On Sun, 9 Aug 2015, Laura Abbott wrote:
> (missed the LKML cc apologies for the noise)
>
> On 08/09/2015 06:51 AM, Laura Abbott wrote:
> > Hi,
> >
> > We received a report[1] of an early boot crash. The reporter had difficulty
> > getting a full
> > kernel log to view and only had a screenshot which showed a crash in
> > native_apic_mem_read
> > (full screenshot available at the bugzilla along with dmesg from working
> > kernel)
> >
> > Bisection identified the following commit:
> >
> > commit 659006bf3ae37a08706907ce1a36ddf57c9131d2
> > Author: Thomas Gleixner <t...@linutronix.de>
> > Date: Thu Jan 15 21:22:26 2015 +0000
> >
> > x86/x2apic: Split enable and setup function
> >
> > enable_x2apic() is a convoluted unreadable mess because it is used for
> > both enablement in early boot and for setup in cpu_init().
> >
> > Split the code into x2apic_enable() for enablement and x2apic_setup()
> > for setup of (secondary cpus). Make use of the new state tracking to
> > simplify the logic.
> >
> > Signed-off-by: Thomas Gleixner <t...@linutronix.de>
> > Cc: Jiang Liu <jiang....@linux.intel.com>
> > Cc: Joerg Roedel <j...@8bytes.org>
> > Cc: Tony Luck <tony.l...@intel.com>
> > Cc: Borislav Petkov <b...@alien8.de>
> > Link: http://lkml.kernel.org/r/20150115211703.129287...@linutronix.de
> > Signed-off-by: Thomas Gleixner <t...@linutronix.de>
> >
> > The report indicates that if local x2apic is disabled in the BIOS the kernel
> > boots.
> >
> > Any ideas?
Does the patch below fix the issue?
Thanks,
tglx
-------------------->
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index dcb52850a28f..339cf4fc4ca9 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1424,7 +1424,7 @@ static inline void __x2apic_disable(void)
{
u64 msr;
- if (cpu_has_apic)
+ if (!cpu_has_apic)
return;
rdmsrl(MSR_IA32_APICBASE, msr);
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