vbatts/grub
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2008-02-03 Yoshinori K. Okuji <okuji@enbug.org>

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Add support for having a grub directory in a different drive. This
    is still only the data handling part.

    * kern/i386/pc/startup.S (multiboot_trampoline): Set %dh to 0xFF.
    (codestart): Save %dh in GRUB_ROOT_DRIVE.
    (grub_root_drive): New variable.

    * kern/i386/pc/init.c (make_install_device): Use GRUB_ROOT_DRIVE
    instead of GRUB_BOOT_DRIVE to construct a device name. Set
    GRUB_ROOT_DRIVE to GRUB_BOOT_DRIVE if it is 0xFF, otherwise use it
    as it was.

    * include/grub/i386/pc/kernel.h (grub_root_drive): New prototype.

    * include/grub/i386/pc/boot.h (GRUB_BOOT_MACHINE_ROOT_DRIVE): New
    macro.
    (GRUB_BOOT_MACHINE_DRIVE_CHECK): Set to 0x4f.

    * boot/i386/pc/pxeboot.S (_start): Set %dh to 0xFF. For now, this
    is bogus, because PXE booting does not specify any drive
    correctly.

    * boot/i386/pc/lnxboot.S (reg_edx): Set the second byte to 0xFF. I
    am not sure if this is really correct.

    * boot/i386/pc/cdboot.S: Set %dh to 0xFF, because the root drive
    is always identical to the boot drive when booting from a CD.

    * boot/i386/pc/boot.S (MOV_MEM_TO_AL): Removed. Not needed any
    longer.
    (root_drive): New variable.
    (real_start): Unconditionally set %dh to ROOT_DRIVE.
    (setup_sectors): Push %dx right after popping it, because %dh will
    be modified later.
    (copy_buffer): Restore %dx.
This commit is contained in:
okuji 2008-02-03 18:56:08 +00:00
parent e0ca067708
commit 9be6b98b6f
9 changed files with 78 additions and 15 deletions
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11
boot/i386/pc/boot.S
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@ -32,9 +32,6 @@
/* Print message string */
#define MSG(x) movw $ABS(x), %si; call message
/* XXX: binutils-2.9.1.0.x doesn't produce a short opcode for this. */
#define MOV_MEM_TO_AL(x) .byte 0xa0; .word x
.file "boot.S"
.text
@ -99,6 +96,8 @@ kernel_sector:
boot_drive:
.byte 0xff /* the disk to load kernel from */
/* 0xff means use the boot drive */
root_drive:
.byte 0xff
after_BPB:
@ -141,7 +140,9 @@ real_start:
/*
* Check if we have a forced disk reference here
*/
MOV_MEM_TO_AL(ABS(boot_drive)) /* movb ABS(boot_drive), %al */
/* assign root_drive at the same time */
movw ABS(boot_drive), %ax
movb %ah, %dh
cmpb $0xff, %al
je 1f
movb %al, %dl
@ -303,6 +304,7 @@ setup_sectors:
/* restore %dl */
popw %dx
pushw %dx
/* head start */
movb %al, %dh
@ -353,6 +355,7 @@ copy_buffer:
popw %ds
popa
popw %dx
/* boot kernel */
jmp *(kernel_address)