From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from [140.186.70.92] (port=50113 helo=eggs.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1PiQpO-0000sS-K3
	for qemu-devel@nongnu.org; Thu, 27 Jan 2011 07:19:55 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1PiQpN-0005mH-DV
	for qemu-devel@nongnu.org; Thu, 27 Jan 2011 07:19:54 -0500
Received: from mx1.redhat.com ([209.132.183.28]:35572)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1PiQpN-0005m2-6Z
	for qemu-devel@nongnu.org; Thu, 27 Jan 2011 07:19:53 -0500
Message-ID: <4D416342.6080001@redhat.com>
Date: Thu, 27 Jan 2011 13:21:22 +0100
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
References: <m3oc72eed1.fsf@blackfin.pond.sub.org>
In-Reply-To: <m3oc72eed1.fsf@blackfin.pond.sub.org>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Subject: [Qemu-devel] Re: Commit 622b520f changed -drive if=scsi, index=N,
	intentional?
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.nongnu.org/archive/html/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: Markus Armbruster <armbru@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, qemu-devel@nongnu.org, Hannes Reinecke <hare@suse.de>

Am 27.01.2011 13:10, schrieb Markus Armbruster:
> Consider -drive if=scsi,index=12,...
> 
> Before the commit, index=12 meant bus=1,unit=5.  Example:
> 
>     [...]
> 
>     Two scsi-buses, and scsi1-cd5 with scsi-id 5 is on the second one,
>     i.e. bus=1, unit=5.
> 
> After the commit, it means bus=0,unit=12.  The drive is created, but not
> the guest device.  That's because lsi53c895a supports only 7 units
> (LSI_MAX_DEVS), and scsi_bus_legacy_handle_cmdline() ignores drives with
> unit numbers exceeding that limit.  Example:
> 
>     [...]
> 
>     One scsi-bus, and scsi1-cd5 nowhere to be found.
> 
> I'd call this a regression.
> 
> What now?

That's a really good question. We could do something like this:

--- a/blockdev.c
+++ b/blockdev.c
@@ -192,7 +192,7 @@ DriveInfo *drive_init(QemuOpts *opts, int
default_to_scsi)
             max_devs = MAX_IDE_DEVS;
         } else if (!strcmp(buf, "scsi")) {
            type = IF_SCSI;
-            max_devs = MAX_SCSI_DEVS;
+            max_devs = 7;
         } else if (!strcmp(buf, "floppy")) {
            type = IF_FLOPPY;
             max_devs = 0;

That's very obviously not much more than a hack, but I don't think
blockdev.c can get the real number easily (please prove me wrong). With
this hack, we would get the old behaviour for -drive (which doesn't use
any other controller anyway) and you can still use -device to attach
more devices to a non-lsi bus.

Kevin