From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1751956AbcGRJDM (ORCPT <rfc822;w@1wt.eu>);
	Mon, 18 Jul 2016 05:03:12 -0400
Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:32536 "EHLO
	mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1751886AbcGRJDK (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 18 Jul 2016 05:03:10 -0400
X-IBM-Helo: d06dlp03.portsmouth.uk.ibm.com
X-IBM-MailFrom: cornelia.huck@de.ibm.com
X-IBM-RcptTo: kvm@vger.kernel.org;linux-kernel@vger.kernel.org
Date: Mon, 18 Jul 2016 11:02:27 +0200
From: Cornelia Huck <cornelia.huck@de.ibm.com>
To: Namhyung Kim <namhyung@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Paolo Bonzini <pbonzini@redhat.com>,
        Radim Kr??m???? <rkrcmar@redhat.com>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Anthony Liguori <aliguori@amazon.com>,
        Anton Vorontsov <anton@enomsg.org>, Colin Cross <ccross@android.com>,
        Kees Cook <keescook@chromium.org>, Tony Luck <tony.luck@intel.com>,
        Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@kernel.org>,
        Minchan Kim <minchan@kernel.org>, kvm@vger.kernel.org,
        qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org
Subject: Re: [PATCH 1/3] virtio: Basic implementation of virtio pstore
 driver
In-Reply-To: <20160718082955.GA12086@danjae.aot.lge.com>
References: <1468816661-6345-1-git-send-email-namhyung@kernel.org>
	<1468816661-6345-2-git-send-email-namhyung@kernel.org>
	<20160718095439.1eabb340.cornelia.huck@de.ibm.com>
	<20160718082955.GA12086@danjae.aot.lge.com>
Organization: IBM Deutschland Research & Development GmbH Vorsitzende des
 Aufsichtsrats: Martina Koederitz =?UTF-8?B?R2VzY2jDpGZ0c2bDvGhydW5nOg==?=
 Dirk Wittkopp Sitz der Gesellschaft: =?UTF-8?B?QsO2Ymxpbmdlbg==?=
 Registergericht: Amtsgericht Stuttgart, HRB 243294
X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
X-TM-AS-MML: disable
X-Content-Scanned: Fidelis XPS MAILER
x-cbid: 16071809-0032-0000-0000-000001EA8815
X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused
x-cbparentid: 16071809-0033-0000-0000-00001BE39E9F
Message-Id: <20160718110227.6ff6d1a2.cornelia.huck@de.ibm.com>
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-18_05:,,
 signatures=0
X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0
 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam
 adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000
 definitions=main-1607180106
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, 18 Jul 2016 17:29:55 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> On Mon, Jul 18, 2016 at 09:54:39AM +0200, Cornelia Huck wrote:
> > On Mon, 18 Jul 2016 13:37:39 +0900
> > Namhyung Kim <namhyung@kernel.org> wrote:

> > > +#define VIRT_PSTORE_ORDER    2
> > > +#define VIRT_PSTORE_BUFSIZE  (4096 << VIRT_PSTORE_ORDER)
> > 
> > It may make sense to make the size of the buffer configurable through
> > the config space.
> 
> Right.  I'm considering it too, but it needs a buffer larger than
> kmsg_bytes (= 10K) to work properly in the current implementation.  As
> this version is just to verify the idea is sane and useful, I used a
> fixed size buffer.  Will change in the next version.

Sure, that makes sense for a prototype. We can guard any config space
entry with a feature bit, but this one makes sense to add from the
beginning.

> > Speaking of the standard: I think it makes sense to at least reserve a
> > device id for pstore, as the idea is sound. Maybe prepare a patch to
> > the standard as well if you have time?
> 
> I'd love to.  As I mentioned earlier, I don't have enough knowledge in
> this area.  Could you please provide some links about how can I do that?

See the virtio page at OASIS
(https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio)
for a link to our subversion (yes...) repository. Just do two patches:
one to reserve a device id, and one that specifies how device and
driver work. (For examples, look at the proposed device types that have
been posted to the virtualization lists, e.g. virtio-crypto or
virtio-sdm). You just need to be patient, we're currently a bit
stalled...