From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1LBEGL-0007Uh-M3
	for qemu-devel@nongnu.org; Fri, 12 Dec 2008 15:05:25 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1LBEGH-0007Se-SS
	for qemu-devel@nongnu.org; Fri, 12 Dec 2008 15:05:25 -0500
Received: from [199.232.76.173] (port=35530 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1LBEGH-0007SY-Na
	for qemu-devel@nongnu.org; Fri, 12 Dec 2008 15:05:21 -0500
Received: from rn-out-0910.google.com ([64.233.170.191]:49545)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <blauwirbel@gmail.com>) id 1LBEGH-0006db-7w
	for qemu-devel@nongnu.org; Fri, 12 Dec 2008 15:05:21 -0500
Received: by rn-out-0910.google.com with SMTP id 56so1490538rnw.8
	for <qemu-devel@nongnu.org>; Fri, 12 Dec 2008 12:05:20 -0800 (PST)
Message-ID: <f43fc5580812121205p7d6cc2fjb8c918e4f3b44019@mail.gmail.com>
Date: Fri, 12 Dec 2008 22:05:19 +0200
From: "Blue Swirl" <blauwirbel@gmail.com>
Subject: Re: [Qemu-devel] [PATCH 2 of 5] add can_dma/post_dma for direct IO
In-Reply-To: <4942B913.8010306@codemonkey.ws>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <patchbomb.1229105802@duo.random>
	<cc5d812eb9369a7ad2ef.1229105804@duo.random>
	<f43fc5580812121100s194bc5c8n69c86ded12db8c55@mail.gmail.com>
	<4942B913.8010306@codemonkey.ws>
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org
Cc: chrisw@redhat.com, Gerd Hoffmann <kraxel@redhat.com>, kvm@vger.kernel.org, avi@redhat.com

On 12/12/08, Anthony Liguori <anthony@codemonkey.ws> wrote:
> Blue Swirl wrote:
>
> > On 12/12/08, Andrea Arcangeli <aarcange@redhat.com> wrote:
> >
> >
> > > From: Andrea Arcangeli <aarcange@redhat.com>
> > >
> > >  Add can_dma and post_dma methods needed before/after direct IO to guest
> > >  physical memory.
> > >
> > >  Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
> > >
> > >
> >
> >
> >
> > >  +        /* nonlinear range */
> > >  +        if (pd_first != pd)
> > >  +            return NULL;
> > >
> > >
> >
> > In my tests on Sparc32, IOMMU can map a linear DVMA range to several
> > non-linear physical pages, so this case should be handled correctly.
> >
> >
>
>  I think we should go back to Fabrice's earliest suggestion here.  We should
> just have a simple map/unmap lock/unlock API for physical memory.  That
> should be the base API IMHO.

Beautiful!

>  As long the map function goes from guest physical => host virtual, it can
> work for everything we care about.
>
>  This is orthogonal to an API dealing with scatter/gather lists and
> translation to and from them.

So again we tried to solve too many problems at once.