrd_addr = get_physical_target_address (ch);
   }

   if (grub_initrd_load (&initrd_ctx, argv, initrd_chunk))
     goto fail;

   lh->ramdisk_image = initrd_addr;
   lh->ramdisk_size = size;

  fail:
   grub_initrd_close (&initrd_ctx);

   return grub_errno;
 }

 static grub_command_t cmd_linux, cmd_initrd;

 GRUB_MOD_INIT(linux16)
 {
   if (grub_efi_secure_boot())
     return;

   cmd_linux =
     grub_register_command ("linux16", grub_cmd_linux,
 			   0, N_("Load Linux."));
   cmd_initrd =
     grub_register_command ("initrd16", grub_cmd_initrd,
 			   0, N_("Load initrd."));
   my_mod = mod;
 }

 GRUB_MOD_FINI(linux16)
 {
   if (grub_efi_secure_boot())
     return;

   grub_unregister_command (cmd_linux);
   grub_unregister_command (cmd_initrd);
 }
	/* linux.c - boot Linux zImage or bzImage */
	/*
	* GRUB -- GRand Unified Bootloader
	* Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2007,2008,2009,2010 Free Software Foundation, Inc.
	*
	* GRUB 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, either version 3 of the License, or
	* (at your option) any later version.
	*
	* GRUB is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <grub/loader.h>
	#include <grub/file.h>
	#include <grub/err.h>
	#include <grub/device.h>
	#include <grub/disk.h>
	#include <grub/misc.h>
	#include <grub/types.h>
	#include <grub/memory.h>
	#include <grub/dl.h>
	#include <grub/cpu/linux.h>
	#include <grub/command.h>
	#include <grub/i18n.h>
	#include <grub/mm.h>
	#include <grub/cpu/relocator.h>
	#include <grub/video.h>
	#include <grub/i386/floppy.h>
	#include <grub/lib/cmdline.h>
	#include <grub/linux.h>
	#include <grub/efi/sb.h>

	GRUB_MOD_LICENSE ("GPLv3+");

	#define GRUB_LINUX_CL_OFFSET 0x9000

	static grub_dl_t my_mod;

	static grub_size_t linux_mem_size;
	static int loaded;
	static struct grub_relocator *relocator = NULL;
	static grub_addr_t grub_linux_real_target;
	static char *grub_linux_real_chunk;
	static grub_size_t grub_linux16_prot_size;
	static grub_size_t maximal_cmdline_size;

	static grub_err_t
	grub_linux16_boot (void)
	{
	grub_uint16_t segment;
	struct grub_relocator16_state state;

	segment = grub_linux_real_target >> 4;
	state.gs = state.fs = state.es = state.ds = state.ss = segment;
	state.sp = GRUB_LINUX_SETUP_STACK;
	state.cs = segment + 0x20;
	state.ip = 0;
	state.a20 = 1;

	grub_video_set_mode ("text", 0, 0);

	grub_stop_floppy ();

	return grub_relocator16_boot (relocator, state);
	}

	static grub_err_t
	grub_linux_unload (void)
	{
	grub_dl_unref (my_mod);
	loaded = 0;
	grub_relocator_unload (relocator);
	relocator = NULL;
	return GRUB_ERR_NONE;
	}

	static int
	target_hook (grub_uint64_t addr, grub_uint64_t size, grub_memory_type_t type,
	void *data)
	{
	grub_uint64_t *result = data;
	grub_uint64_t candidate;

	if (type != GRUB_MEMORY_AVAILABLE)
	return 0;
	if (addr >= 0xa0000)
	return 0;
	if (addr + size >= 0xa0000)
	size = 0xa0000 - addr;

