File force-LBA-off.diff of Package grub
Index: grub-0.97/docs/grub.texi
===================================================================
--- grub-0.97.orig/docs/grub.texi
+++ grub-0.97/docs/grub.texi
@@ -2919,7 +2919,7 @@ appropriate parameters in the Linux setu
@node install
@subsection install
-@deffn Command install [@option{--force-lba}] [@option{--stage2=os_stage2_file}] stage1_file [@option{d}] dest_dev stage2_file [addr] [@option{p}] [config_file] [real_config_file]
+@deffn Command install [@option{--force-lba[=off]}] [@option{--stage2=os_stage2_file}] stage1_file [@option{d}] dest_dev stage2_file [addr] [@option{p}] [config_file] [real_config_file]
This command is fairly complex, and you should not use this command
unless you are familiar with GRUB. Use @command{setup} (@pxref{setup})
instead.
@@ -2966,6 +2966,13 @@ HP Vectra XU 6/200 BIOS version GG.06.11
bitmap even if they do have the support. So GRUB provides a solution to
ignore the wrong bitmap, that is, the option @option{--force-lba}. Don't
use this option if you know that your BIOS doesn't have LBA support.
+On the other hand there is at least one known BIOS that does the opposite,
+it claims to support LBA and then fails to provide it. Iff you have an
+Adaptec 2940 with BIOS revision 1.21 ( newer ones just work and older ones
+don't make the false claim ), or otherwise experience grub hanging
+after stage1, you can try to use the option @option{--force-lba=off},
+as long as all disk blocks involved in booting reside
+within the first 1024 cylinders.
@strong{Caution3:} You must specify the option @option{--stage2} in the
grub shell, if you cannot unmount the filesystem where your stage2 file
Index: grub-0.97/stage1/stage1.S
===================================================================
--- grub-0.97.orig/stage1/stage1.S
+++ grub-0.97/stage1/stage1.S
@@ -177,7 +177,11 @@ real_start:
/* check if AH=0x42 is supported if FORCE_LBA is zero */
MOV_MEM_TO_AL(ABS(force_lba)) /* movb ABS(force_lba), %al */
testb %al, %al
+ /* check if LBA is forced OFF 0x80 <= %al <= 0xff */
+ js chs_mode
+ /* or forced ON 0x01 <= %al <= 0x7f */
jnz lba_mode
+ /* otherwise trust BIOS int's result */
andw $1, %cx
jz chs_mode
Index: grub-0.97/stage2/asm.S
===================================================================
--- grub-0.97.orig/stage2/asm.S
+++ grub-0.97/stage2/asm.S
@@ -1091,7 +1091,11 @@ ENTRY(check_int13_extensions)
/* check if AH=0x42 is supported if FORCE_LBA is zero */
movb EXT_C(force_lba), %al
testb %al, %al
+ /* check if LBA is forced OFF 0x80 <= %al <= 0xff */
+ js 1f
+ /* or forced ON 0x01 <= %al <= 0x7f */
jnz 2f
+ /* otherwise trust BIOS int's result */
andw $1, %cx
jnz 2f
Index: grub-0.97/stage2/builtins.c
===================================================================
--- grub-0.97.orig/stage2/builtins.c
+++ grub-0.97/stage2/builtins.c
@@ -1876,7 +1876,12 @@ install_func (char *arg, int flags)
/* First, check the GNU-style long option. */
while (1)
{
- if (grub_memcmp ("--force-lba", arg, sizeof ("--force-lba") - 1) == 0)
+ if (grub_memcmp ("--force-lba=off", arg, sizeof ("--force-lba=off") - 1) == 0)
+ {
+ is_force_lba = 0xff;
+ arg = skip_to (0, arg);
+ }
+ else if (grub_memcmp ("--force-lba", arg, sizeof ("--force-lba") - 1) == 0)
{
is_force_lba = 1;
arg = skip_to (0, arg);
@@ -2319,7 +2324,7 @@ static struct builtin builtin_install =
"install",
install_func,
BUILTIN_CMDLINE,
- "install [--stage2=STAGE2_FILE] [--force-lba] STAGE1 [d] DEVICE STAGE2 [ADDR] [p] [CONFIG_FILE] [REAL_CONFIG_FILE]",
+ "install [--stage2=STAGE2_FILE] [--force-lba[=off]] STAGE1 [d] DEVICE STAGE2 [ADDR] [p] [CONFIG_FILE] [REAL_CONFIG_FILE]",
"Install STAGE1 on DEVICE, and install a blocklist for loading STAGE2"
" as a Stage 2. If the option `d' is present, the Stage 1 will always"
" look for the disk where STAGE2 was installed, rather than using"
@@ -2332,8 +2337,9 @@ static struct builtin builtin_install =
" 1.5 and REAL_CONFIG_FILE is present, then the Stage 2 CONFIG_FILE is"
" patched with the configuration filename REAL_CONFIG_FILE."
