From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Fan Rong <cinifr@gmail.com>
Cc: coosty@163.com, daniel.lezcano@linaro.org,
linux@arm.linux.org.uk, tglx@linutronix.de,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, mark.rutland@arm.com,
pawel.moll@arm.com, rob.herring@calxeda.com,
linux-sunxi@googlegroups.com
Subject: Re: [Add SMP support for Allwinner A20: PATCH V5 3/3] Add arch count timer node in dts for Allwinner A20(sunxi 7i).
Date: Wed, 23 Oct 2013 12:28:09 +0100 [thread overview]
Message-ID: <20131023112809.GX3041@lukather> (raw)
In-Reply-To: <1382027827-10080-4-git-send-email-cinifr@gmail.com>
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On Fri, Oct 18, 2013 at 12:37:07AM +0800, Fan Rong wrote:
> Linux kernel usually use virtual arch timer for smp cpu tick. But the
> arch timer register VCTOFF normally is very different between the two
> cpus in A20 afer hardware reset, so SMP Cpus will see different time
> tick. It will cause kernel crash currently. You have two choices to
> fix it: 1 Simpley use physical arch timer, 2 Set VCTOFF to same value
> for each cpu in bootloader. The first choice will cause some other
> problem for kernel, especially for KVM, guest OS want to use virtual
> arch timer. So the second choice is perfect. So if you want to use
> arch timer for smp cpu tick, you must ensure you bootload have set
> same VCTOFF for all cpus.
>
Is your patchset working without that last patch?
I'm not really wanting to apply it right now.
It relies on a bootloader behaviour that is not implemented by any
bootloader we have openly available right now. I will apply it after
it's been merged in at least u-boot-sunxi.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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next prev parent reply other threads:[~2013-10-23 11:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-17 16:37 [Add SMP support for Allwinner A20: PATCH V5 0/3] Fan Rong
2013-10-17 16:37 ` [Add SMP support for Allwinner A20: PATCH V5 1/3] Add smp support for Allwinner A20(sunxi 7i) Fan Rong
2013-10-22 0:48 ` cinifr
2013-10-25 10:25 ` Maxime Ripard
2013-10-17 16:37 ` [Add SMP support for Allwinner A20: PATCH V5 2/3] Add cpuconfig nodes in dts for smp configure Fan Rong
2013-10-17 16:37 ` [Add SMP support for Allwinner A20: PATCH V5 3/3] Add arch count timer node in dts for Allwinner A20(sunxi 7i) Fan Rong
2013-10-23 11:28 ` Maxime Ripard [this message]
2013-10-23 11:25 ` [Add SMP support for Allwinner A20: PATCH V5 0/3] Maxime Ripard
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