linux-kernel - Re: [PATCH] ARM: kexec: Relax SMP validation to improve DT compatibility

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Message-ID: <54EF560F.3070805@wwwdotorg.org>
Date:	Thu, 26 Feb 2015 10:21:19 -0700
From:	Stephen Warren <swarren@...dotorg.org>
To:	Geert Uytterhoeven <geert+renesas@...der.be>,
	Russell King <linux@....linux.org.uk>,
	Magnus Damm <magnus.damm@...il.com>,
	Stephen Warren <swarren@...dia.com>
CC:	linux-arm-kernel@...ts.infradead.org, linux-sh@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: kexec: Relax SMP validation to improve DT compatibility

On 02/26/2015 03:37 AM, Geert Uytterhoeven wrote:
> When trying to kexec into a new kernel on a platform where multiple CPU
> cores are present, but no SMP bringup code is available yet, the
> kexec_load system call fails with:
>
>      kexec_load failed: Invalid argument
>
> The SMP test added to machine_kexec_prepare() in commit 2103f6cba61a8b8b
> ("ARM: 7807/1: kexec: validate CPU hotplug support") wants to prohibit
> kexec on SMP platforms where it cannot disable secondary CPUs.
> However, this test is too strict: if the secondary CPUs couldn't be
> enabled in the first place, there's no need to disable them later at
> kexec time.  Hence skip the test in the absence of SMP bringup code.
>
> This allows to add all CPU cores to the DTS from the beginning, without
> having to implement SMP bringup first, improving DT compatibility.

Acked-by: Stephen Warren <swarren@...dia.com>
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