From: Will Deacon <will.deacon@arm.com>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Stephen Warren <swarren@nvidia.com>,
Peter De Schrijver <pdeschrijver@nvidia.com>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
Eric Biederman <ebiederm@xmission.com>,
Joseph Lo <josephl@nvidia.com>,
"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] kexec: disable non-boot CPUs
Date: Sun, 23 Dec 2012 11:06:02 +0000 [thread overview]
Message-ID: <20121223110602.GA16237@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <50D371E2.1030807@wwwdotorg.org>
On Thu, Dec 20, 2012 at 08:15:30PM +0000, Stephen Warren wrote:
> On 12/20/2012 10:59 AM, Stephen Warren wrote:
> > On 12/20/2012 10:36 AM, Will Deacon wrote:
> >> I think you're better off using what we currently have and hanging your code
> >> off platform_cpu_kill.
> >
> > OK, I'll look into that. Joseph Lo just posted patches to implement
> > cpu_kill() on Tegra, which was needed to fix some issues in our hotplug
> > code anyway. Perhaps that will remove the need for any other changes...
>
> Will,
Hi Stephen,
> I just remembered one other advantage of disable_nonboot_cpus(); it
> always makes the kexec happen on the boot CPU. Without this, I believe
> it's random whether CPU0 or CPU1 performs the kexec. I suspect it's most
> likely to work if we can always kexec on the boot CPU rather than a
> random CPU?
It will be the same CPU as the one which made the kexec system call. If you
need to invoke this from a specific CPU, you currently have to do this in
userspace using something like the `taskset' utility. Linux can actually
boot on any physical CPU for ARM now (thanks to the logical map) but most
platforms have restrictions related to secure firmware.
Will
_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec
WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
To: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Cc: Joseph Lo <josephl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
Peter De Schrijver
<pdeschrijver-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
"linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Stephen Warren <swarren-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
"kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
Eric Biederman <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>,
"linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>
Subject: Re: [PATCH] kexec: disable non-boot CPUs
Date: Sun, 23 Dec 2012 11:06:02 +0000 [thread overview]
Message-ID: <20121223110602.GA16237@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <50D371E2.1030807-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
On Thu, Dec 20, 2012 at 08:15:30PM +0000, Stephen Warren wrote:
> On 12/20/2012 10:59 AM, Stephen Warren wrote:
> > On 12/20/2012 10:36 AM, Will Deacon wrote:
> >> I think you're better off using what we currently have and hanging your code
> >> off platform_cpu_kill.
> >
> > OK, I'll look into that. Joseph Lo just posted patches to implement
> > cpu_kill() on Tegra, which was needed to fix some issues in our hotplug
> > code anyway. Perhaps that will remove the need for any other changes...
>
> Will,
Hi Stephen,
> I just remembered one other advantage of disable_nonboot_cpus(); it
> always makes the kexec happen on the boot CPU. Without this, I believe
> it's random whether CPU0 or CPU1 performs the kexec. I suspect it's most
> likely to work if we can always kexec on the boot CPU rather than a
> random CPU?
It will be the same CPU as the one which made the kexec system call. If you
need to invoke this from a specific CPU, you currently have to do this in
userspace using something like the `taskset' utility. Linux can actually
boot on any physical CPU for ARM now (thanks to the logical map) but most
platforms have restrictions related to secure firmware.
Will
WARNING: multiple messages have this Message-ID (diff)
From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] kexec: disable non-boot CPUs
Date: Sun, 23 Dec 2012 11:06:02 +0000 [thread overview]
Message-ID: <20121223110602.GA16237@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <50D371E2.1030807@wwwdotorg.org>
On Thu, Dec 20, 2012 at 08:15:30PM +0000, Stephen Warren wrote:
> On 12/20/2012 10:59 AM, Stephen Warren wrote:
> > On 12/20/2012 10:36 AM, Will Deacon wrote:
> >> I think you're better off using what we currently have and hanging your code
> >> off platform_cpu_kill.
> >
> > OK, I'll look into that. Joseph Lo just posted patches to implement
> > cpu_kill() on Tegra, which was needed to fix some issues in our hotplug
> > code anyway. Perhaps that will remove the need for any other changes...
>
> Will,
Hi Stephen,
> I just remembered one other advantage of disable_nonboot_cpus(); it
> always makes the kexec happen on the boot CPU. Without this, I believe
> it's random whether CPU0 or CPU1 performs the kexec. I suspect it's most
> likely to work if we can always kexec on the boot CPU rather than a
> random CPU?
It will be the same CPU as the one which made the kexec system call. If you
need to invoke this from a specific CPU, you currently have to do this in
userspace using something like the `taskset' utility. Linux can actually
boot on any physical CPU for ARM now (thanks to the logical map) but most
platforms have restrictions related to secure firmware.
Will
next prev parent reply other threads:[~2012-12-23 11:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-19 23:44 [PATCH] kexec: disable non-boot CPUs Stephen Warren
2012-12-19 23:44 ` Stephen Warren
2012-12-19 23:44 ` Stephen Warren
2012-12-19 23:55 ` Eric W. Biederman
2012-12-19 23:55 ` Eric W. Biederman
2012-12-19 23:55 ` Eric W. Biederman
2012-12-20 10:49 ` Will Deacon
2012-12-20 10:49 ` Will Deacon
2012-12-20 10:49 ` Will Deacon
2012-12-20 17:21 ` Stephen Warren
2012-12-20 17:21 ` Stephen Warren
2012-12-20 17:21 ` Stephen Warren
2012-12-20 17:36 ` Will Deacon
2012-12-20 17:36 ` Will Deacon
2012-12-20 17:36 ` Will Deacon
2012-12-20 17:59 ` Stephen Warren
2012-12-20 17:59 ` Stephen Warren
2012-12-20 17:59 ` Stephen Warren
2012-12-20 20:15 ` Stephen Warren
2012-12-20 20:15 ` Stephen Warren
2012-12-20 20:15 ` Stephen Warren
2012-12-23 11:06 ` Will Deacon [this message]
2012-12-23 11:06 ` Will Deacon
2012-12-23 11:06 ` Will Deacon
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