Re: [PATCH v0] Support to disable reed-solomon codes

[Andrey Borzenkov <arvidjaar@gmail.com>]

В Fri,  1 Nov 2013 17:04:00 -0700
Jon McCune <jonmccune@google.com> пишет:

>  * new grub-*-setup flag to disable insertion of reed solomon codes
>  * grub-install support for option --no-rs-codes
> 

What problem does it solve?

> Signed-off-by: Jon McCune <jonmccune@google.com>
> ---
>  include/grub/util/install.h |  4 ++--
>  util/grub-install.in        |  7 ++++++-
>  util/grub-setup.c           | 12 +++++++++++-
>  util/setup.c                | 48 +++++++++++++++++++++++----------------------
>  4 files changed, 44 insertions(+), 27 deletions(-)
> 
> diff --git a/include/grub/util/install.h b/include/grub/util/install.h
> index 7eb6141..9b33368 100644
> --- a/include/grub/util/install.h
> +++ b/include/grub/util/install.h
> @@ -53,12 +53,12 @@ void
>  grub_util_bios_setup (const char *dir,
>  		      const char *boot_file, const char *core_file,
>  		      const char *dest, int force,
> -		      int fs_probe, int allow_floppy);
> +		      int fs_probe, int allow_floppy, int no_rs_codes);
>  void
>  grub_util_sparc_setup (const char *dir,
>  		       const char *boot_file, const char *core_file,
>  		       const char *dest, int force,
> -		       int fs_probe, int allow_floppy);
> +		       int fs_probe, int allow_floppy, int no_rs_codes);
>  
>  char *
>  grub_install_get_image_targets_string (void);
> diff --git a/util/grub-install.in b/util/grub-install.in
> index 7cd089b..79d103f 100644
> --- a/util/grub-install.in
> +++ b/util/grub-install.in
> @@ -87,6 +87,7 @@ usage () {
>      print_option_help  "--removable" "$(gettext "the installation device is removable. This option is only available on EFI.")"
>      print_option_help  "--bootloader-id=$(gettext "ID")" "$(gettext "the ID of bootloader. This option is only available on EFI.")"
>      print_option_help "--efi-directory=$(gettext "DIR")" "$(gettext "use DIR as the EFI System Partition root.")"
> +    print_option_help "--no-rs-codes" "$(gettext "Do not apply any reed-solomon codes, even if there is enough space.")"
>  echo
>  gettext "INSTALL_DEVICE must be system device filename.";echo
>  echo
> @@ -100,6 +101,7 @@ gettext "Report bugs to <bug-grub@gnu.org>."; echo
>  allow_floppy=""
>  force_file_id=
>  efidir=
> +no_rs_codes=""
>  
>  # Check the arguments.
>  while test $# -gt 0
> @@ -199,6 +201,9 @@ do
>      --no-nvram)
>  	update_nvram=no ;;
>  
> +    --no-rs-codes)
> +	no_rs_codes="--no-rs-codes" ;;
> +
>      # This is an undocumented feature...
>      --debug)
>  	debug=yes ;;
> @@ -680,7 +685,7 @@ fi
>  # Perform the grub_modinfo_platform-dependent install
>  if [ "${grub_modinfo_target_cpu}-${grub_modinfo_platform}" = "i386-pc" ] || [ "${grub_modinfo_target_cpu}-${grub_modinfo_platform}" = "sparc64-ieee1275" ] ; then
>      # Now perform the installation.
> -    "$grub_setup" ${allow_floppy} ${setup_verbose} ${setup_force} --directory="${grubdir}/${grub_modinfo_target_cpu}-$grub_modinfo_platform" \
> +    "$grub_setup" ${allow_floppy} ${setup_verbose} ${setup_force} ${no_rs_codes} --directory="${grubdir}/${grub_modinfo_target_cpu}-$grub_modinfo_platform" \
>  	--device-map="${device_map}" "${install_device}" || exit 1
>  elif [ "${grub_modinfo_target_cpu}-${grub_modinfo_platform}" = "i386-ieee1275" ] || [ "${grub_modinfo_target_cpu}-${grub_modinfo_platform}" = "powerpc-ieee1275" ]; then
>  
> diff --git a/util/grub-setup.c b/util/grub-setup.c
> index 90b9de0..088efcf 100644
> --- a/util/grub-setup.c
> +++ b/util/grub-setup.c
> @@ -83,6 +83,10 @@ static struct argp_option options[] = {
>        likely to make the install unbootable from HDD.  */
>     N_("make the drive also bootable as floppy (default for fdX devices). May break on some BIOSes."), 0},
>  
> +  {"no-rs-codes", 'n', 0,      0,
> +   N_("Do not apply any reed-solomon codes, even if there is enough space."), 0},
> +
> +
>    { 0, 0, 0, 0, 0, 0 }
>  };
>  
