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authorH. Peter Anvin <hpa@zytor.com>2007-08-31 11:30:31 -0700
committerH. Peter Anvin <hpa@zytor.com>2007-08-31 11:52:35 -0700
commit4221d014ea04d439e6d1e65951c3b406e7c1b7ab (patch)
tree68457ec6ff8fbaeefa0a3b9e5565d8c10a20643f
parent3b42d28b2a04b3c9830eb865288239d45eccc402 (diff)
[x86 setup] Don't rely on the VESA BIOS being register-clean
The VESA BIOS is specified to be register-clean. However, we have now found at least one system which violates that. Thus, be as paranoid about VESA calls as about everything else. Huge thanks to Will Simoneau for reporting, diagnosing, and testing this out on Dell Inspiron 5150. Cc: Will Simoneau <simoneau@ele.uri.edu> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--arch/i386/boot/video-vesa.c34
1 files changed, 21 insertions, 13 deletions
diff --git a/arch/i386/boot/video-vesa.c b/arch/i386/boot/video-vesa.c
index f1bc71e948cf..192190710710 100644
--- a/arch/i386/boot/video-vesa.c
+++ b/arch/i386/boot/video-vesa.c
@@ -29,7 +29,7 @@ static void vesa_store_mode_params_graphics(void);
static int vesa_probe(void)
{
#if defined(CONFIG_VIDEO_VESA) || defined(CONFIG_FIRMWARE_EDID)
- u16 ax;
+ u16 ax, cx, di;
u16 mode;
addr_t mode_ptr;
struct mode_info *mi;
@@ -39,9 +39,11 @@ static int vesa_probe(void)
vginfo.signature = VBE2_MAGIC;
- /* Optimistically assume a VESA BIOS is register-clean... */
ax = 0x4f00;
- asm("int $0x10" : "+a" (ax), "=m" (vginfo) : "D" (&vginfo));
+ di = (size_t)&vginfo;
+ asm(INT10
+ : "+a" (ax), "+D" (di), "=m" (vginfo)
+ : : "ebx", "ecx", "edx", "esi");
if (ax != 0x004f ||
vginfo.signature != VESA_MAGIC ||
@@ -64,9 +66,11 @@ static int vesa_probe(void)
memset(&vminfo, 0, sizeof vminfo); /* Just in case... */
ax = 0x4f01;
- asm("int $0x10"
- : "+a" (ax), "=m" (vminfo)
- : "c" (mode), "D" (&vminfo));
+ cx = mode;
+ di = (size_t)&vminfo;
+ asm(INT10
+ : "+a" (ax), "+c" (cx), "+D" (di), "=m" (vminfo)
+ : : "ebx", "edx", "esi");
if (ax != 0x004f)
continue;
@@ -102,16 +106,18 @@ static int vesa_probe(void)
static int vesa_set_mode(struct mode_info *mode)
{
- u16 ax;
+ u16 ax, bx, cx, di;
int is_graphic;
u16 vesa_mode = mode->mode - VIDEO_FIRST_VESA;
memset(&vminfo, 0, sizeof vminfo); /* Just in case... */
ax = 0x4f01;
- asm("int $0x10"
- : "+a" (ax), "=m" (vminfo)
- : "c" (vesa_mode), "D" (&vminfo));
+ cx = vesa_mode;
+ di = (size_t)&vminfo;
+ asm(INT10
+ : "+a" (ax), "+c" (cx), "+D" (di), "=m" (vminfo)
+ : : "ebx", "edx", "esi");
if (ax != 0x004f)
return -1;
@@ -129,9 +135,11 @@ static int vesa_set_mode(struct mode_info *mode)
ax = 0x4f02;
- asm volatile("int $0x10"
- : "+a" (ax)
- : "b" (vesa_mode), "D" (0));
+ bx = vesa_mode;
+ di = 0;
+ asm volatile(INT10
+ : "+a" (ax), "+b" (bx), "+D" (di)
+ : : "ecx", "edx", "esi");
if (ax != 0x004f)
return -1;