Re: tip/master broken with x2apic and kexec

From: Yinghai Lu
Date: Tue Jul 13 2010 - 19:30:36 EST


On 07/13/2010 03:00 PM, H. Peter Anvin wrote:
> On 07/12/2010 07:59 PM, Yinghai Lu wrote:
>> tip/master:
>> system1: BIOS enabled x2apic, first kernel boot well, and when kexec second kernel will cause system instant reboot.
>>
>> system2: BIOS not enable x2apic, first kernel boot well and enable x2apic, and kexec second kernel well. but when kexec third kernel will case system instant reboot.
>>
>> linus' tree is ok.
>>
>> but for system2 if boot with nox2apic ,intr-remaping off, iommu off, the kexec loop test will pass.
>>
>> the problem looks start in recent two or three weeks.
>>
>> Any idea?
>>
>> bisecting will take a while, because the system post take a while everytime.
>>
>> Thanks
>>
>> Yinghai Lu
>
> OK, I found the bug... if you could test out the patch which will be
> sent out shortly I would very much appreciate it.

not sure if your patch is the offending one now.

kL: kernel from linus tree
kT1: kernel from tip
kT2: kernel from tip with reverting your patch

BIOS-->kL ---> kL ---> kL....always working
BIOS-->kT1 ---> kT1 ---> kT1 : between second one and third one system reset instant...
BIOS-->kT2 ---> kT2 ---> kT2 : between second one and third one system reset instant...

BIOS-->kL ---> kL ---> kL ---> then kT1 ---> kT1 .... always working
BIOS-->kL ---> kL ---> kL ---> then kT2 ---> kT2 .... always working

looks like first kernel and second one can not be kernel from tip.

Yinghai
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