[PATCH] x86: fix usage of bios intcall()

From: Akinobu Mita
Date: Tue Jun 30 2009 - 22:13:23 EST


Some intcall() misuses the input biosregs as output in
cf06de7b9cdd3efee7a59dced1977b3c21d43732

This fixes the problem vga=ask boot option doesn't show enough modes.

Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
---
arch/x86/boot/video-bios.c | 3 +--
arch/x86/boot/video-vesa.c | 4 ++--
2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/boot/video-bios.c b/arch/x86/boot/video-bios.c
index d660be4..49e0c18 100644
--- a/arch/x86/boot/video-bios.c
+++ b/arch/x86/boot/video-bios.c
@@ -37,14 +37,13 @@ static int set_bios_mode(u8 mode)
ireg.al = mode; /* AH=0x00 Set Video Mode */
intcall(0x10, &ireg, NULL);

-
ireg.ah = 0x0f; /* Get Current Video Mode */
intcall(0x10, &ireg, &oreg);

do_restore = 1; /* Assume video contents were lost */

/* Not all BIOSes are clean with the top bit */
- new_mode = ireg.al & 0x7f;
+ new_mode = oreg.al & 0x7f;

if (new_mode == mode)
return 0; /* Mode change OK */
diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index c700147..275dd17 100644
--- a/arch/x86/boot/video-vesa.c
+++ b/arch/x86/boot/video-vesa.c
@@ -45,7 +45,7 @@ static int vesa_probe(void)
ireg.di = (size_t)&vginfo;
intcall(0x10, &ireg, &oreg);

- if (ireg.ax != 0x004f ||
+ if (oreg.ax != 0x004f ||
vginfo.signature != VESA_MAGIC ||
vginfo.version < 0x0102)
return 0; /* Not present */
@@ -70,7 +70,7 @@ static int vesa_probe(void)
ireg.di = (size_t)&vminfo;
intcall(0x10, &ireg, &oreg);

- if (ireg.ax != 0x004f)
+ if (oreg.ax != 0x004f)
continue;

if ((vminfo.mode_attr & 0x15) == 0x05) {
--
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