lkml.org 
[lkml]   [2008]   [Aug]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: Setup code crashes my old 486 box
Joerg Roedel wrote:
> Hello,
>
> 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.
> Is this an acceptable workaround or is there a better one for this?
>
> Regards,
>
> Joerg

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?

-hpa
diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index a34b998..9ce8d29 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -242,6 +242,12 @@ int cmdline_find_option(const char *option, char *buffer, int bufsize);
int cmdline_find_option_bool(const char *option);

/* cpu.c, cpucheck.c */
+struct cpu_features {
+ int level; /* Family, or 64 for x86-64 */
+ int model;
+ u32 flags[NCAPINTS];
+};
+extern struct cpu_features cpu;
int check_cpu(int *cpu_level_ptr, int *req_level_ptr, u32 **err_flags_ptr);
int validate_cpu(void);

diff --git a/arch/x86/boot/cpucheck.c b/arch/x86/boot/cpucheck.c
index 7804389..c1ce030 100644
--- a/arch/x86/boot/cpucheck.c
+++ b/arch/x86/boot/cpucheck.c
@@ -30,13 +30,7 @@
#include <asm/required-features.h>
#include <asm/msr-index.h>

-struct cpu_features {
- int level; /* Family, or 64 for x86-64 */
- int model;
- u32 flags[NCAPINTS];
-};
-
-static struct cpu_features cpu;
+struct cpu_features cpu;
static u32 cpu_vendor[3];
static u32 err_flags[NCAPINTS];

diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
index 2296164..9b04773 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 < 5)
+ return;
+
asm("int $0x15"
: "=a" (boot_params.ist_info.signature),
"=b" (boot_params.ist_info.command),
\
 
 \ /
  Last update: 2008-08-13 01:01    [W:0.062 / U:3.352 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site