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From: Ingo Molnar <mingo@kernel.org>
To: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Keerthy <a0393675@ti.com>, Keerthy <j-keerthy@ti.com>,
	linux-kernel@vger.kernel.org, edubezval@gmail.com,
	grygorii.strashko@ti.com, nm@ti.com, linux-pm@vger.kernel.org,
	linux-omap@vger.kernel.org, joel@jms.id.au,
	akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org,
	peterz@infradead.org, dyoung@redhat.com, josh@joshtriplett.org,
	mpe@ellerman.id.au, Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [PATCH v2] reboot: Backup orderly_poweroff
Date: Fri, 15 Jan 2016 11:14:59 +0100	[thread overview]
Message-ID: <20160115101459.GB23349@gmail.com> (raw)
In-Reply-To: <20160114132527.575e0f20@lxorguk.ukuu.org.uk>


* One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> wrote:

> > If kernel_power_off() is called then the system should power off. No ifs and 
> > whens.
> 
> Even if it doesn't the watchdog should kill it. 
> 
> That is broken on some platforms on the watchdog side as the
> watchdog shuts down during our power off callbacks - because the system
> firmware is too stupid to reset the watchdog as it powers back up (so
> keeps rebooting).
> 
> If you watchdog and firmware function properly you shouldn't even have to
> care if you crash during the kernel power off.

That's a good point as well - if the system is 'stuck' for some notion of stuck, 
then watchdog drivers can help.

Here it's unclear whether user-space even called the sys_reboot() system call.

Thanks,

	Ingo

WARNING: multiple messages have this Message-ID (diff)
From: mingo@kernel.org (Ingo Molnar)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] reboot: Backup orderly_poweroff
Date: Fri, 15 Jan 2016 11:14:59 +0100	[thread overview]
Message-ID: <20160115101459.GB23349@gmail.com> (raw)
In-Reply-To: <20160114132527.575e0f20@lxorguk.ukuu.org.uk>


* One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk> wrote:

> > If kernel_power_off() is called then the system should power off. No ifs and 
> > whens.
> 
> Even if it doesn't the watchdog should kill it. 
> 
> That is broken on some platforms on the watchdog side as the
> watchdog shuts down during our power off callbacks - because the system
> firmware is too stupid to reset the watchdog as it powers back up (so
> keeps rebooting).
> 
> If you watchdog and firmware function properly you shouldn't even have to
> care if you crash during the kernel power off.

That's a good point as well - if the system is 'stuck' for some notion of stuck, 
then watchdog drivers can help.

Here it's unclear whether user-space even called the sys_reboot() system call.

Thanks,

	Ingo

  reply	other threads:[~2016-01-15 10:14 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-13 12:33 [PATCH v2] reboot: Backup orderly_poweroff Keerthy
2016-01-13 12:33 ` Keerthy
2016-01-13 12:33 ` Keerthy
2016-01-14  9:05 ` Ingo Molnar
2016-01-14  9:05   ` Ingo Molnar
2016-01-14  9:18   ` Keerthy
2016-01-14  9:18     ` Keerthy
2016-01-14  9:18     ` Keerthy
2016-01-14 10:09     ` Ingo Molnar
2016-01-14 10:09       ` Ingo Molnar
2016-01-14 10:42       ` Keerthy
2016-01-14 10:42         ` Keerthy
2016-01-14 10:42         ` Keerthy
2016-01-14 11:23         ` Ingo Molnar
2016-01-14 11:23           ` Ingo Molnar
2016-01-14 13:25           ` One Thousand Gnomes
2016-01-14 13:25             ` One Thousand Gnomes
2016-01-15 10:14             ` Ingo Molnar [this message]
2016-01-15 10:14               ` Ingo Molnar
2016-01-15 13:29               ` Grygorii Strashko
2016-01-15 13:29                 ` Grygorii Strashko
2016-01-15 13:29                 ` Grygorii Strashko
2016-01-15 14:12                 ` Russell King - ARM Linux
2016-01-15 14:12                   ` Russell King - ARM Linux
2016-01-19  9:06                 ` Ingo Molnar
2016-01-19  9:06                   ` Ingo Molnar
2016-01-19 10:32                   ` Keerthy
2016-01-19 10:32                     ` Keerthy
2016-01-19 10:32                     ` Keerthy
2016-01-14 14:22           ` Russell King - ARM Linux
2016-01-14 14:22             ` Russell King - ARM Linux
2016-01-15 10:13             ` Ingo Molnar
2016-01-15 10:13               ` Ingo Molnar
2016-01-15 11:05               ` Russell King - ARM Linux
2016-01-15 11:05                 ` Russell King - ARM Linux

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