	/* Put the real mode part at as a high location as possible. */
	candidate = addr + size - (GRUB_LINUX_CL_OFFSET + maximal_cmdline_size);
	/* But it must not exceed the traditional area. */
	if (candidate > GRUB_LINUX_OLD_REAL_MODE_ADDR)
	candidate = GRUB_LINUX_OLD_REAL_MODE_ADDR;
	if (candidate < addr)
	return 0;

	if (candidate > result \|\| result == (grub_uint64_t) -1)
	*result = candidate;
	return 0;
	}

	static grub_addr_t
	grub_find_real_target (void)
	{
	grub_uint64_t result = (grub_uint64_t) -1;

	grub_mmap_iterate (target_hook, &result);
	return result;
	}

	static grub_err_t
	grub_cmd_linux (grub_command_t cmd __attribute__ ((unused)),
	int argc, char *argv[])
	{
	grub_file_t file = 0;
	struct linux_kernel_header lh;
	grub_uint8_t setup_sects;
	grub_size_t real_size;
	grub_ssize_t len;
	int i;
	char *grub_linux_prot_chunk;
	int grub_linux_is_bzimage;
	grub_addr_t grub_linux_prot_target;
	grub_err_t err;

	grub_dl_ref (my_mod);

	if (argc == 0)
	{
	grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
	goto fail;
	}

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

	if (grub_file_read (file, &lh, sizeof (lh)) != sizeof (lh))
	{
	if (!grub_errno)
	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
	argv[0]);
	goto fail;
	}

	if (lh.boot_flag != grub_cpu_to_le16_compile_time (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;
	}

	grub_linux_is_bzimage = 0;
	setup_sects = lh.setup_sects;
	linux_mem_size = 0;

	maximal_cmdline_size = 256;

	if (lh.header == grub_cpu_to_le32_compile_time (GRUB_LINUX_MAGIC_SIGNATURE)
	&& grub_le_to_cpu16 (lh.version) >= 0x0200)
	{
	grub_linux_is_bzimage = (lh.loadflags & GRUB_LINUX_FLAG_BIG_KERNEL);
	lh.type_of_loader = GRUB_LINUX_BOOT_LOADER_TYPE;

	if (grub_le_to_cpu16 (lh.version) >= 0x0206)
	maximal_cmdline_size = grub_le_to_cpu32 (lh.cmdline_size) + 1;

	grub_linux_real_target = grub_find_real_target ();
	if (grub_linux_real_target == (grub_addr_t)-1)
	{
	grub_error (GRUB_ERR_OUT_OF_RANGE,
	"no appropriate low memory found");
	goto fail;
	}

	if (grub_le_to_cpu16 (lh.version) >= 0x0201)
	{
	lh.heap_end_ptr = grub_cpu_to_le16_compile_time (GRUB_LINUX_HEAP_END_OFFSET);
	lh.loadflags \|= GRUB_LINUX_FLAG_CAN_USE_HEAP;
	}

	if (grub_le_to_cpu16 (lh.version) >= 0x0202)
	lh.cmd_line_ptr = grub_linux_real_target + GRUB_LINUX_CL_OFFSET;
	else
	{
	lh.cl_magic = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_MAGIC);
	lh.cl_offset = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_OFFSET);
	lh.setup_move_size = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_OFFSET
	+ maximal_cmdline_size);
	}
	}
	else
	{
	/* Your kernel is quite old... */
	lh.cl_magic = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_MAGIC);
	lh.cl_offset = grub_cpu_to_le16_compile_time (GRUB_LINUX_CL_OFFSET);

	setup_sects = GRUB_LINUX_DEFAULT_SETUP_SECTS;

	grub_linux_real_target = GRUB_LINUX_OLD_REAL_MODE_ADDR;
	}

	/* 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;
	grub_linux16_prot_size = grub_file_size (file)
	- real_size - GRUB_DISK_SECTOR_SIZE;

	if (! grub_linux_is_bzimage
	&& GRUB_LINUX_ZIMAGE_ADDR + grub_linux16_prot_size
	> grub_linux_real_target)
	{
	grub_error (GRUB_ERR_BAD_OS, "too big zImage (0x%x > 0x%x), use bzImage instead",
	(char *) GRUB_LINUX_ZIMAGE_ADDR + grub_linux16_prot_size,
	(grub_size_t) grub_linux_real_target);
	goto fail;
	}

