From: ebiederm@xmission.com (Eric W. Biederman)
To: "Yinghai Lu" <yhlu.kernel@gmail.com>
Cc: "Gabriel C" <nix.or.die@googlemail.com>,
"Andi Kleen" <andi@firstfloor.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Ingo Molnar" <mingo@elte.hu>, "H. Peter Anvin" <hpa@zytor.com>,
LKML <linux-kernel@vger.kernel.org>,
"Jesse Barnes" <jesse.barnes@intel.com>,
"Mika Fischer" <mika.fischer@zoopnet.de>,
balajirrao@gmail.com
Subject: Re: [PATCH] x86_32: trim memory by updating e820 v3
Date: Mon, 28 Apr 2008 11:07:59 -0700 [thread overview]
Message-ID: <m17ieh4zuo.fsf@frodo.ebiederm.org> (raw)
In-Reply-To: <86802c440804261805rc739f9as519213fecdc0cdff@mail.gmail.com> (Yinghai Lu's message of "Sat, 26 Apr 2008 18:05:39 -0700")
"Yinghai Lu" <yhlu.kernel@gmail.com> writes:
> On Sat, Apr 26, 2008 at 5:56 AM, Gabriel C <nix.or.die@googlemail.com> wrote:
> another continuous MTRR mapping.
>
> several months ago, we were talking about modifying MTRR. but Eric
> said that is not safe because acpi and smi...
I think it was Andi who spotted that originally, and yes I do think it
is a pretty horrific failure mode. Reprogramming the MTRRs requires
full knowledge of the hardware and what is going on that we don't
always have. PAT support has just been merged, and using that only
requires knowledge about the region whose attributes we intend to change.
So lets concentrate on PAT to solve contiguous MTRR region problems.
We can upgrade UC to WC with pat. As well as demote WB to UC or WC.
So for those regions we know about we should be in good shape.
In a slightly related vein. Trimming the memory we consider usable by
looking at MTRRs and if a region is not WB not considering it RAM
sounds like a very reasonable work around for one class of BIOS bugs.
Eric
next prev parent reply other threads:[~2008-04-28 18:08 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-20 4:45 [PATCH] x86: disable_mtrr_trim only need for x86_64 Yinghai Lu
2008-01-20 5:37 ` H. Peter Anvin
2008-01-20 6:55 ` Yinghai Lu
2008-01-20 8:17 ` [PATCH] x86_64: update e820 instead of updating end_pfn Yinghai Lu
2008-01-20 9:20 ` Ingo Molnar
2008-01-20 15:08 ` Andi Kleen
2008-01-21 5:40 ` [PATCH] x86_64: update e820 instead of updating end_pfn v2 Yinghai Lu
2008-01-21 5:44 ` [PATCH] x86_32: trim memory by updating e820 Yinghai Lu
2008-01-21 5:58 ` [PATCH] x86_64: update e820 instead of updating end_pfn v2 Andi Kleen
2008-01-21 6:05 ` Harvey Harrison
2008-01-21 6:08 ` Andi Kleen
2008-01-21 6:14 ` Li Zefan
2008-01-21 6:57 ` [PATCH] x86_64: check if Tom2 is enabled Yinghai Lu
2008-01-21 17:24 ` Cyrill Gorcunov
2008-01-21 17:39 ` H. Peter Anvin
2008-01-21 17:49 ` Cyrill Gorcunov