> @@ -118,6 +122,7 @@ struct arguments
>    int  fs_probe;
>    int allow_floppy;
>    char *device;
> +  int no_rs_codes;
>  };
>  
>  static error_t
> @@ -173,6 +178,10 @@ argp_parser (int key, char *arg, struct argp_state *state)
>          verbosity++;
>          break;
>  
> +      case 'n':
> +        arguments->no_rs_codes = 1;
> +        break;
> +
>        case ARGP_KEY_ARG:
>          if (state->arg_num == 0)
>            arguments->device = xstrdup(arg);
> @@ -292,7 +301,8 @@ main (int argc, char *argv[])
>  		   arguments.boot_file ? : DEFAULT_BOOT_FILE,
>  		   arguments.core_file ? : DEFAULT_CORE_FILE,
>  		   dest_dev, arguments.force,
> -		   arguments.fs_probe, arguments.allow_floppy);
> +		   arguments.fs_probe, arguments.allow_floppy,
> +		   arguments.no_rs_codes);
>  
>    /* Free resources.  */
>    grub_fini_all ();
> diff --git a/util/setup.c b/util/setup.c
> index 5b7c384..95f173e 100644
> --- a/util/setup.c
> +++ b/util/setup.c
> @@ -241,7 +241,7 @@ void
>  SETUP (const char *dir,
>         const char *boot_file, const char *core_file,
>         const char *dest, int force,
> -       int fs_probe, int allow_floppy)
> +       int fs_probe, int allow_floppy, int no_rs_codes)
>  {
>    char *core_path;
>    char *boot_img, *core_img, *boot_path;
> @@ -540,27 +540,29 @@ SETUP (const char *dir,
>      bl.first_block = (struct grub_boot_blocklist *) (core_img
>  						     + GRUB_DISK_SECTOR_SIZE
>  						     - sizeof (*bl.block));
> -
> -    grub_size_t no_rs_length;
> -    grub_set_unaligned32 ((core_img + GRUB_DISK_SECTOR_SIZE
> -			   + GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY),
> -			  grub_host_to_target32 (nsec * GRUB_DISK_SECTOR_SIZE - core_size));
> -    no_rs_length = grub_target_to_host16 
> -      (grub_get_unaligned16 (core_img
> -			     + GRUB_DISK_SECTOR_SIZE
> -			     + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH));
> -
> -    if (no_rs_length == 0xffff)
> -      grub_util_error ("%s", _("core.img version mismatch"));
> -
> -    void *tmp = xmalloc (core_size);
> -    grub_memcpy (tmp, core_img, core_size);
> -    grub_reed_solomon_add_redundancy (core_img + no_rs_length + GRUB_DISK_SECTOR_SIZE,
> -				      core_size - no_rs_length - GRUB_DISK_SECTOR_SIZE,
> -				      nsec * GRUB_DISK_SECTOR_SIZE
> -				      - core_size);
> -    assert (grub_memcmp (tmp, core_img, core_size) == 0);
> -    free (tmp);
> +    if (!no_rs_codes)
> +      {
> +        grub_size_t no_rs_length;
> +        grub_set_unaligned32 ((core_img + GRUB_DISK_SECTOR_SIZE
> +                               + GRUB_KERNEL_I386_PC_REED_SOLOMON_REDUNDANCY),
> +                              grub_host_to_target32 (nsec * GRUB_DISK_SECTOR_SIZE - core_size));
> +        no_rs_length = grub_target_to_host16
> +            (grub_get_unaligned16 (core_img
> +                                   + GRUB_DISK_SECTOR_SIZE
> +                                   + GRUB_KERNEL_I386_PC_NO_REED_SOLOMON_LENGTH));
> +
> +        if (no_rs_length == 0xffff)
> +          grub_util_error ("%s", _("core.img version mismatch"));
> +
> +        void *tmp = xmalloc (core_size);
> +        grub_memcpy (tmp, core_img, core_size);
> +        grub_reed_solomon_add_redundancy (core_img + no_rs_length + GRUB_DISK_SECTOR_SIZE,
> +                                          core_size - no_rs_length - GRUB_DISK_SECTOR_SIZE,
> +                                          nsec * GRUB_DISK_SECTOR_SIZE
> +                                          - core_size);
> +        assert (grub_memcmp (tmp, core_img, core_size) == 0);
> +        free (tmp);
> +      }
>  
>      /* Write the core image onto the disk.  */
>      for (i = 0; i < nsec; i++)
> @@ -574,7 +576,7 @@ SETUP (const char *dir,
>    }
>  
>  unable_to_embed:
> -#endif
> +#endif  /* ifdef GRUB_SETUP_BIOS */
>  
>    if (dest_dev->disk->dev->id != root_dev->disk->dev->id)
>      grub_util_error ("%s", _("embedding is not possible, but this is required for "