diff options
| author | ae <ae@FreeBSD.org> | 2012-08-05 12:57:38 +0000 |
|---|---|---|
| committer | ae <ae@FreeBSD.org> | 2012-08-05 12:57:38 +0000 |
| commit | 7d0b9e919063866ecf0618822070b8cb60af52c0 (patch) | |
| tree | b47c5e1de4eedbfcc806f72495c98f82b6cf98c8 /sys/boot/i386 | |
| parent | 53f13e0527cdd085c670d34e5ad0b018a4ce648e (diff) | |
| download | FreeBSD-src-7d0b9e919063866ecf0618822070b8cb60af52c0.zip FreeBSD-src-7d0b9e919063866ecf0618822070b8cb60af52c0.tar.gz | |
When GPT signature is invalid in the primary GPT header, then try to
read backup GPT header.
Submitted by: hrs (previous version)
Diffstat (limited to 'sys/boot/i386')
| -rw-r--r-- | sys/boot/i386/pmbr/pmbr.s | 43 |
1 files changed, 36 insertions, 7 deletions
diff --git a/sys/boot/i386/pmbr/pmbr.s b/sys/boot/i386/pmbr/pmbr.s index 8acdef2..1a75881 100644 --- a/sys/boot/i386/pmbr/pmbr.s +++ b/sys/boot/i386/pmbr/pmbr.s @@ -42,8 +42,8 @@ .set STACK,EXEC+SECSIZE*4 # Stack address .set GPT_ADDR,STACK # GPT header address .set GPT_SIG,0 - .set GPT_SIG_0,0x20494645 - .set GPT_SIG_1,0x54524150 + .set GPT_SIG_0,0x20494645 # "EFI " + .set GPT_SIG_1,0x54524150 # "PART" .set GPT_MYLBA,24 .set GPT_PART_LBA,72 .set GPT_NPART,80 @@ -52,6 +52,8 @@ .set PART_TYPE,0 .set PART_START_LBA,32 .set PART_END_LBA,40 + .set DPBUF,PART_ADDR+SECSIZE + .set DPBUF_SEC,0x10 # Number of sectors .set NHRDRV,0x475 # Number of hard drives @@ -91,15 +93,32 @@ main: cmpb $0x80,%dl # Drive valid? jb main.2 # Yes main.1: movb $0x80,%dl # Assume drive 0x80 # -# Load the primary GPT header from LBA 1 and verify signature. +# Load the GPT header and verify signature. Try LBA 1 for the primary one and +# the last LBA for the backup if it is broken. # -main.2: movw $GPT_ADDR,%bx +main.2: call getdrvparams # Read drive parameters + movb $1,%dh # %dh := 1 (reading primary) +main.2a: movw $GPT_ADDR,%bx movw $lba,%si - call read + call read # Read header and check GPT sig cmpl $GPT_SIG_0,GPT_ADDR+GPT_SIG - jnz err_pt + jnz main.2b cmpl $GPT_SIG_1,GPT_ADDR+GPT_SIG+4 - jnz err_pt + jnz main.2b + jmp load_part +main.2b: cmpb $1,%dh # Reading primary? + jne err_pt # If no - invalid table found +# +# Try alternative LBAs from the last sector for the GPT header. +# +main.3: movb $0,%dh # %dh := 0 (reading backup) + movw $DPBUF+DPBUF_SEC,%si # %si = last sector + 1 + movw $lba,%di # %di = $lba +main.3a: decl (%si) # 0x0(%si) = last sec (0-31) + movw $2,%cx + rep + movsw # $lastsec--, copy it to $lba + jmp main.2a # Read the next sector # # Load a partition table sector from disk and look for a FreeBSD boot # partition. @@ -172,6 +191,16 @@ read: pushl 0x4(%si) # Set the LBA jc err_rd # If error ret # +# Check the number of LBAs on the drive index %dx. Trashes %ax and %si. +# +getdrvparams: + movw $DPBUF,%si # Set the address of result buf + movw $0x001e,(%si) # len + movw $0x4800,%ax # BIOS: Read Drive Parameters + int $0x13 # Call the BIOS + jc err_rd # "I/O error" if error + ret +# # Various error message entry points. # err_big: movw $msg_big,%si # "Boot loader too |
