From: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
To: Christoph Hellwig <hch@infradead.org>
Cc: Keir Fraser <Keir.Fraser@cl.cam.ac.uk>,
linux-kernel@vger.kernel.org, akpm@osdl.org, riel@redhat.com,
kurt@garloff.de, Ian.Pratt@cl.cam.ac.uk,
Christian.Limpach@cl.cam.ac.uk
Subject: Re: [PATCH] Xen/i386 cleanups - AGP bus/phys cleanups
Date: Wed, 16 Mar 2005 14:58:37 +0000 [thread overview]
Message-ID: <E1DBZyo-0003Ut-00@mta1.cl.cam.ac.uk> (raw)
In-Reply-To: Your message of "Wed, 16 Mar 2005 14:31:30 GMT." <20050316143130.GA21959@infradead.org>
> On Wed, Mar 16, 2005 at 11:48:29AM +0000, Keir Fraser wrote:
> > This patch cleans up AGP driver treatment of bus/device memory. Every
> > use of virt_to_phys/phys_to_virt should properly be converting between
> > virtual and bus addresses: this distinction really matters for the Xen
> > hypervisor.
>
> It's bogus either way. You must never use virt_to_phys or virt_to_bus
> for bus address. For systems with an IOMMU there's no 1:1 mapping.
Well, I'd say it's less bogus: it makes the intention clearer, and it
is a 'good enough' improvement for Xen. Indeed, it's good enough for
all the architectures that actually use the AGP drivers (all have no
IOMMU, or an IOMMU only to support legacy 32-bit I/O interfaces).
-- Keir
next prev parent reply other threads:[~2005-03-16 15:00 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-16 11:48 Keir Fraser
2005-03-16 14:31 ` Christoph Hellwig
2005-03-16 14:58 ` Keir Fraser [this message]
2005-03-16 15:01 ` Rik van Riel
2005-03-16 18:10 ` Christoph Hellwig
2005-03-16 18:35 ` Keir Fraser
2005-03-16 18:42 ` Jesse Barnes
2005-03-16 19:08 ` Keir Fraser
2005-03-16 19:06 ` Christoph Hellwig
2005-03-16 19:11 ` Keir Fraser
2005-03-16 17:40 ` Alan Cox
2005-03-16 17:54 ` Jesse Barnes
2005-03-16 21:24 ` Paul Mackerras
2005-03-16 22:06 ` Jesse Barnes
2005-03-16 23:55 ` Rik van Riel
2005-03-17 0:39 ` Paul Mackerras
2005-03-17 1:05 ` Tupshin Harper
2005-03-17 3:44 ` Rik van Riel
2005-03-17 4:42 ` Christoph Hellwig
2005-03-17 4:58 ` Rik van Riel
2005-03-17 9:16 ` Keir Fraser
2005-03-17 9:34 ` Paul Mackerras
2005-03-17 10:56 ` Keir Fraser
2005-03-19 10:07 ` Eric W. Biederman
2005-03-19 10:56 ` Christian Limpach
2005-03-19 13:01 ` Keir Fraser
2005-03-17 13:53 ` Alan Cox
2005-03-18 0:16 ` Paul Mackerras
2005-03-18 4:23 ` Rik van Riel
2005-03-18 9:05 ` Keir Fraser
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=E1DBZyo-0003Ut-00@mta1.cl.cam.ac.uk \
--to=keir.fraser@cl.cam.ac.uk \
--cc=Christian.Limpach@cl.cam.ac.uk \
--cc=Ian.Pratt@cl.cam.ac.uk \
--cc=akpm@osdl.org \
--cc=hch@infradead.org \
--cc=kurt@garloff.de \
--cc=linux-kernel@vger.kernel.org \
--cc=riel@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®