From: "H. Peter Anvin" <hpa@zytor.com>
To: Andi Kleen <ak@muc.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
venkatesh.pallipadi@intel.com, rdreier@cisco.com,
torvalds@linux-foundation.org, gregkh@suse.de, airlied@skynet.ie,
davej@redhat.com, mingo@elte.hu, tglx@linutronix.de,
akpm@linux-foundation.org, arjan@infradead.org,
jesse.barnes@intel.com, linux-kernel@vger.kernel.org,
Suresh Siddha <suresh.b.siddha@intel.com>
Subject: Re: [RFC PATCH 02/12] PAT 64b: Basic PAT implementation
Date: Fri, 14 Dec 2007 11:45:38 -0800 [thread overview]
Message-ID: <4762DD62.6060803@zytor.com> (raw)
In-Reply-To: <20071214102535.GB9705@muc.de>
Andi Kleen wrote:
>> I do know we need to use the low 4 pat mappings to avoid most of the PAT
>> errata issues.
>
> They don't really matter. These are all very old systems who have run
> fine for many years without PAT. It is no problem to let them
> continue to do so and just disable PAT for them. So just clear pat bit in
> CPU initialization for any CPUs with non trivial erratas in this
> area.
>
> PAT is only really needed on modern boxes.
How many mapping types do we actually need? The only ones which are
likely to be used in practice are WB, UC, WC, which still leaves a
spare. (Any intended users of WP or WT?)
-hpa
next prev parent reply other threads:[~2007-12-14 19:58 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-12-13 23:55 [RFC PATCH 00/12] PAT 64b: PAT support for X86_64 venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 01/12] PAT 64b: Add cpu_shutdown() support venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 02/12] PAT 64b: Basic PAT implementation venkatesh.pallipadi
2007-12-14 0:42 ` Andi Kleen
2007-12-14 18:31 ` Venki Pallipadi
2007-12-18 4:50 ` Eric W. Biederman
2007-12-14 3:48 ` Eric W. Biederman
2007-12-14 4:23 ` Eric W. Biederman
2007-12-14 21:10 ` Siddha, Suresh B
2007-12-14 23:34 ` Siddha, Suresh B
2007-12-15 7:55 ` Ingo Molnar
2007-12-14 10:25 ` Andi Kleen
2007-12-14 19:45 ` H. Peter Anvin [this message]
2007-12-18 4:42 ` Eric W. Biederman
2007-12-14 21:06 ` Siddha, Suresh B
2007-12-13 23:55 ` [RFC PATCH 03/12] PAT 64b: drm driver changes for PAT venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 04/12] PAT 64b: reserve_mattr and free_mattr " venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 05/12] PAT 64b: pci mmap conlfict patch venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 06/12] PAT 64b: Add ioremap_wc support venkatesh.pallipadi
2007-12-14 4:17 ` Roland Dreier
2007-12-14 4:28 ` Eric W. Biederman
2007-12-14 4:32 ` Roland Dreier
2007-12-14 4:48 ` Eric W. Biederman
2007-12-14 21:40 ` Siddha, Suresh B
2007-12-14 23:19 ` Andi Kleen
2007-12-18 8:29 ` Eric W. Biederman
2007-12-13 23:55 ` [RFC PATCH 07/12] PAT 64b: dev mem chanegs for pat venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 08/12] PAT 64b: coherent mmap and sysfs bin ioctl venkatesh.pallipadi
2007-12-14 0:19 ` Greg KH
2007-12-14 0:35 ` David Miller
2007-12-14 6:34 ` Greg KH
2007-12-16 21:57 ` Paul Mackerras
2007-12-17 12:41 ` Andi Kleen
2007-12-18 4:30 ` Eric W. Biederman
2007-12-18 4:51 ` H. Peter Anvin
2007-12-18 9:35 ` Andi Kleen
2007-12-18 13:48 ` Eric W. Biederman
2007-12-14 0:43 ` Andi Kleen
2007-12-14 0:54 ` Jesse Barnes
2007-12-14 3:59 ` Eric W. Biederman
2007-12-14 6:02 ` Greg KH
2007-12-14 6:04 ` Eric W. Biederman
2007-12-14 10:19 ` Andi Kleen
2007-12-13 23:55 ` [RFC PATCH 09/12] PAT 64b: map only usable memory in identity mapping venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 10/12] PAT 64b: Make acpi use early map instead of assuming identity map venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 11/12] PAT 64b: devmem do not read pages not mapped in " venkatesh.pallipadi
2007-12-13 23:55 ` [RFC PATCH 12/12] PAT 64b: skip attr tracking for RAM venkatesh.pallipadi
2007-12-14 0:28 ` [RFC PATCH 00/12] PAT 64b: PAT support for X86_64 Dave Airlie
2007-12-14 22:00 ` Siddha, Suresh B
2007-12-14 22:27 ` Dave Airlie
2007-12-14 22:32 ` H. Peter Anvin
2007-12-14 22:37 ` Dave Airlie
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