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| author | Michael Brown | 2008-10-17 19:12:24 +0200 |
|---|---|---|
| committer | Michael Brown | 2008-10-17 19:12:24 +0200 |
| commit | 5600955bdd20d95d6509617457cfa9d0d7b464b7 (patch) | |
| tree | 55a1e9bfb38b526698a102a83286784a6c681792 /src/arch/i386/prefix/romprefix.S | |
| parent | [build] Use ".bss.*" names for uninitialised-data sections (diff) | |
| download | ipxe-5600955bdd20d95d6509617457cfa9d0d7b464b7.tar.gz ipxe-5600955bdd20d95d6509617457cfa9d0d7b464b7.tar.xz ipxe-5600955bdd20d95d6509617457cfa9d0d7b464b7.zip | |
[romprefix] Sanity-check the runtime segment address for PCI 3
Some PCI 3 BIOSes seem to provide a garbage value in %bx, which should
contain the runtime segment address. Perform a basic sanity check: we
reject the segment if it is below the start of option ROM space. If
the sanity check fails, we assume that the BIOS was not expecting us
to be a PCI 3 ROM, and we just leave our image in situ.
Diffstat (limited to 'src/arch/i386/prefix/romprefix.S')
| -rw-r--r-- | src/arch/i386/prefix/romprefix.S | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S index ca32a441..3351494b 100644 --- a/src/arch/i386/prefix/romprefix.S +++ b/src/arch/i386/prefix/romprefix.S @@ -205,7 +205,16 @@ init: movb %bl, %al call print_hex_byte cmpb $3, %bh + jb 1f + /* PCI >=3.0: leave %gs as-is if sane */ + movw %gs, %ax + cmpw $0xc000, %ax jae 2f + /* PCI 3.0 with insane %gs value: print error and ignore %gs */ + movb $'!', %al + call print_character + movw %gs, %ax + call print_hex_word 1: /* PCI <3.0: set %gs (runtime segment) = %cs (init-time segment) */ pushw %cs popw %gs |