linux-kernel - Re: [Xen-devel] [PATCH] xen/arm: disable cpuidle when linux is running as dom0

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Message-ID: <CAPnVf8xuQJpXv+D8QNqhdz=Pm8rvbWA-U0T-ZdC3Mye-KeLdGA@mail.gmail.com>
Date:	Thu, 18 Jul 2013 18:20:52 +0100
From:	Julien Grall <julien.grall@...aro.org>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Ian Campbell <ian.campbell@...rix.com>,
	Patch Tracking <patches@...aro.org>,
	linux-kernel@...r.kernel.org,
	"xen-devel@...ts.xen.org" <xen-devel@...ts.xen.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [Xen-devel] [PATCH] xen/arm: disable cpuidle when linux is
 running as dom0

On 17 July 2013 14:28, Stefano Stabellini
<stefano.stabellini@...citrix.com> wrote:
> On Mon, 15 Jul 2013, Konrad Rzeszutek Wilk wrote:
>> On Mon, Jul 15, 2013 at 03:21:41PM +0100, Julien Grall wrote:
>> > When linux is running as dom0, Xen doesn't show the physical cpu but a
>> > virtual CPU.
>> > On some ARM SOC (for instance the exynos 5250), linux registers callbacks
>> > for cpuidle. When these callbacks are called, they will modify
>> > directly the physical cpu not the virtual one.
>> It can impact the whole board
>> > instead of dom0.
>
> Certainly this is something that should be fixed at the hypervisor level
> too. However I agree that Linux should try to avoid doing that when
> running on Xen.
>
>
>
>> Should you also call disable_cpufreq() ?
>
> Sounds like a good idea.
> Julien, could you add that to this patch?

I have checked with both the Arndale and Versatile Express without any issue.
I will resend this patch with disable_cpufreq().

-- 
Julien Grall
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