From 4221d014ea04d439e6d1e65951c3b406e7c1b7ab Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 31 Aug 2007 11:30:31 -0700 Subject: [PATCH] [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 Signed-off-by: H. Peter Anvin --- arch/i386/boot/video-vesa.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) diff --git a/arch/i386/boot/video-vesa.c b/arch/i386/boot/video-vesa.c index f1bc71e948..1921907107 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; -- 2.39.5