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From: Michael Ellerman <mpe@ellerman.id.au>
To: linuxppc-dev@lists.ozlabs.org
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Tyrel Datwyler <tyreld@linux.vnet.ibm.com>,
	Pingfan Liu <kernelfans@gmail.com>,
	linux-pm@vger.kernel.org
Subject: Re: [PATCH 2/2] powerpc/cpu: post the event cpux add/remove instead of online/offline during hotplug
Date: Sat, 04 Aug 2018 12:48:46 +1000	[thread overview]
Message-ID: <87tvoag835.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <1533217359-11420-2-git-send-email-kernelfans@gmail.com>

Hi Pingfan,

Pingfan Liu <kernelfans@gmail.com> writes:
> Technically speaking, echo 1/0 > cpuX/online is only a subset of cpu
> hotplug/unplug, i.e. add/remove. The latter one includes the physical
> adding/removing of a cpu device. Some user space tools such as kexec-tools
> resort to the event add/remove to automatically rebuild dtb.
> If the dtb is not rebuilt correctly, we may hang on 2nd kernel due to
> lack the info of boot-cpu-hwid in dtb.

I notice you also sent a patch for ppc64_cpu to deal with CPUs being
removed rather than just offlined.

If I apply this patch then existing ppc64_cpu (without your other patch)
will break. Is that right?

cheers

WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <mpe@ellerman.id.au>
To: Pingfan Liu <kernelfans@gmail.com>, linuxppc-dev@lists.ozlabs.org
Cc: Pingfan Liu <kernelfans@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Tyrel Datwyler <tyreld@linux.vnet.ibm.com>,
	linux-pm@vger.kernel.org
Subject: Re: [PATCH 2/2] powerpc/cpu: post the event cpux add/remove instead of online/offline during hotplug
Date: Sat, 04 Aug 2018 12:48:46 +1000	[thread overview]
Message-ID: <87tvoag835.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <1533217359-11420-2-git-send-email-kernelfans@gmail.com>

Hi Pingfan,

Pingfan Liu <kernelfans@gmail.com> writes:
> Technically speaking, echo 1/0 > cpuX/online is only a subset of cpu
> hotplug/unplug, i.e. add/remove. The latter one includes the physical
> adding/removing of a cpu device. Some user space tools such as kexec-tools
> resort to the event add/remove to automatically rebuild dtb.
> If the dtb is not rebuilt correctly, we may hang on 2nd kernel due to
> lack the info of boot-cpu-hwid in dtb.

I notice you also sent a patch for ppc64_cpu to deal with CPUs being
removed rather than just offlined.

If I apply this patch then existing ppc64_cpu (without your other patch)
will break. Is that right?

cheers

  parent reply	other threads:[~2018-08-04  2:48 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-02 13:42 [PATCH 1/2] powerpc/cpuidle: dynamically register/unregister cpuidle_device during hotplug Pingfan Liu
2018-08-02 13:42 ` Pingfan Liu
2018-08-02 13:42 ` [PATCH 2/2] powerpc/cpu: post the event cpux add/remove instead of online/offline " Pingfan Liu
2018-08-02 13:42   ` Pingfan Liu
2018-08-03 17:09   ` kbuild test robot
2018-08-03 17:09     ` kbuild test robot
2018-08-04  2:48   ` Michael Ellerman [this message]
2018-08-04  2:48     ` Michael Ellerman
2018-08-05  2:52     ` Pingfan Liu
2018-08-05  2:52       ` Pingfan Liu

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