From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1LOxDU-0004Nv-GD
	for qemu-devel@nongnu.org; Mon, 19 Jan 2009 11:43:12 -0500
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1LOxDS-0004N0-Tj
	for qemu-devel@nongnu.org; Mon, 19 Jan 2009 11:43:12 -0500
Received: from [199.232.76.173] (port=39299 helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1LOxDS-0004Ms-Os
	for qemu-devel@nongnu.org; Mon, 19 Jan 2009 11:43:10 -0500
Received: from mx2.redhat.com ([66.187.237.31]:40252)
	by monty-python.gnu.org with esmtp (Exim 4.60)
	(envelope-from <avi@redhat.com>) id 1LOxDS-0005NA-6R
	for qemu-devel@nongnu.org; Mon, 19 Jan 2009 11:43:10 -0500
Message-ID: <4974ACD0.601@redhat.com>
Date: Mon, 19 Jan 2009 18:39:44 +0200
From: Avi Kivity <avi@redhat.com>
MIME-Version: 1.0
Subject: Re: [Qemu-devel] [PATCH 1/5] Add target memory mapping API
References: <1232308399-21679-1-git-send-email-avi@redhat.com>
	<4974943B.4020507@redhat.com> <49749EC5.3080704@codemonkey.ws>
	<200901191618.10082.paul@codesourcery.com>
	<4974AB48.1070301@codemonkey.ws>
In-Reply-To: <4974AB48.1070301@codemonkey.ws>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
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: Anthony Liguori <anthony@codemonkey.ws>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>, Paul Brook <paul@codesourcery.com>, qemu-devel@nongnu.org

Anthony Liguori wrote:
> Paul Brook wrote:
>> It looks like what you're actually doing is pushing the bounce buffer 
>> allocation into the individual packet consumers.
>>
>> Maybe a solution to this is a 'do IO on IOVEC' actor, with an 
>> additional flag that says whether it is acceptable to split the 
>> allocation. That way both block and packet interfaces use the same 
>> API, and avoids proliferation of manual bounce buffers in packet 
>> devices.
>>   
>
> I think there may be utility in having packet devices provide the 
> bounce buffers, in which case, you could probably unique both into a 
> single function with a flag.  But why not just have two separate 
> functions?
>
> Those two functions can live in exec.c too.  The nice thing about 
> using map() is that it's easily overriden and chained.  So what I'm 
> proposing.
>
> cpu_physical_memory_map()
> cpu_physical_memory_unmap()

This should be the baseline API with the rest using it.

> do_streaming_IO(map, unmap, ioworker, opaque);

Why pass map and unmap?

grant based devices needn't go through this at all, since you never mix 
grants and physical addresses, and since grants never need bouncing.

> do_packet_IO(map, unmap, buffer, size, ioworker, opaque);

If you pass the buffer then the device needs to allocate large amounts 
of bounce memory.


-- 
error compiling committee.c: too many arguments to function