From: Roman Zippel <zippel@fh-brandenburg.de>
To: Mark Mokryn <mark@sangate.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: ioremap_nocache problem?
Date: Tue, 23 Jan 2001 19:12:36 +0100 (MET) [thread overview]
Message-ID: <Pine.GSO.4.10.10101231903380.14027-100000@zeus.fh-brandenburg.de> (raw)
In-Reply-To: <3A6D5D28.C132D416@sangate.com>
Hi,
On Tue, 23 Jan 2001, Mark Mokryn wrote:
> ioremap_nocache does the following:
> return __ioremap(offset, size, _PAGE_PCD);
>
> However, in drivers/char/mem.c (2.4.0), we see the following:
>
> /* On PPro and successors, PCD alone doesn't always mean
> uncached because of interactions with the MTRRs. PCD | PWT
> means definitely uncached. */
> if (boot_cpu_data.x86 > 3)
> prot |= _PAGE_PCD | _PAGE_PWT;
>
> Does this mean ioremap_nocache() may not do the job?
ioremap creates a new mapping that shouldn't interfere with MTRR, whereas
you can map a MTRR mapped area into userspace. But I'm not sure if it's
correct that no flag is set for boot_cpu_data.x86 <= 3...
bye, Roman
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next prev parent reply other threads:[~2001-01-23 18:12 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-01-23 10:30 Mark Mokryn
2001-01-23 16:53 ` Timur Tabi
2001-01-25 15:16 ` Stephen C. Tweedie
2001-01-25 15:56 ` Timur Tabi
2001-01-25 16:44 ` Roman Zippel
2001-01-25 16:49 ` Timur Tabi
2001-01-26 10:39 ` Stephen C. Tweedie
[not found] ` <20010125165001Z132264-460+11@vger.kernel.org>
2001-01-25 17:04 ` Jeff Hartmann
2001-01-25 17:11 ` Timur Tabi
[not found] ` <E14LpvQ-0008Pw-00@mail.valinux.com>
2001-01-25 17:47 ` Jeff Hartmann
2001-01-25 17:53 ` Timur Tabi
2001-01-26 10:43 ` Stephen C. Tweedie
2001-01-26 16:32 ` Eric W. Biederman
2001-01-26 19:22 ` Timur Tabi
[not found] ` <20010125175308Z130507-460+45@vger.kernel.org>
2001-01-25 18:13 ` Jeff Hartmann
2001-01-25 18:18 ` Timur Tabi
[not found] ` <E14Lqyt-0003z6-00@mail.valinux.com>
2001-01-25 18:46 ` Jeff Hartmann
[not found] ` <200101251556.f0PFuPd01743@mail.redhat.com>
2001-01-26 10:37 ` Stephen C. Tweedie
2001-01-23 18:12 ` Roman Zippel [this message]
2001-01-23 18:38 ` Timur Tabi
2001-01-24 0:50 ` David Wragg, David Wragg
2001-01-24 15:14 ` Timur Tabi
[not found] ` <E14LRce-0008FU-00@diver.doc.ic.ac.uk>
2001-01-24 15:39 ` David Wragg
[not found] ` <20010123183847Z131216-18594+636@vger.kernel.org>
2001-01-24 1:01 ` David Wragg
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