[PATCH v8 0/4] improvements to the nmi_backtrace code

Daniel Thompson daniel.thompson at linaro.org
Thu Aug 18 08:46:05 PDT 2016

On 16/08/16 20:50, Chris Metcalf wrote:
> This is a rebase of the series onto v4.8-rc2, plus some changes from
> various reviewers.
> From the version 1 cover letter:
>   This patch series modifies the trigger_xxx_backtrace() NMI-based
>   remote backtracing code to make it more flexible, and makes a few
>   small improvements along the way.
>   The motivation comes from the task isolation code, where there are
>   scenarios where we want to be able to diagnose a case where some cpu
>   is about to interrupt a task-isolated cpu.  It can be helpful to
>   see both where the interrupting cpu is, and also an approximation
>   of where the cpu that is being interrupted is.  The nmi_backtrace
>   framework allows us to discover the stack of the interrupted cpu.
> I've tested that the change works as desired on tile, and build-tested
> x86, arm, mips, and sparc64.  For x86 I confirmed that the generic
> cpuidle stuff as well as the architecture-specific routines are in the
> new cpuidle section.  For arm, mips, and sparc I just build-tested it
> and made sure the generic cpuidle routines were in the new cpuidle
> section, but I didn't attempt to figure out which the
> platform-specific idle routines might be.  That might be more usefully
> done by someone with platform experience in follow-up patches.

You can add runtime testing on arm to the list (I didn't try to exploit 
the new one-line-for-idle feature but there were no regressions). All 

Tested-by: Daniel Thompson <daniel.thompson at linaro.org>


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