linux-kernel - Re: [PATCH] powerpc/sysfs: disable hotplug for the boot cpu

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Message-ID: <1371250417.21896.17.camel@pasglop>
Date:	Sat, 15 Jun 2013 08:53:37 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Zhao Chenhui <chenhui.zhao@...escale.com>
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/sysfs: disable hotplug for the boot cpu

On Thu, 2013-06-13 at 19:25 +0800, Zhao Chenhui wrote:
> Some multicore SoCs firstly boot up the cpu0 after warm reset.
> In some suspend/resume cases, SoC will do a warm reset when resuming.
> In order to ensure that the suspending and resuming is running
> on a same cpu, cpu0 should be the last cpu to suspend. Here, cpu0 is
> the boot_cpuid.

Well, so:

  - In any case, your patch will break pseries, so it's not acceptable.

  - Why does it have to absolutely resume from the same CPU it suspended
from ? Can't you have a little bit of code on the resuming CPU that
checks if it's not online, poke an online one and goes back to sleep ?

Cheers,
Ben.


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