From: "H. Peter Anvin" <hpa@zytor.com>
To: Dave Airlie <airlied@gmail.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>,
Dave Airlie <airlied@skynet.ie>,
venkatesh.pallipadi@intel.com, ak@muc.de, ebiederm@xmission.com,
rdreier@cisco.com, torvalds@linux-foundation.org, gregkh@suse.de,
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
Subject: Re: [RFC PATCH 00/12] PAT 64b: PAT support for X86_64
Date: Fri, 14 Dec 2007 14:32:02 -0800 [thread overview]
Message-ID: <47630462.6040203@zytor.com> (raw)
In-Reply-To: <21d7e9970712141427h25c84e9g76237a93e634fa76@mail.gmail.com>
Dave Airlie wrote:
> On Dec 15, 2007 8:00 AM, Siddha, Suresh B <suresh.b.siddha@intel.com> wrote:
>> On Fri, Dec 14, 2007 at 12:28:25AM +0000, Dave Airlie wrote:
>>> Yes, the main use for GPUs is to have RAM pages mapped WC, and placed into
>>> a GART on the GPU side, currently for Intel IGD we are okay as the CPU can
>>> access the GPU GART aperture, but other chips exist where this isn't
>>> possible, I think poulsbo and possible some of the AMD IGPs..
>> Ok. So how is it working today on these platforms with no PAT support.
>> Open source drivers use UC or WB on these platforms? As this RAM is not
>> contiguous, one can't use MTRRs to set WC. Right?
>>
>> Well, if WC is needed for RAM, then we have to address it too.
>>
>
> It doesn't work really, which is mostly the problem :)
>
> We mostly use UC on these pages, or WB within cache coherent domains.
> mtrrs are totally useless in this situation.
>
In what sense does it not work?
-hpa
next prev parent reply other threads:[~2007-12-14 22:40 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
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 [this message]
2007-12-14 22:37 ` Dave Airlie
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