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2005-02-15 Yoshinori K. Okuji <okuji@enbug.org>

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* stage2/builtins.c (install_func): If DEST_DRIVE is a hard
  disk, enable the workaround in Stage 1 by replacing the jmp
  with double nop's.

  * stage1/stage1.h (STAGE1_BOOT_DRIVE_CHECK): New macro.
  (STAGE1_BOOT_DRIVE_MASK): Removed.

  * stage1/stage1.S (boot_drive_check): New label. This implements
  a different workaround for buggy BIOSes which don't pass boot
  drive correctly. This is effective for BIOSes which pass a value
  without the seventh bit (0x80).
  (boot_drive_mask): Removed.
This commit is contained in:
okuji 2005-02-15 22:05:07 +00:00
parent fb908db4ad
commit 041e243877
5 changed files with 41 additions and 12 deletions
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15
ChangeLog
View file

@ -1,3 +1,18 @@
2005-02-15 Yoshinori K. Okuji <okuji@enbug.org>
* stage2/builtins.c (install_func): If DEST_DRIVE is a hard
disk, enable the workaround in Stage 1 by replacing the jmp
with double nop's.
* stage1/stage1.h (STAGE1_BOOT_DRIVE_CHECK): New macro.
(STAGE1_BOOT_DRIVE_MASK): Removed.
* stage1/stage1.S (boot_drive_check): New label. This implements
a different workaround for buggy BIOSes which don't pass boot
drive correctly. This is effective for BIOSes which pass a value
without the seventh bit (0x80).
(boot_drive_mask): Removed.
2005-02-03 Yoshinori K. Okuji <okuji@enbug.org>
* grub/asmstub.c (console_current_color): Make it global as

6
NEWS
View file

@ -1,5 +1,11 @@
NEWS - list of user-visible changes between releases of GRUB
New:
* Fix the prototypes and the definitions of nested functions. This was
required for gcc-4.
* Implement a more robust workaround for buggy BIOSes which don't pass
boot drive correctly (notably for HP Vectra).
New in 0.96 - 2005-01-30:
* The command "fallback" supports mutiple fallback entries.
* The command "savedefault" supports an optional argument which

16
stage1/stage1.S
View file

@ -108,12 +108,18 @@ after_BPB:
/*
* This is a workaround for buggy BIOSes which don't pass boot
* drive correctly. If GRUB is installed into a HDD, do
* "orb $0x80, %dl", otherwise "orb $0x00, %dl" (i.e. nop).
* drive correctly. If GRUB is installed into a HDD, check if
* DL is masked correctly. If not, assume that the BIOS passed
* a bogus value and set DL to 0x80, since this is the only
* possible boot drive. If GRUB is installed into a floppy,
* this does nothing (only jump).
*/
.byte 0x80, 0xca
boot_drive_mask:
.byte 0x00
boot_drive_check:
jmp 1f
testb $0x80, %dl
jnz 1f
movb $0x80, %dl
1:
/*
* ljmp to the next instruction because some bogus BIOSes

4
stage1/stage1.h
View file

@ -51,8 +51,8 @@
/* The offset of STAGE2_SEGMENT. */
#define STAGE1_STAGE2_SEGMENT 0x48
/* The offset of BOOT_DRIVE_MASK. */
#define STAGE1_BOOT_DRIVE_MASK 0x4d
/* The offset of BOOT_DRIVE_CHECK. */
#define STAGE1_BOOT_DRIVE_CHECK 0x4b
/* The offset of a magic number used by Windows NT. */
#define STAGE1_WINDOWS_NT_MAGIC 0x1b8

12
stage2/builtins.c
View file

@ -1952,11 +1952,13 @@ install_func (char *arg, int flags)
/* Set the "force LBA" flag. */
*((unsigned char *) (stage1_buffer + STAGE1_FORCE_LBA)) = is_force_lba;
/* Set the boot drive mask. This is a workaround for buggy BIOSes which
don't pass boot drive correctly. Instead, they pass 0x00 even when
booted from 0x80. */
*((unsigned char *) (stage1_buffer + STAGE1_BOOT_DRIVE_MASK))
= (dest_drive & BIOS_FLAG_FIXED_DISK);
/* If DEST_DRIVE is a hard disk, enable the workaround, which is
for buggy BIOSes which don't pass boot drive correctly. Instead,
they pass 0x00 or 0x01 even when booted from 0x80. */
if (dest_drive & BIOS_FLAG_FIXED_DISK)
/* Replace the jmp (2 bytes) with double nop's. */
*((unsigned short *) (stage1_buffer + STAGE1_BOOT_DRIVE_CHECK))
= 0x9090;
/* Read the first sector of Stage 2. */
disk_read_hook = disk_read_savesect_func;