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[romprefix] Force PnP header to a 16-byte boundary for IBM BIOSes

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IBM BIOSes ignore the PnP header offset stored at address 0x1a and
instead scan for the $PnP signature on a 16-byte boundary.  (This
alignment is not mandated by the PnP specification.)

Force PnP header to a 16-byte boundary to work around these BIOSes.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2011-05-17 22:48:52 +01:00
parent fcd55f7500
commit d4f0c5d088
1 changed files with 5 additions and 0 deletions
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5
src/arch/i386/prefix/romprefix.S
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@ -104,6 +104,11 @@ pciheader_runtime_length:
.long 0
.previous
/* PnP doesn't require any particular alignment, but IBM
* BIOSes will scan on 16-byte boundaries rather than using
* the offset stored at 0x1a
*/
.align 16
pnpheader:
.ascii "$PnP" /* Signature */
.byte 0x01 /* Structure revision */