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Date: Tue, 25 Jan 2011 17:45:49 -0500
From: Jeff Garzik <jgarzik@pobox.com>
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To: Randy Dunlap <rdunlap@xenotime.net>
CC: Mark Lord <kernel@teksavvy.com>, "Ahmed S. Darwish" <darwish.07@gmail.com>,
        James Bottomley <James.Bottomley@suse.de>, Tejun Heo <tj@kernel.org>,
        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>,
        Willy Tarreau <wtarreau@hera.kernel.org>, Willy Tarreau <w@1wt.eu>,
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        Borislav Petkov <bp@alien8.de>, Arjan van de Ven <arjan@infradead.org>,
        Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH 0/2][concept RFC] x86: BIOS-save kernel log to disk upon
 panic
References: <20110125134748.GA10051@laptop> <20110125140948.GA26762@elte.hu> <20110125153649.GA11386@laptop> <1295971355.4955.104.camel@mulgrave.site> <20110125170522.GA16285@laptop> <4D3F4A69.7090702@teksavvy.com> <20110125141605.43963105.rdunlap@xenotime.net>
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On 01/25/2011 05:16 PM, Randy Dunlap wrote:
> On Tue, 25 Jan 2011 17:10:49 -0500 Mark Lord wrote:
>
>> On 11-01-25 12:05 PM, Ahmed S. Darwish wrote:
>>>
>>> My current x86 laptop includes the very common ATA PIIX controller.
>>
>>
>> ata_piix is just about ideal for this sort of thing.
>>
>> Except, don't use the BIOS to write the logs,
>> but rather code/use a very simple set of polling-PIO
>> functions to talk directly through the PIIX to the drive.
>>
>> Really really simple code to do that, and it would likely
>> work with anything ata-piix, and most other non-AHCI chipsets too.
>>
>> Not perfect, but probably good enough for a lot of scenarios.
>> The old hd.c driver shows how to read/write a sector at a time,
>> and that kind of code is easily converted to simply poll for completion.
>
> I don't know how/where to find it, but Rusty Russell had a version of this
> many, many years ago.

You beat me to the reply :)

http://lwn.net/Articles/9905/

but IIRC there were updates and improvements.