I attach the patch that makes grub2 to have a map command.
The map command only modifies a vector. If we want true map in grub2 we
need to hook some functions so that some bios calls ocurr.

Meanwhile I think how to do it... here there is my patch and some
questions and suggestions.


> diff -urN grub2_2007_05_31_original/commands/i386/pc/map.c grub2_2007_05_31_map/commands/i386/pc/map.c
> --- grub2_2007_05_31_original/commands/i386/pc/map.c	1970-01-01 01:00:00.000000000 +0100
> +++ grub2_2007_05_31_map/commands/i386/pc/map.c	2007-06-17 05:40:39.000000000 +0200
> @@ -0,0 +1,108 @@
> +/* map.c - Define map array  */
> +
> +#include <grub/normal.h>
> +#include <grub/dl.h>
> +#include <grub/arg.h>
> +#include <grub/disk.h>
> +#include <grub/term.h>
> +#include <grub/misc.h>
> +#include <grub/device.h>
> +#include <grub/file.h>
I am including file.h because it includes the function:
grub_file_get_device_name
I think an equivalent function such as:
grub_disk_get_device_name
should be defined in disk.h and implemented where it corresponds to be
implemented.
> +
> +/* The size of the drive map.  */
> +#define DRIVE_MAP_SIZE		16
Is there any bios that supports more than 16 hard disks?
> +/* The BIOS drive map.  */
> +static unsigned short bios_drive_map[DRIVE_MAP_SIZE + 1];
> +
> +int real_map_func (unsigned long to, unsigned long from) {
> +int i;
> +  /* Search for an empty slot in BIOS_DRIVE_MAP.  */
> +  for (i = 0; i < DRIVE_MAP_SIZE; i++)
> +    {
> +      /* Perhaps the user wants to override the map.  */
> +      if ((bios_drive_map[i] & 0xff) == from)
> +	break;
> +      
> +      if (! bios_drive_map[i])
> +	break;
> +    }
> +
> +  if (i == DRIVE_MAP_SIZE)
> +    {
> +      return GRUB_ERR_OUT_OF_RANGE;
> +    }
> +
> +  if (to == from)
> +    /* If TO is equal to FROM, delete the entry.  */
> +    grub_memmove ((char *) &bios_drive_map[i], (char *) &bios_drive_map[i + 1],
> +		  sizeof (unsigned short) * (DRIVE_MAP_SIZE - i));
> +  else
> +    bios_drive_map[i] = from | (to << 8);
> +  
> +  return 0;
> +
> +
> +}
The above code was copy-pasted from grub legacy. Do you think it can be
improved?
> +
> +
> +
> +static grub_err_t
> +grub_cmd_map (struct grub_arg_list *state __attribute__ ((unused)),
> +	       int argc, char **args)
> +{
> +  grub_disk_t map_disk_to,map_disk_from;
> +
> +/* TODO: Check map arguments from grub2 engine */  
> +  if (argc != 2)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT, "Two devices required");
> +  map_disk_to = grub_disk_open (grub_file_get_device_name(args[0]));
> +  if (! map_disk_to)
> +    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "Unknown TO disk");
> +/* This was a marco_g suggestion but it does not make sense to me.
> +  if (grub_strcmp(map_disk_to->name,"biosdisk"))
> +    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "TO disk is not a bios disk.");
> +*/
marco_g ... if I try to grub_printf the disk_to-> name it says hd0. It
does not say "biosdisk" as you have told me.
I am bit confused.
> +  map_disk_from = grub_disk_open (grub_file_get_device_name(args[1]));
> +  if (! map_disk_from)
> +    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "Unknown FROM disk");
> +/* This was a marco_g suggestion but it does not make sense to me.
> +  if (grub_strcmp(map_disk_from->name,"biosdisk"))
> +    return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "FROM disk is not a bios disk.");
> +*/
Idem for marco_g.

Should I add a function that checks the validity of a hard disk and
asignts it to a grub_disk_t variable and call it twice in order to make
the code smaller ?
> +
> +
> +  return (real_map_func(map_disk_to->id,map_disk_from->id));
> +  
> +}
> +
> +
> +GRUB_MOD_INIT(map)
> +{
> +  (void)mod;			/* To stop warning. */
> +  grub_register_command ("map", grub_cmd_map, GRUB_COMMAND_FLAG_BOTH,
> +			 "map TODEVICE FROMDEVICE", "Map a drive to another", 0);
> +}
> +
> +GRUB_MOD_FINI(map)
> +{
> +  grub_unregister_command ("map");
> +}
> diff -urN grub2_2007_05_31_original/conf/i386-pc.rmk grub2_2007_05_31_map/conf/i386-pc.rmk
> --- grub2_2007_05_31_original/conf/i386-pc.rmk	2007-06-11 11:53:27.000000000 +0200
> +++ grub2_2007_05_31_map/conf/i386-pc.rmk	2007-06-14 12:38:00.000000000 +0200
> @@ -1,5 +1,7 @@
>  # -*- makefile -*-
>  
> +
> +
>  COMMON_ASFLAGS = -nostdinc -fno-builtin -m32
>  COMMON_CFLAGS = -fno-builtin -mrtd -mregparm=3 -m32
>  COMMON_LDFLAGS = -m32 -nostdlib
> @@ -121,7 +123,7 @@
>  pkgdata_MODULES = _chain.mod _linux.mod linux.mod normal.mod \
>  	_multiboot.mod chain.mod multiboot.mod reboot.mod halt.mod	\
>  	vbe.mod vbetest.mod vbeinfo.mod video.mod gfxterm.mod \
> -	videotest.mod play.mod bitmap.mod tga.mod cpuid.mod
> +	videotest.mod map.mod play.mod bitmap.mod tga.mod cpuid.mod
>  
>  # For _chain.mod.
>  _chain_mod_SOURCES = loader/i386/pc/chainloader.c
> @@ -195,6 +197,11 @@
>  vbetest_mod_CFLAGS = $(COMMON_CFLAGS)
>  vbetest_mod_LDFLAGS = $(COMMON_LDFLAGS)
>  
> +# For map.mod.
> +map_mod_SOURCES = commands/i386/pc/map.c
> +map_mod_CFLAGS = $(COMMON_CFLAGS)
> +map_mod_LDFLAGS = $(COMMON_LDFLAGS)
> +
>  # For play.mod.
>  play_mod_SOURCES = commands/i386/pc/play.c
>  play_mod_CFLAGS = $(COMMON_CFLAGS)

Is it important that I also copy-paste the rmk files modifications or not?

adrian15