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[romprefix] Attempt to gracefully handle semi-PnP IBM BIOSes 

Some IBM BIOSes provide partial support for PnP: they will use the BEV
entry point but will not advertise PnP support.  This causes iPXE to
hook INT 19, which disrupts the boot process.

Attempt to improve this situation by detecting an IBM BIOS and
treating it as a PnP BIOS despite the absence of a PnP signature.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/5/head
Michael Brown 2011-05-04 10:04:43 +01:00
parent 0b6808aadc
commit 38cd351243
1 changed files with 20 additions and 6 deletions
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26
src/arch/i386/prefix/romprefix.S
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@ -13,6 +13,7 @@ FILE_LICENCE ( GPL2_OR_LATER )
#define PNP_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'n' << 16 ) + ( 'P' << 24 ) )
#define PMM_SIGNATURE ( '$' + ( 'P' << 8 ) + ( 'M' << 16 ) + ( 'M' << 24 ) )
#define PCI_SIGNATURE ( 'P' + ( 'C' << 8 ) + ( 'I' << 16 ) + ( ' ' << 24 ) )
#define IBM_SIGNATURE ( ( 'I' << 24 ) + ( 'B' << 16 ) + ( 'M' << 8 ) + ' ' )
#define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) )
#define PMM_ALLOCATE 0x0000
#define PMM_FIND 0x0001
@ -172,6 +173,7 @@ undiheader:
init:
/* Preserve registers, clear direction flag, set %ds=%cs */
pushaw
pushl %ebx
pushw %ds
pushw %es
pushw %fs
@ -180,15 +182,14 @@ init:
pushw %cs
popw %ds
/* Shuffle some registers around. We need %di available for
* the print_xxx functions, and in a register that's
* addressable from %es, so shuffle as follows:
/* Shuffle some registers around. We need to use %di for the
* print_xxx functions, so shuffle as follows:
*
* %di (pointer to PnP structure) => %bx
* %bx (runtime segment address, for PCI 3.0) => %gs
* %edi (IBM signature) => %ebx
*/
movw %bx, %gs
movw %di, %bx
movl %edi, %ebx
/* Store PCI bus:dev.fn address */
movw %ax, init_pci_busdevfn
@ -263,7 +264,16 @@ no_pci3:
popl %edx
popl %ebx
/* Check for PnP BIOS. Although %es:di should point to the
/* Check for IBM BIOS, which uses the PnP entry points but
* doesn't indicate PnP support.
*/
cmpl $IBM_SIGNATURE, %ebx
jne no_ibm
movw $init_message_ibm, %si
xorw %di, %di
call print_message
jmp pnp_done
no_ibm: /* Check for PnP BIOS. Although %es:di should point to the
* PnP BIOS signature on entry, some BIOSes fail to do this.
*/
movw $( 0xf000 - 1 ), %bx
@ -416,6 +426,7 @@ no_pmm:
popw %fs
popw %es
popw %ds
popl %ebx
popaw
/* Indicate boot capability to PnP BIOS, if present */
@ -530,6 +541,9 @@ init_message:
init_message_pci:
.asciz " PCI"
.size init_message_pci, . - init_message_pci
init_message_ibm:
.asciz " IBM"
.size init_message_ibm, . - init_message_ibm
init_message_pnp:
.asciz " PnP"
.size init_message_pnp, . - init_message_pnp