Date: Thu, 6 Nov 2008 10:17:51 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>, Dave Hansen <dave@linux.vnet.ibm.com>,
       Yasunori Goto <y-goto@jp.fujitsu.com>,
       Nigel Cunningham <ncunningham@crca.org.au>,
       Matt Tolentino <matthew.e.tolentino@intel.com>, linux-pm@lists.osdl.org,
       Dave Hansen <haveblue@us.ibm.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, pavel@suse.cz, Mel Gorman <mel@skynet.ie>,
       Andy Whitcroft <apw@shadowen.org>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [linux-pm] [PATCH] hibernation should work ok with memory
 hotplug
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On Thu, 6 Nov 2008 09:14:41 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> Ok, please consider "when memory hotplug happens." 
> 
> In general, it happens when
>   1. memory is inserted to slot.
>   2. the firmware notifes the system to enable already inserted memory.
> 
> To trigger "1", you have to open cover of server/pc. Do you open pc while the system
> starts hibernation ? for usual people, no.
> 
> To trigger "2", the user have special console to tell firmware "enable this memory".
> Such firmware console or users have to know "the system works well." And, more important,
> when the system is suspended, the firmware can't do hotplug because the kernel is sleeping.
> So, such firmware console or operator have to know the system status.
> 
> Am I missing some ? Current linux can know PCI/USB hotplug while the system is suspended ?
> 
*OFFTOPIC*

I hear following answer from my friend.

  - hibernate the system
	=> plug USB memory
		=> wake up the system
			=> panic.
  - hibernate the system
	=> unplug USB memory
		=> wake up the sytem
			=> panic.

Thanks,
-Kame

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