[SeaBIOS] [PATCH 7/7] vgabios: PMM scan was incorrectly depending on a zero %ds segment.
Kevin O'Connor
kevin at koconnor.net
Mon Apr 7 01:00:48 CEST 2014
Make sure the PMM scanning code uses the GET_FARVAR macro. (The
existing code only worked because SeaBIOS happens to call the vgabios
in bigreal mode with %ds == %ss = 0.) Also, the scan doesn't require
bigreal mode - use accesses relative to the SEG_BIOS segment so that
the scan can work in regular real mode.
Signed-off-by: Kevin O'Connor <kevin at koconnor.net>
---
vgasrc/vgainit.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/vgasrc/vgainit.c b/vgasrc/vgainit.c
index 33b8eb9..6d9a224 100644
--- a/vgasrc/vgainit.c
+++ b/vgasrc/vgainit.c
@@ -60,14 +60,14 @@ allocate_extra_stack(void)
{
if (!CONFIG_VGA_ALLOCATE_EXTRA_STACK)
return;
- void *pmmscan = (void*)BUILD_BIOS_ADDR;
- for (; pmmscan < (void*)BUILD_BIOS_ADDR+BUILD_BIOS_SIZE; pmmscan+=16) {
- struct pmmheader *pmm = pmmscan;
- if (pmm->signature != PMM_SIGNATURE)
+ u32 pmmscan;
+ for (pmmscan=0; pmmscan < BUILD_BIOS_SIZE; pmmscan+=16) {
+ struct pmmheader *pmm = (void*)pmmscan;
+ if (GET_FARVAR(SEG_BIOS, pmm->signature) != PMM_SIGNATURE)
continue;
- if (checksum_far(0, pmm, pmm->length))
+ if (checksum_far(SEG_BIOS, pmm, GET_FARVAR(SEG_BIOS, pmm->length)))
continue;
- struct segoff_s entry = pmm->entry;
+ struct segoff_s entry = GET_FARVAR(SEG_BIOS, pmm->entry);
dprintf(1, "Attempting to allocate VGA stack via pmm call to %04x:%04x\n"
, entry.seg, entry.offset);
u16 res1, res2;
--
1.9.0
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