Date: Sun, 5 Aug 2012 12:57:38 +0000 (UTC) From: "Andrey V. Elsukov" <ae@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r239060 - head/sys/boot/i386/pmbr Message-ID: <201208051257.q75CvcqA085421@svn.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: ae Date: Sun Aug 5 12:57:38 2012 New Revision: 239060 URL: http://svn.freebsd.org/changeset/base/239060 Log: When GPT signature is invalid in the primary GPT header, then try to read backup GPT header. Submitted by: hrs (previous version) Modified: head/sys/boot/i386/pmbr/pmbr.s Modified: head/sys/boot/i386/pmbr/pmbr.s ============================================================================== --- head/sys/boot/i386/pmbr/pmbr.s Sun Aug 5 12:16:11 2012 (r239059) +++ head/sys/boot/i386/pmbr/pmbr.s Sun Aug 5 12:57:38 2012 (r239060) @@ -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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201208051257.q75CvcqA085421>