" If the option `--force-lba' is specified, disable some sanity checks"
- " for LBA mode. If the option `--stage2' is specified, rewrite the Stage"
- " 2 via your OS's filesystem instead of the raw device."
+ " for LBA mode, `--force-lba=off' will disable it completely. If the"
+ " option `--stage2' is specified, rewrite the Stage 2 via your OS's"
+ " filesystem instead of the raw device."
};
@@ -3946,7 +3952,12 @@ setup_func (char *arg, int flags)
/* Check if the user specifies --force-lba. */
while (1)
{
- if (grub_memcmp ("--force-lba", arg, sizeof ("--force-lba") - 1) == 0)
+ if (grub_memcmp ("--force-lba=off", arg, sizeof ("--force-lba=off") - 1) == 0)
+ {
+ is_force_lba = 0xff;
+ arg = skip_to (0, arg);
+ }
+ else if (grub_memcmp ("--force-lba", arg, sizeof ("--force-lba") - 1) == 0)
{
is_force_lba = 1;
arg = skip_to (0, arg);
@@ -4077,7 +4088,9 @@ setup_func (char *arg, int flags)
#if 1
/* Don't embed a drive number unnecessarily. */
grub_sprintf (cmd_arg, "%s%s%s%s %s%s %s p %s %s",
- is_force_lba? "--force-lba " : "",
+ is_force_lba ?
+ (is_force_lba == 0xff ? "--force-lba=off " : "--force-lba ")
+ : "",
stage2_arg? stage2_arg : "",
stage2_arg? " " : "",
stage1,
@@ -4130,17 +4143,18 @@ static struct builtin builtin_setup =
"setup",
setup_func,
BUILTIN_CMDLINE | BUILTIN_HELP_LIST,
- "setup [--prefix=DIR] [--stage2=STAGE2_FILE] [--force-lba] INSTALL_DEVICE [IMAGE_DEVICE]",
+ "setup [--prefix=DIR] [--stage2=STAGE2_FILE] [--force-lba[=off]] INSTALL_DEVICE [IMAGE_DEVICE]",
"Set up the installation of GRUB automatically. This command uses"
" the more flexible command \"install\" in the backend and installs"
" GRUB into the device INSTALL_DEVICE. If IMAGE_DEVICE is specified,"
" then find the GRUB images in the device IMAGE_DEVICE, otherwise"
" use the current \"root device\", which can be set by the command"
" \"root\". If you know that your BIOS should support LBA but GRUB"
- " doesn't work in LBA mode, specify the option `--force-lba'."
- " If you install GRUB under the grub shell and you cannot unmount the"
- " partition where GRUB images reside, specify the option `--stage2'"
- " to tell GRUB the file name under your OS."
+ " doesn't work in LBA mode, specify the option `--force-lba'. If the"
+ " BIOS claims to support LBA mode but really doesn't, use"
+ " `--force-lba=off'. If you install GRUB under the grub shell and"
+ " you cannot unmount the partition where GRUB images reside, specify"
+ " the option `--stage2' to tell GRUB the file name under your OS."
};
