Re: [PATCH v4 0/3] x86, apic, kexec: Add disable_cpu_apic kernel parameter

[jerry.hoemann@hp.com]

On Wed, Oct 23, 2013 at 12:01:18AM +0900, HATAYAMA Daisuke wrote:
> This patch set is to allow kdump 2nd kernel to wake up multiple CPUs
> even if 1st kernel crashs on some AP, a continueing work from:
> 
>   [PATCH v3 0/2] x86, apic, kdump: Disable BSP if boot cpu is AP
>   https://lkml.org/lkml/2013/10/16/300.
> 
> In this version, basic design has changed. Now users need to figure
> out initial APIC ID of BSP in the 1st kernel and configures kernel
> parameter for the 2nd kernel manually using disable_cpu_apic kernel
> parameter to be newly introduced in this patch set. This design is
> more flexible than the previous version in that we no longer have to
> rely on ACPI/MP table to get initial APIC ID of BSP.
> 
> Sorry, this patch set have not include in-source documentation
> requested by Borislav Petkov yet, but I'll post it later separately,
> which would be better to focus on documentation reviewing.
> 
> ChangeLog
> 
> v3 => v4)
> 
> - Rebased on top of v3.12-rc6
> 
> - Basic design has been changed. Now users need to figure out initial
>   APIC ID of BSP in the 1st kernel and configures kernel parameter for
>   the 2nd kernel manually using disable_cpu_apic kernel parameter to
>   be newly introduced in this patch set. This design is more flexible
>   than the previous version in that we no longer have to rely on
>   ACPI/MP table to get initial APIC ID of BSP.
> 


Daisuke,

I have back ported version 4 of this patch to both a 2.6.32 and 3.0.80
based kernels and distros and tested on a prototype system.  I have
previously test version 1 & 3 as well.)

The systems are configured to boot the capture kernel 8-way parallel.
However, I am running makedumpfile single threaded.

Panic is induced via "echo c > /proc/sysrq-trigger".  This is done
under various system loads and on random cpus.  I have done over a
thousand dumps total during this testing.

I have seen no issues w/ the 3.0.80 dump testing on our proto.

On the 2.6.32 testing on our proto, i have hit a low probability (< 5%)
chance of the capture suffering a soft lockup hang during
"Switching to clocksource hpet."  I have not RCA'd this yet.
Note, I have seen this issue on earlier version of the patch, so
it is not specific to this version.

I then tested the 2.6.32 port on a dl380.  This worked without issue.

Note, I have seen no issues related to this patch on our proto when
booting the capture with a single processor.

While I am still pursuing the issue of the 2.6.32 kernel on our proto,
I believe this patch is good and should be accepted.




thanks

Jerry

-- 

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Jerry Hoemann            Software Engineer              Hewlett-Packard/MODL

3404 E Harmony Rd. MS 57                        phone:  (970) 898-1022
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                                                email:  jerry.hoemann@hp.com
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