	grub_dprintf ("linux", "[Linux-%s, setup=0x%x, size=0x%x]\n",
	grub_linux_is_bzimage ? "bzImage" : "zImage",
	(unsigned) real_size,
	(unsigned) grub_linux16_prot_size);

	relocator = grub_relocator_new ();
	if (!relocator)
	goto fail;

	for (i = 1; i < argc; i++)
	if (grub_memcmp (argv[i], "vga=", 4) == 0)
	{
	/* Video mode selection support. */
	grub_uint16_t vid_mode;
	char *val = argv[i] + 4;

	if (grub_strcmp (val, "normal") == 0)
	vid_mode = GRUB_LINUX_VID_MODE_NORMAL;
	else if (grub_strcmp (val, "ext") == 0)
	vid_mode = GRUB_LINUX_VID_MODE_EXTENDED;
	else if (grub_strcmp (val, "ask") == 0)
	vid_mode = GRUB_LINUX_VID_MODE_ASK;
	else
	vid_mode = (grub_uint16_t) grub_strtoul (val, 0, 0);

	if (grub_errno)
	goto fail;

	lh.vid_mode = grub_cpu_to_le16 (vid_mode);
	}
	else 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;
	/* Fallthrough. */
	case 'm':
	shift += 10;
	/* Fallthrough. */
	case 'k':
	shift += 10;
	/* Fallthrough. */
	default:
	break;
	}

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

	{
	grub_relocator_chunk_t ch;
	err = grub_relocator_alloc_chunk_addr (relocator, &ch,
	grub_linux_real_target,
	GRUB_LINUX_CL_OFFSET
	+ maximal_cmdline_size);
	if (err)
	return err;
	grub_linux_real_chunk = get_virtual_current_address (ch);
	}

	/* Put the real mode code at the temporary address. */
	grub_memmove (grub_linux_real_chunk, &lh, sizeof (lh));

	len = real_size + GRUB_DISK_SECTOR_SIZE - sizeof (lh);
	if (grub_file_read (file, grub_linux_real_chunk + sizeof (lh), len) != len)
	{
	if (!grub_errno)
	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
	argv[0]);
	goto fail;
	}

	if (lh.header != grub_cpu_to_le32_compile_time (GRUB_LINUX_MAGIC_SIGNATURE)
	\|\| grub_le_to_cpu16 (lh.version) < 0x0200)
	/* Clear the heap space. */
	grub_memset (grub_linux_real_chunk
	+ ((setup_sects + 1) << GRUB_DISK_SECTOR_BITS),
	0,
	((GRUB_LINUX_MAX_SETUP_SECTS - setup_sects - 1)
	<< GRUB_DISK_SECTOR_BITS));

	/* Create kernel command line. */
	grub_memcpy ((char *)grub_linux_real_chunk + GRUB_LINUX_CL_OFFSET,
	LINUX_IMAGE, sizeof (LINUX_IMAGE));
	err = grub_create_loader_cmdline (argc, argv,
	(char *)grub_linux_real_chunk
	+ GRUB_LINUX_CL_OFFSET + sizeof (LINUX_IMAGE) - 1,
	maximal_cmdline_size
	- (sizeof (LINUX_IMAGE) - 1),
	GRUB_VERIFY_KERNEL_CMDLINE);
	if (err)
	goto fail;

	if (grub_linux_is_bzimage)
	grub_linux_prot_target = GRUB_LINUX_BZIMAGE_ADDR;
	else
	grub_linux_prot_target = GRUB_LINUX_ZIMAGE_ADDR;
	{
	grub_relocator_chunk_t ch;
	err = grub_relocator_alloc_chunk_addr (relocator, &ch,
	grub_linux_prot_target,
	grub_linux16_prot_size);
	if (err)
	return err;
	grub_linux_prot_chunk = get_virtual_current_address (ch);
	}

