From: Zwane Mwaikambo This patch is for the following bug, thanks to Ondrej Zary for reporting, testing and submitting a patch. http://bugzilla.kernel.org/show_bug.cgi?id=3767 It appears that the Cyrix MII won't touch %ecx at all resulting in stale data being returned as extended attributes, so clear ecx before issuing the cpuid. I have also made the capability print code display all the capability words for easier debugging in future. Signed-off-by: Zwane Mwaikambo Signed-off-by: Andrew Morton --- 25-akpm/arch/i386/kernel/cpu/common.c | 29 +++++++++++++---------------- 25-akpm/include/asm-i386/processor.h | 4 +++- 2 files changed, 16 insertions(+), 17 deletions(-) diff -puN arch/i386/kernel/cpu/common.c~cyrix-mii-cpuid-returns-stale-%ecx arch/i386/kernel/cpu/common.c --- 25/arch/i386/kernel/cpu/common.c~cyrix-mii-cpuid-returns-stale-%ecx 2004-11-30 21:48:29.416596704 -0800 +++ 25-akpm/arch/i386/kernel/cpu/common.c 2004-11-30 21:48:29.422595792 -0800 @@ -334,21 +334,19 @@ void __init identify_cpu(struct cpuinfo_ generic_identify(c); - printk(KERN_DEBUG "CPU: After generic identify, caps: %08lx %08lx %08lx %08lx\n", - c->x86_capability[0], - c->x86_capability[1], - c->x86_capability[2], - c->x86_capability[3]); + printk(KERN_DEBUG "CPU: After generic identify, caps:"); + for (i = 0; i < NCAPINTS; i++) + printk(" %08lx", c->x86_capability[i]); + printk("\n"); if (this_cpu->c_identify) { this_cpu->c_identify(c); - printk(KERN_DEBUG "CPU: After vendor identify, caps: %08lx %08lx %08lx %08lx\n", - c->x86_capability[0], - c->x86_capability[1], - c->x86_capability[2], - c->x86_capability[3]); -} + printk(KERN_DEBUG "CPU: After vendor identify, caps:"); + for (i = 0; i < NCAPINTS; i++) + printk(" %08lx", c->x86_capability[i]); + printk("\n"); + } /* * Vendor-specific initialization. In this section we @@ -398,11 +396,10 @@ void __init identify_cpu(struct cpuinfo_ /* Now the feature flags better reflect actual CPU features! */ - printk(KERN_DEBUG "CPU: After all inits, caps: %08lx %08lx %08lx %08lx\n", - c->x86_capability[0], - c->x86_capability[1], - c->x86_capability[2], - c->x86_capability[3]); + printk(KERN_DEBUG "CPU: After all inits, caps:"); + for (i = 0; i < NCAPINTS; i++) + printk(" %08lx", c->x86_capability[i]); + printk("\n"); /* * On SMP, boot_cpu_data holds the common feature set between diff -puN include/asm-i386/processor.h~cyrix-mii-cpuid-returns-stale-%ecx include/asm-i386/processor.h --- 25/include/asm-i386/processor.h~cyrix-mii-cpuid-returns-stale-%ecx 2004-11-30 21:48:29.417596552 -0800 +++ 25-akpm/include/asm-i386/processor.h 2004-11-30 21:48:29.421595944 -0800 @@ -126,6 +126,8 @@ extern void dodgy_tsc(void); /* * Generic CPUID function + * clear %ecx since some cpus (Cyrix MII) do not set or clear %ecx + * resulting in stale register contents being returned. */ static inline void cpuid(int op, int *eax, int *ebx, int *ecx, int *edx) { @@ -134,7 +136,7 @@ static inline void cpuid(int op, int *ea "=b" (*ebx), "=c" (*ecx), "=d" (*edx) - : "0" (op)); + : "0" (op), "c"(0)); } /* _