From 63d38198a0f57dca87e6cb79931c7bedbb7ab069 Mon Sep 17 00:00:00 2001 From: Alok Kataria Date: Mon, 7 Apr 2008 11:38:33 -0700 Subject: [PATCH] x86: fix paranoia about using BIOS quickboot mechanism. > > Make sure that we clear the "shutdown status flag" in the CMOS > > register after each CPU is brought up. This fixes a problem where the > > "shutdown status flag" may remain set when a CPU is brought up after > > booting. > > btw., what problem does this result in, exactly? The shutdown status flag set to "0xA", corresponds to "JMP double word request without INT init". This JMP at reboot time is at an unintended location. And results in Triple faults in our case. Though this error at reboot can be safely ignored in a VM environment, am not sure what the effect would be on a physical system. May be it will result in a triple fault and an eventual hardware reset thus masking this BUG in the kernel. This fix just makes sure that we reset that status flag after initialization is done. Fix paranoia about using BIOS quickboot mechanism. Make sure that we clear the "shutdown status flag" in the CMOS register after each CPU is brought up. This fixes a problem where the "shutdown status flag" may remain set when a CPU is brought up after booting. Signed-off-by: Alok N Kataria Signed-off-by: Dan Arai Signed-off-by: Ingo Molnar --- arch/x86/kernel/smpboot.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 21ad3f396a0..4517d1c01eb 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1001,6 +1001,11 @@ do_rest: /* mark "stuck" area as not stuck */ *((volatile unsigned long *)trampoline_base) = 0; + /* + * Cleanup possible dangling ends... + */ + smpboot_restore_warm_reset_vector(); + return boot_error; } @@ -1254,11 +1259,6 @@ void __init native_smp_prepare_boot_cpu(void) void __init native_smp_cpus_done(unsigned int max_cpus) { - /* - * Cleanup possible dangling ends... - */ - smpboot_restore_warm_reset_vector(); - Dprintk("Boot done.\n"); impress_friends(); -- 2.11.4.GIT