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From: James Bottomley <James.Bottomley@suse.de>
To: "Ahmed S. Darwish" <darwish.07@gmail.com>
Cc: "Ingo Molnar" <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.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 11:02:35 -0500	[thread overview]
Message-ID: <1295971355.4955.104.camel@mulgrave.site> (raw)
In-Reply-To: <20110125153649.GA11386@laptop>

On Tue, 2011-01-25 at 17:36 +0200, Ahmed S. Darwish wrote:
> The complete __roadblock__ I'm currently facing though is restoring the disk
> controllers to the state originally setup by the BIOS Power-on self-test (POST).
> I hope such re-initialization is even technically feasible.
> 
> Without such re-initialization, we'll just be risking the BIOS code exploding.
> That was the case in the 5-minute hang described in the cover sheet (PATCH #0).

So this is the bit that's not really technically feasible.  BIOS tends
to run storage devices in a very primitive way (so it takes basic
settings, for example and sets the device up for one particular channel
of access).  When preparing the device for an operating system, we have
to blow away all the bios stuff and put it into a more generally
performant mode (this isn't just the storage per se, it's also the
interrupt and routing).  Unfortunately, currently, we don't bother to
save the settings the BIOS was using, so there's no way to reinitialise
the device back to bios without an effective reboot.  Most BIOS doesn't
seem to contain storage re-POST code that's usable (it's all embedded in
the boot sequence).

James



  reply	other threads:[~2011-01-25 16:02 UTC|newest]

Thread overview: 75+ 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
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 [this message]
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]   ` <AANLkTinU0KYiCd4p=z+=ojbkeEoT2G+CAYvdRU02KJEn-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-01-26 12:49     ` Ahmed S. Darwish
2011-01-26 12:49       ` Ahmed S. Darwish
2011-01-26 12:58       ` Ingo Molnar
2011-01-26 12:58         ` Ingo Molnar
     [not found]         ` <20110126125813.GA26952-X9Un+BFzKDI@public.gmane.org>
2011-01-26 13:34           ` Ahmed S. Darwish
2011-01-26 13:34             ` Ahmed S. Darwish
2011-01-26 14:00             ` Ingo Molnar
2011-01-26 14:00               ` Ingo Molnar
     [not found]               ` <20110126140030.GB30064-X9Un+BFzKDI@public.gmane.org>
2011-01-27  4:35                 ` H. Peter Anvin
2011-01-27  4:35                   ` H. Peter Anvin
     [not found]                   ` <4D40F5FD.6090507-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
2011-01-27 11:41                     ` Ingo Molnar
2011-01-27 11:41                       ` Ingo Molnar
     [not found]                       ` <20110127114113.GB20279-X9Un+BFzKDI@public.gmane.org>
2011-01-27 15:47                         ` Eric W. Biederman
2011-01-27 15:47                           ` Eric W. Biederman
     [not found]                           ` <m1aaimxs9h.fsf-+imSwln9KH6u2/kzUuoCbdi2O/JbrIOy@public.gmane.org>
2011-01-27 16:12                             ` H. Peter Anvin
2011-01-27 16:12                               ` H. Peter Anvin
2011-01-26 23:07       ` Luck, Tony
2011-01-26 23:07         ` Luck, Tony
2011-01-26 23:07         ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon Luck, Tony
2011-01-26 23:07         ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic Luck, Tony
     [not found]         ` <987664A83D2D224EAE907B061CE93D53019438EABF-osO9UTpF0URqS6EAlXoojrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2011-01-26 23:16           ` Dave Jones
2011-01-26 23:16             ` Dave Jones
     [not found]             ` <20110126231620.GA14807-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2011-01-26 23:21               ` Luck, Tony
2011-01-26 23:21                 ` Luck, Tony
     [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
2011-01-27 18:35                           ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon Luck, Tony
2011-01-27 18:35                           ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic Luck, Tony
     [not found]                         ` <4D4197CB.9070201@zytor.com>
     [not found]                           ` <20110127162429.GB26437@elte.hu>
2011-01-27 18:56                             ` Luck, Tony
2011-01-27 18:56                               ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon Luck, Tony
2011-01-27 18:56                               ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic Luck, Tony
2011-01-27  1:09           ` Ahmed S. Darwish
2011-01-27  1:09             ` Ahmed S. Darwish
     [not found]       ` <20110127021338.GA20334@redhat.com>
     [not found]         ` <20110127021338.GA20334-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2011-01-27  3:33           ` Ahmed S. Darwish
2011-01-27  3:33             ` Ahmed S. Darwish
2011-01-27  4:44           ` H. Peter Anvin
2011-01-27  4:44             ` H. Peter Anvin
     [not found]             ` <4D40F81E.1030009-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>
2011-01-27  5:26               ` Ahmed S. Darwish
2011-01-27  5:26                 ` Ahmed S. Darwish
2011-01-27  7:51                 ` Eric W. Biederman
2011-01-27  7:51                   ` Eric W. Biederman
2011-02-02 11:13                   ` Ahmed S. Darwish
2011-02-02 11:13                     ` Ahmed S. Darwish
2011-02-02 11:13                     ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk Ahmed S. Darwish
2011-02-02 11:13                     ` [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon panic Ahmed S. Darwish

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