From: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Sebastian Frias <sf84@laposte.net>,
linux-pm <linux-pm@vger.kernel.org>,
Thibaud Cornic <thibaud_cornic@sigmadesigns.com>,
Mason <slash.tmp@free.fr>, arm-soc <arm@kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v3 1/2] ARM: tango: add HOTPLUG_CPU support
Date: Wed, 29 Jun 2016 14:28:23 +0200 [thread overview]
Message-ID: <5773BEE7.4080501@sigmadesigns.com> (raw)
In-Reply-To: <577294E2.5030405@arm.com>
On 28/06/2016 17:16, Robin Murphy wrote:
> On 28/06/16 16:04, Marc Gonzalez wrote:
>
>> On 28/06/2016 14:30, Robin Murphy wrote:
>>
>>> Does the firmware guarantee that this will succeed (or at least report
>>> success) in finite time, regardless of how messed up the system might
>>> be? I'd imagine this should probably have either a timeout or a comment
>>> clarifying why it doesn't need a timeout.
>>
>> Good point.
>>
>> The FW allows only one thread at a time. If a thread is wedged inside
>> the FW, no other thread can use the FW. In that situation, cpu0 would
>> remain stuck inside tango_cpu_kill().
>>
>> Note, that if tango_cpu_kill() starts failing, then secondary cores
>> will remain "zombies". So the system is mostly hosed anyway...
>> Only cpu0 will be available.
>
> Indeed; my thought was that if CPU1 somehow ends up wedged such that
> tango_aux_core_die() never completes, then CPU0 eventually timing out
> and being able to limp through a clean(ish) reboot is probably
> preferable to spinning in cpu_kill() forever.
I have sent an updated patch addressing your comment.
Thanks for flagging the issue.
Regards.
next prev parent reply other threads:[~2016-06-29 12:28 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <57726597.8030501@sigmadesigns.com>
2016-06-28 11:59 ` [PATCH v3 1/2] ARM: tango: add HOTPLUG_CPU support Marc Gonzalez
2016-06-28 12:30 ` Robin Murphy
2016-06-28 15:04 ` Marc Gonzalez
2016-06-28 15:16 ` Robin Murphy
2016-06-29 12:28 ` Marc Gonzalez [this message]
2016-06-29 12:21 ` [PATCH v4 " Marc Gonzalez
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