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* The MBR boot code did execute the check for disk extensions with the wrong

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magic code. This would lead to them not being detected on systems where the
  BIOS (rightfully) returns an error in this case. Since the CHS fallback can't
  work it would then fail with "Missing Operating System".
* Fixed a typo, an 80 char limit violation.
* Automatic whitespace cleanup.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35718 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Michael Lotz 2010-03-02 01:28:49 +00:00
parent aceebab740
commit 1487898473
1 changed files with 6 additions and 6 deletions
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12
src/bin/writembr/mbr.S
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@ -37,7 +37,7 @@ start: cld // String ops inc
/* /*
* Relocate ourself to a lower address so that we are out of the way when * Relocate ourself to a lower address so that we are out of the way when
* we load in the bootstrap from the partition to boot. * we load in the bootstrap from the partition to boot.
*/ */
movw $main-EXEC+LOAD, %si // Source movw $main-EXEC+LOAD, %si // Source
movw $main, %di // Destination movw $main, %di // Destination
movw $0x200-(main-start), %cx // Byte count movw $0x200-(main-start), %cx // Byte count
@ -94,7 +94,7 @@ main.5: movw %sp, %di // Save stack pointer
jnz main.7 // No. jnz main.7 // No.
pushw %cx // Save %cx pushw %cx // Save %cx
pushw %bx // Save %bx pushw %bx // Save %bx
movw $MAGIC, %bx // Magic movw $0x55aa, %bx // Reversed Magic
movb $0x41, %ah // BIOS: EDD extensions present? movb $0x41, %ah // BIOS: EDD extensions present?
int $0x13 // int $0x13 //
jc main.6 // No. jc main.6 // No.
@ -109,7 +109,7 @@ main.5: movw %sp, %di // Save stack pointer
pushw %bx // the transfer buffer pushw %bx // the transfer buffer
pushw $0x1 // Read 1 sector pushw $0x1 // Read 1 sector
pushw $0x10 // Packet length pushw $0x10 // Packet length
movw %sp, %si // Packer pointer movw %sp, %si // Packet pointer
movw $0x4200, %ax // BIOS: LBA Read from disk movw $0x4200, %ax // BIOS: LBA Read from disk
jmp main.8 // Skip the CHS setup jmp main.8 // Skip the CHS setup
main.6: popw %bx // Restore %bx main.6: popw %bx // Restore %bx
@ -119,8 +119,8 @@ main.8: int $0x13 // Call the BIOS
movw %di,%sp // Restore stack movw %di,%sp // Restore stack
jc err_loading_os // If error jc err_loading_os // If error
/* /*
* Now that we've loaded the bootstrap, check for the magic 0xaa55 signature. If it * Now that we've loaded the bootstrap, check for the magic 0xaa55 signature.
* is present, execute the bootstrap we just loaded. * If it is present, execute the bootstrap we just loaded.
*/ */
cmpw $MAGIC, 0x1fe(%bx) // Bootable? cmpw $MAGIC, 0x1fe(%bx) // Bootable?
jne err_missing_os // No jne err_missing_os // No
@ -141,7 +141,7 @@ err_missing_os:
jmp putString // jmp putString //
/* /*
* Output an ASCIZ string to the console via the BIOS. * Output an ASCIZ string to the console via the BIOS.
*/ */
putString.0: putString.0:
movw $0x7, %bx // Page:attribute movw $0x7, %bx // Page:attribute
movb $0xe, %ah // BIOS: Display character movb $0xe, %ah // BIOS: Display character