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From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Cc: Jack Steiner <steiner@sgi.com>,
	mingo@elte.hu, tglx@linutronix.de, lenb@kernel.org,
	linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC] - Mapping ACPI tables as CACHED
Date: Sat, 24 Jul 2010 01:45:32 +0100	[thread overview]
Message-ID: <20100724004532.GA9240@srcf.ucam.org> (raw)
In-Reply-To: <20100724001449.GA9618@khazad-dum.debian.net>

On Fri, Jul 23, 2010 at 09:14:50PM -0300, Henrique de Moraes Holschuh wrote:
> Well, as it was raised in this thread, ACPI tables are likely to be near RAM
> regions used for IPC with the firmware or SMBIOS, and we have no idea of the
> kind of crap that could happen if we enable caching on those areas.
> 
> OTOH, we *know* of systems that force us to copy the ACPI tables to regular
> RAM, otherwise, the utterly broken BIOS corrupts the ACPI tables after the
> kernel has loaded.
>
> Couldn't we simply always copy all tables to regular RAM and mark THAT as
> cacheable (since there will be no IPC regions in it)?  For the tables that
> are only used once, we can free the RAM later.

I think this is reasonable. There's an argument that we shouldn't cache 
operation regions that may be sitting next to the ACPI tables, but I 
can't see any problems being caused by copying the tables to RAM.

-- 
Matthew Garrett | mjg59@srcf.ucam.org

  reply	other threads:[~2010-07-24  0:45 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-22 15:22 [RFC] - Mapping ACPI tables as CACHED Jack Steiner
2010-07-22 15:52 ` Len Brown
2010-07-23 16:38   ` Jack Steiner
2010-07-23  1:46 ` ykzhao
2010-07-23  7:23   ` Ingo Molnar
2010-07-23 14:26     ` ykzhao
2010-08-17 14:45       ` Jack Steiner
2010-08-17 15:51       ` H. Peter Anvin
2010-08-17 14:42     ` Jack Steiner
2010-08-17 14:39   ` Jack Steiner
2010-07-24  0:14 ` Henrique de Moraes Holschuh
2010-07-24  0:45   ` Matthew Garrett [this message]
2010-07-24 12:26     ` Henrique de Moraes Holschuh
2010-08-17 14:49   ` Jack Steiner
2010-08-17 16:02     ` Linus Torvalds
2010-08-17 16:02       ` Linus Torvalds
2010-08-24 21:39   ` H. Peter Anvin
2010-08-26 17:17     ` [RFC - V2] " Jack Steiner
2010-08-26 18:08       ` H. Peter Anvin
2010-12-08 21:22         ` Jack Steiner
2010-12-09  1:27           ` H. Peter Anvin
2010-12-09  3:50             ` Jack Steiner
2010-12-09  6:12               ` Len Brown
2010-08-17 15:59 ` [RFC] " Jack Steiner
2010-08-26 17:47   ` Len Brown

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