From 7b27718bdb1b70166383dec91391df5534d449ee Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Wed, 13 Aug 2008 10:07:05 +0200 Subject: x86: fix setup code crashes on my old 486 box yesterday I tried to reactivate my old 486 box and wanted to install a current Linux with latest kernel on it. But it turned out that the latest kernel does not boot because the machine crashes early in the setup code. After some debugging it turned out that the problem is the query_ist() function. If this interrupt with that function is called the machine simply locks up. It looks like a BIOS bug. Looking for a workaround for this problem I wrote the attached patch. It checks for the CPUID instruction and if it is not implemented it does not call the speedstep BIOS function. As far as I know speedstep should be available since some Pentium earliest. Alan Cox observed that it's available since the Pentium II, so cpuid levels 4 and 5 can be excluded altogether. H. Peter Anvin cleaned up the code some more: > Right in concept, but I dislike the implementation (duplication of the > CPU detect code we already have). Could you try this patch and see if > it works for you? which, with a small modification to fix a build error with it the resulting kernel boots on my machine. Signed-off-by: Joerg Roedel Signed-off-by: "H. Peter Anvin" Cc: Signed-off-by: Ingo Molnar --- arch/x86/boot/main.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86/boot/main.c') diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c index 2296164b54d..01aa64b5575 100644 --- a/arch/x86/boot/main.c +++ b/arch/x86/boot/main.c @@ -73,6 +73,10 @@ static void keyboard_set_repeat(void) */ static void query_ist(void) { + /* Some 486 BIOSes apparently crash on this call */ + if (cpu.level < 6) + return; + asm("int $0x15" : "=a" (boot_params.ist_info.signature), "=b" (boot_params.ist_info.command), -- cgit v1.2.3-70-g09d2 From c2dcfde8274883e1f6050784dcbd34b01e824b91 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Wed, 13 Aug 2008 13:14:22 -0700 Subject: x86: cleanup for setup code crashes during IST probe Clean up the code for crashes during SpeedStep probing on older machines. Signed-off-by: H. Peter Anvin Signed-off-by: Ingo Molnar --- arch/x86/boot/boot.h | 4 ++-- arch/x86/boot/cpu.c | 3 --- arch/x86/boot/cpucheck.c | 2 -- arch/x86/boot/main.c | 3 ++- 4 files changed, 4 insertions(+), 8 deletions(-) (limited to 'arch/x86/boot/main.c') diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h index 9d4b4b43d97..616b804a229 100644 --- a/arch/x86/boot/boot.h +++ b/arch/x86/boot/boot.h @@ -24,8 +24,8 @@ #include #include #include - -#define NCAPINTS 8 +#include "bitops.h" +#include /* Useful macros */ #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) diff --git a/arch/x86/boot/cpu.c b/arch/x86/boot/cpu.c index 92d6fd73dc7..75298fe2edc 100644 --- a/arch/x86/boot/cpu.c +++ b/arch/x86/boot/cpu.c @@ -16,9 +16,6 @@ */ #include "boot.h" -#include "bitops.h" -#include - #include "cpustr.h" static char *cpu_name(int level) diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c index c1ce0303d99..4b9ae7c5674 100644 --- a/arch/x86/boot/cpucheck.c +++ b/arch/x86/boot/cpucheck.c @@ -22,10 +22,8 @@ #ifdef _SETUP # include "boot.h" -# include "bitops.h" #endif #include -#include #include #include #include diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c index 01aa64b5575..197421db1af 100644 --- a/arch/x86/boot/main.c +++ b/arch/x86/boot/main.c @@ -73,7 +73,8 @@ static void keyboard_set_repeat(void) */ static void query_ist(void) { - /* Some 486 BIOSes apparently crash on this call */ + /* Some older BIOSes apparently crash on this call, so filter + it from machines too old to have SpeedStep at all. */ if (cpu.level < 6) return; -- cgit v1.2.3-70-g09d2