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[romprefix] On a PCI3.0, non-BBS system, use the correct %cs for INT19

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On a system that doesn't support BBS, we end up hooking INT19 to gain
control of the boot process.  If the system is PCI3.0, we must take
care to use the runtime value for %cs, rather than the POST-time
value, otherwise we end up pointing INT19 to the temporary option ROM
POST scratch area.
This commit is contained in:
Michael Brown 2008-08-22 03:01:46 +01:00
parent 4815188dfc
commit 82baea0a4b
1 changed files with 45 additions and 26 deletions
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71
src/arch/i386/prefix/romprefix.S
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@ -144,6 +144,7 @@ init:
popw %ds
pushw $0x40
popw %fs
/* 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:
@ -153,21 +154,53 @@ init:
*/
movw %bx, %gs
movw %di, %bx
/* Print message as early as possible */
movw $init_message, %si
xorw %di, %di
call print_message
call print_pci_busdevfn
/* Fill in product name string, if possible */
movw $prodstr_pci_id, %di
call print_pci_busdevfn
movb $' ', prodstr_separator
/* Print segment address */
movb $' ', %al
xorw %di, %di
call print_character
movw %cs, %ax
call print_hex_word
/* Check for PCI BIOS version */
pushl %ebx
pushl %edx
stc
movw $0xb101, %ax
int $0x1a
jc 1f
cmpl $PCI_SIGNATURE, %edx
jne 1f
testb %ah, %ah
jnz 1f
movw $init_message_pci, %si
xorw %di, %di
call print_message
movb %bh, %al
call print_hex_nibble
movb $'.', %al
call print_character
movb %bl, %al
call print_hex_byte
cmpb $3, %bh
jae 2f
1: /* PCI <3.0: set %gs (runtime segment) = %cs (init-time segment) */
pushw %cs
popw %gs
2: popl %edx
popl %ebx
/* Check for PnP BIOS */
testw $0x0f, %bx /* PnP signature must be aligned - bochs */
jnz hook_int19 /* uses unalignment to indicate 'fake' PnP. */
@ -177,6 +210,7 @@ init:
movw $init_message_pnp, %si
xorw %di, %di
call print_message
/* Check for BBS */
pushw %es:0x1b(%bx) /* Real-mode data segment */
pushw %ds /* &(bbs_version) */
@ -199,10 +233,11 @@ hook_int19:
movw %ax, %es
pushl %es:( 0x19 * 4 )
popl orig_int19
pushw %cs
pushw %gs /* %gs contains runtime %cs */
pushw $int19_entry
popl %es:( 0x19 * 4 )
hook_bbs:
/* Check for PMM */
movw $( 0xe000 - 1 ), %bx
pmm_scan:
@ -259,29 +294,11 @@ gotpmm: /* PMM allocation succeeded: copy ROM to PMM block */
subb %bl, checksum
popal
no_pmm:
/* Check for PCI BIOS */
pushl %edx
stc
movw $0xb101, %ax
int $0x1a
jc no_pci
cmpl $PCI_SIGNATURE, %edx
popl %edx
jne no_pci
testb %ah, %ah
jnz no_pci
movw $init_message_pci, %si
xorw %di, %di
call print_message
movb %bh, %al
call print_hex_nibble
movb $'.', %al
call print_character
movb %bl, %al
call print_hex_byte
cmpb $3, %bh
jb no_pci3
/* Copy self to option ROM space (required for PCI3.0) */
/* Copy self to option ROM space. Required for PCI3.0, which
* loads us to a temporary location in low memory. Will be a
* no-op for lower PCI versions.
*/
movb $' ', %al
xorw %di, %di
call print_character
@ -293,8 +310,7 @@ no_pmm:
xorw %si, %si
xorw %di, %di
cs rep movsb
no_pci3:
no_pci:
/* Prompt for POST-time shell */
movw $init_message_prompt, %si
xorw %di, %di
@ -338,16 +354,19 @@ wait_for_key:
pushw %cs
call exec
no_key_pressed:
/* Print blank lines to terminate messages */
movw $init_message_end, %si
xorw %di, %di
call print_message
/* Restore registers */
popw %gs
popw %fs
popw %es
popw %ds
popaw
/* Indicate boot capability to PnP BIOS, if present */
movw $0x20, %ax
lret