2008-01-21 18:03 ` Andi Kleen
2008-01-21 18:09 ` Cyrill Gorcunov
2008-01-21 18:15 ` H. Peter Anvin
2008-01-21 18:46 ` Andi Kleen
2008-01-21 0:00 ` [PATCH] x86_64: update e820 instead of updating end_pfn Yinghai Lu
[not found] ` <200801202255.02645.yinghai.lu@sun.com>
[not found] ` <200801202255.58642.yinghai.lu@sun.com>
2008-01-21 6:56 ` [PATCH] x86_32: trim memory by updating e820 v2 Yinghai Lu
2008-01-21 16:30 ` Jesse Barnes
2008-01-21 19:14 ` Justin Piszcz
2008-01-21 20:09 ` Yinghai Lu
2008-01-21 21:37 ` Justin Piszcz
2008-01-23 3:50 ` Yinghai Lu
2008-01-26 0:01 ` Justin Piszcz
2008-01-26 0:16 ` Yinghai Lu
2008-01-26 0:37 ` Justin Piszcz
2008-01-28 15:09 ` Ingo Molnar
2008-01-28 18:07 ` Justin Piszcz
2008-01-22 16:51 ` Ingo Molnar
2008-01-23 0:23 ` [PATCH] x86_32: trim memory by updating e820 v3 Yinghai Lu
2008-04-26 10:56 ` Andrew Morton
2008-04-26 12:56 ` Gabriel C
2008-04-27 1:05 ` Yinghai Lu
2008-04-28 18:07 ` Eric W. Biederman [this message]
2008-04-28 23:16 ` Yinghai Lu
2008-04-29 10:31 ` Ingo Molnar
2008-04-29 17:29 ` Eric W. Biederman
2008-04-29 18:40 ` Yinghai Lu
2008-04-29 19:19 ` Eric W. Biederman
2008-04-29 19:44 ` Yinghai Lu
2008-04-29 20:02 ` Eric W. Biederman
2008-04-28 6:44 ` Yinghai Lu
2008-04-28 9:18 ` Gabriel C
2008-04-28 9:34 ` Yinghai Lu
2008-04-28 9:54 ` Gabriel C
2008-04-28 10:03 ` Gabriel C
2008-04-28 10:07 ` Mika Fischer
2008-04-28 19:03 ` Yinghai Lu
2008-04-28 13:53 ` Ingo Molnar
2008-04-28 14:11 ` Mika Fischer
2008-04-28 14:24 ` Gabriel C
2008-04-28 19:06 ` Yinghai Lu
2008-04-28 19:38 ` Gabriel C
2008-04-28 20:45 ` Gabriel C
2008-04-28 21:19 ` Gabriel C
2008-04-28 22:03 ` Yinghai Lu
2008-04-28 22:56 ` Gabriel C
2008-04-28 23:23 ` Yinghai Lu
2008-04-29 1:05 ` Gabriel C
2008-04-29 2:41 ` Yinghai Lu
2008-04-29 10:34 ` Ingo Molnar
2008-04-29 10:42 ` Yinghai Lu
2008-04-28 19:08 ` Yinghai Lu
2008-04-28 19:46 ` Gabriel C
2008-04-28 14:15 ` Gabriel C
2008-04-28 16:09 ` Jesse Barnes
2008-04-28 16:31 ` Mika Fischer
2008-04-28 16:55 ` Jesse Barnes
2008-04-29 10:37 ` Ingo Molnar
2008-04-29 12:40 ` Andrew Morton
2008-04-29 15:52 ` Jesse Barnes
2008-04-29 22:03 ` [patch] PCI: export resource_wc in pci sysfs Ingo Molnar
2008-04-29 22:24 ` Andrew Morton
2008-04-27 0:57 ` [PATCH] x86_32: trim memory by updating e820 v3 Yinghai Lu
2008-04-27 8:21 ` Mika Fischer
2008-04-27 1:22 ` Yinghai Lu
2008-04-27 8:29 ` Mika Fischer
2008-04-28 6:50 ` Yinghai Lu
2008-04-28 8:38 ` Mika Fischer
2008-04-28 9:09 ` Yinghai Lu
2008-04-28 9:44 ` Mika Fischer
2008-04-28 9:58 ` Gabriel C
2008-01-21 6:57 ` [PATCH] x86_64: update e820 instead of updating end_pfn v3 Yinghai Lu
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