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From: "H. Peter Anvin" <hpa@zytor.com>
To: Tejun Heo <tj@kernel.org>
Cc: "Ingo Molnar" <mingo@elte.hu>,
	"Ahmed S. Darwish" <darwish.07@gmail.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>, X86-ML <x86@kernel.org>,
	"Tony Luck" <tony.luck@intel.com>,
	"Dave Jones" <davej@redhat.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	"Randy Dunlap" <rdunlap@xenotime.net>,
	"Willy Tarreau" <wtarreau@hera.kernel.org>,
	"Willy Tarreau" <w@1wt.eu>,
	"Dirk Hohndel" <hohndel@infradead.org>,
	Dirk.Hohndel@intel.com, IDE-ML <linux-ide@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Peter Zijlstra" <a.p.zijlstra@chello.nl>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"Arjan van de Ven" <arjan@infradead.org>
Subject: Re: [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic
Date: Tue, 25 Jan 2011 09:33:18 -0800	[thread overview]
Message-ID: <4D3F095E.9000004@zytor.com> (raw)
In-Reply-To: <20110125150834.GD27510@htj.dyndns.org>

On 01/25/2011 07:08 AM, Tejun Heo wrote:
> 
> There are holes but writing to them without full knowledge of the
> configuration can be quite dangerous.  I don't think it would be
> possible to mass deploy it without manual configuration unless we
> specifically reserve (and maybe mark) it in the filesystem.
> 

Reserve and mark in the filesystem is relatively straightforward, except
for btrfs, which doesn't have support for reserved extents.  This is a
bit of a shortcoming in btrfs.

>> All in one, a very intriguing idea IMO, and the hardest bits
>> (lowlevel x86 transition) is all implemented already.

Lowlevel x86 transition is not at all the hardest part.  It's
detail-oriented but well defined (and, I might add, incompletely
implemented -- 64 bits only, not using facilities we already have); the
*hard* part, and I mean harder by orders of magnitude, is to get the
BIOS to behave sanely without an intervening reboot, *AND* not trash
your data, ever.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.


  reply	other threads:[~2011-01-25 17:37 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-25 13:47 [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic Ahmed S. Darwish
2011-01-25 13:51 ` [PATCH -next 1/2][RFC] x86: Saveoops: Switch to real-mode and call BIOS Ahmed S. Darwish
2011-01-25 17:26   ` H. Peter Anvin
2011-01-25 13:53 ` [PATCH -next 2/2][RFC] x86: Saveoops: Reserve low memory and register code Ahmed S. Darwish
2011-01-25 17:29   ` H. Peter Anvin
2011-01-26  9:04     ` Ahmed S. Darwish
2011-01-25 14:09 ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic Ingo Molnar
2011-01-25 15:08   ` Tejun Heo
2011-01-25 17:33     ` H. Peter Anvin [this message]
2011-01-26 11:44       ` Ahmed S. Darwish
2011-02-03 14:36     ` Pavel Machek
2011-02-03 15:28       ` H. Peter Anvin
2011-02-03 17:57         ` Ingo Molnar
2011-02-03 21:07           ` H. Peter Anvin
2011-01-25 15:36   ` Ahmed S. Darwish
2011-01-25 16:02     ` James Bottomley
2011-01-25 17:05       ` Ahmed S. Darwish
2011-01-25 17:20         ` James Bottomley
2011-01-25 22:10         ` Mark Lord
2011-01-25 22:16           ` Randy Dunlap
2011-01-25 22:45             ` Jeff Garzik
2011-01-25 22:58               ` H. Peter Anvin
2011-01-26  0:26                 ` Jeff Garzik
2011-01-31  2:59                 ` Rusty Russell
2011-01-31 10:45                   ` Ingo Molnar
2011-01-25 17:32     ` Tony Luck
2011-01-25 17:36       ` H. Peter Anvin
2011-01-25 19:04       ` Jeff Garzik
2011-01-25 14:49 ` Tejun Heo
2011-01-28  7:59   ` Jan Ceuleers
2011-01-25 20:25 ` Linus Torvalds
     [not found]   ` <20110126124954.GC24527@laptop>
2011-01-26 23:07     ` Luck, Tony
     [not found]       ` <20110126231620.GA14807@redhat.com>
     [not found]         ` <987664A83D2D224EAE907B061CE93D53019438EB02@orsmsx505.amr.corp.intel.com>
     [not found]           ` <20110126233033.GB14807@redhat.com>
     [not found]             ` <987664A83D2D224EAE907B061CE93D53019438EBB6@orsmsx505.amr.corp.intel.com>
     [not found]               ` <4D40F7F1.3020509@zytor.com>
     [not found]                 ` <20110127120039.GD20279@elte.hu>
2011-01-27 18:35                   ` Luck, Tony
     [not found]                   ` <4D4197CB.9070201@zytor.com>
     [not found]                     ` <20110127162429.GB26437@elte.hu>
2011-01-27 18:56                       ` Luck, Tony
     [not found]     ` <20110127021338.GA20334@redhat.com>
     [not found]       ` <4D40F81E.1030009@zytor.com>
     [not found]         ` <20110127052639.GA16289@laptop>
     [not found]           ` <m1sjweyeax.fsf@fess.ebiederm.org>
2011-02-02 11:13             ` Ahmed S. Darwish

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