Re: [PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if invoked from disable_nonboot_cpus

From	James Morse <james.morse@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if invoked from disable_nonboot_cpus
Date	2016-07-07 10:50 +0200
Message-ID	<rSdaq-4y2-55@gated-at.bofh.it> (permalink)
References	<rOXbQ-4Tg-31@gated-at.bofh.it> <rS5mx-7SX-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi Rafael,

On 07/07/16 01:33, Rafael J. Wysocki wrote:
> Below is my sort of version of this (untested) and I did it this way, because
> the issue is specific to resume from hibernation (the workaround need not be
> applied anywhere else) and the hibernate_resume_nonboot_cpu_disable() thing may
> be useful to arm64 too if I'm not mistaken (James?).

Yes, we will always need to do something extra (based on data in the
arch_hibernation_header) to resume if CPU0 was offline, or kexec meant we no
longer know which CPU the firmware will boot us on.

> Actually, if arm64 uses it too, the __weak implementation can be dropped,
> because it will be possible to make it depend on ARCH_HIBERNATION_HEADER
> (x86 and arm64 are the only users of that).

Heh, I avoided that as it felt too much like a hack!

Thanks,

James

Thread

[PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if invoked from disable_nonboot_cpus Chen Yu <yu.c.chen@intel.com> - 2016-06-28 11:10 +0200
  Re: [PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if invoked from disable_nonboot_cpus "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-07-07 02:30 +0200
    RE: [PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if  invoked from disable_nonboot_cpus "Chen, Yu C" <yu.c.chen@intel.com> - 2016-07-07 05:00 +0200
      Re: [PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if invoked  from disable_nonboot_cpus James Morse <james.morse@arm.com> - 2016-07-07 18:10 +0200
    Re: [PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if invoked  from disable_nonboot_cpus James Morse <james.morse@arm.com> - 2016-07-07 10:50 +0200
      Re: [PATCH][RFC v3] x86, hotplug: Use hlt instead of mwait if invoked from disable_nonboot_cpus "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-07-07 14:30 +0200

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