	len = grub_linux16_prot_size;
	if (grub_file_read (file, grub_linux_prot_chunk, grub_linux16_prot_size)
	!= (grub_ssize_t) grub_linux16_prot_size && !grub_errno)
	grub_error (GRUB_ERR_BAD_OS, N_("premature end of file %s"),
	argv[0]);

	if (grub_errno == GRUB_ERR_NONE)
	{
	grub_loader_set (grub_linux16_boot, grub_linux_unload, 0);
	loaded = 1;
	}

	fail:

	if (file)
	grub_file_close (file);

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

	return grub_errno;
	}

	static grub_err_t
	grub_cmd_initrd (grub_command_t cmd __attribute__ ((unused)),
	int argc, char *argv[])
	{
	grub_size_t size = 0;
	grub_addr_t addr_max, addr_min;
	struct linux_kernel_header *lh;
	grub_uint8_t *initrd_chunk;
	grub_addr_t initrd_addr;
	grub_err_t err;
	struct grub_linux_initrd_context initrd_ctx = { 0, 0, 0 };

	if (argc == 0)
	{
	grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
	goto fail;
	}

	if (!loaded)
	{
	grub_error (GRUB_ERR_BAD_ARGUMENT, N_("you need to load the kernel first"));
	goto fail;
	}

	lh = (struct linux_kernel_header *) grub_linux_real_chunk;

	if (!(lh->header == grub_cpu_to_le32_compile_time (GRUB_LINUX_MAGIC_SIGNATURE)
	&& grub_le_to_cpu16 (lh->version) >= 0x0200))
	{
	grub_error (GRUB_ERR_BAD_OS, "the kernel is too old for initrd");
	goto fail;
	}

	/* Get the highest address available for the initrd. */
	if (grub_le_to_cpu16 (lh->version) >= 0x0203)
	{
	addr_max = grub_cpu_to_le32 (lh->initrd_addr_max);

	/* XXX in reality, Linux specifies a bogus value, so
	it is necessary to make sure that ADDR_MAX does not exceed
	0x3fffffff. */
	if (addr_max > GRUB_LINUX_INITRD_MAX_ADDRESS)
	addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;
	}
	else
	addr_max = GRUB_LINUX_INITRD_MAX_ADDRESS;

	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;

	addr_min = GRUB_LINUX_BZIMAGE_ADDR + grub_linux16_prot_size;

	if (grub_initrd_init (argc, argv, &initrd_ctx))
	goto fail;

	size = grub_get_initrd_size (&initrd_ctx);

	{
	grub_relocator_chunk_t ch;
	err = grub_relocator_alloc_chunk_align (relocator, &ch,
	addr_min, addr_max - size,
	size, 0x1000,
	GRUB_RELOCATOR_PREFERENCE_HIGH, 0);
	if (err)
	return err;
	initrd_chunk = get_virtual_current_address (ch);
	initrd_addr = get_physical_target_address (ch);
	}

	if (grub_initrd_load (&initrd_ctx, argv, initrd_chunk))
	goto fail;

	lh->ramdisk_image = initrd_addr;
	lh->ramdisk_size = size;

	fail:
	grub_initrd_close (&initrd_ctx);

	return grub_errno;
	}

	static grub_command_t cmd_linux, cmd_initrd;

	GRUB_MOD_INIT(linux16)
	{
	if (grub_efi_secure_boot())
	return;

	cmd_linux =
	grub_register_command ("linux16", grub_cmd_linux,
	0, N_("Load Linux."));
	cmd_initrd =
	grub_register_command ("initrd16", grub_cmd_initrd,
	0, N_("Load initrd."));
	my_mod = mod;
	}

	GRUB_MOD_FINI(linux16)
	{
	if (grub_efi_secure_boot())
	return;

	grub_unregister_command (cmd_linux);
	grub_unregister_command (cmd_initrd);
	}