Message-ID: <556E3F03.5040008@hitachi.com>
Date: Wed, 03 Jun 2015 08:40:51 +0900
From: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com>
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To: Russell King - ARM Linux <linux@arm.linux.org.uk>
CC: dinguyen@opensource.altera.com, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] ARM: socfpga: add smp_ops.cpu_kill to make kexec/kdump
 available
References: <20150529053844.31162.43927.stgit@arietta> <20150529083339.GG2067@n2100.arm.linux.org.uk> <XNM1$3$0$0$$3$3$3$A$0000051U556d3fe3@hitachi.com> <20150602083804.GX2067@n2100.arm.linux.org.uk>
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Hello, Russell,

On 2015/06/02 17:38, Russell King - ARM Linux wrote:
 > I wasn't thinking of SPIs and PPIs, but SGIs - the IPI interrupts coming
 > from the boot CPU.

All tasks in a CPU going offline are migrated to other CPUs(finally
CPU0) and the rq is marked with offline before the CPU entering WFI
loop. So IPI is not sent to the secondary CPU.

 > If you have a way to reset CPU0, why are you not using this for hotplug
 > when a CPU is hot-unplugged?

I think you mean "way to reset CPU1". If so, the reason is an increase
in power consumption in usual hotplug. This is discussed before between
Alan Tull and you. (https://lkml.org/lkml/2014/9/25/37)

Best regards,
Hiraku Toyooka
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