From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:34858) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qorhl-0000SR-OW for qemu-devel@nongnu.org; Thu, 04 Aug 2011 02:46:54 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Qorhk-0004Gi-NJ for qemu-devel@nongnu.org; Thu, 04 Aug 2011 02:46:53 -0400 Received: from cantor2.suse.de ([195.135.220.15]:46632 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qorhk-0004FX-9e for qemu-devel@nongnu.org; Thu, 04 Aug 2011 02:46:52 -0400 Message-ID: <4E3A405A.5050502@suse.de> Date: Thu, 04 Aug 2011 08:46:50 +0200 From: Hannes Reinecke MIME-Version: 1.0 References: <1312376904-16115-1-git-send-email-armbru@redhat.com> <1312376904-16115-17-git-send-email-armbru@redhat.com> <4E3A38D1.8040802@suse.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2 16/45] scsi-disk: Track tray locked state List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: kwolf@redhat.com, quintela@redhat.com, stefano.stabellini@eu.citrix.com, qemu-devel@nongnu.org, lcapitulino@redhat.com, amit.shah@redhat.com, hch@lst.de On 08/04/2011 08:39 AM, Markus Armbruster wrote: > Hannes Reinecke writes: > >> On 08/03/2011 03:07 PM, Markus Armbruster wrote: >>> We already track it in BlockDriverState. Just like tray open/close >>> state, we should track it in the device models instead, because it's >>> device state. >>> >>> Signed-off-by: Markus Armbruster >>> --- >>> hw/scsi-disk.c | 4 +++- >>> 1 files changed, 3 insertions(+), 1 deletions(-) >>> >>> diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c >>> index db72b86..8ca69f2 100644 >>> --- a/hw/scsi-disk.c >>> +++ b/hw/scsi-disk.c >>> @@ -73,6 +73,7 @@ struct SCSIDiskState >>> char *serial; >>> SCSISense sense; >>> bool tray_open; >>> + bool tray_locked; >>> }; >>> >> Hmm. Shouldn't we use a more generic 'flags' here and have bits for >> the individual tray states? >> Feels like a waste to have individual values here. > > On my system, struct SCSIDiskState is 248 bytes before my series (5 > bytes of padding at the end), and 248 bytes after (3 bytes padding). W= e > use one per disk. > > I dare say switching to flags won't make a noticable difference in > memory use ;) > > The bool members are easy to read and hard to screw up. > > Flags can be nicer when you manipulate several of them together. Well, but this just proves my point. Each 'bool' variable takes up one byte, of which only one bit is=20 used. Which qualifies as a waste of space. But if that's okay with everyone and the general consensus on how to=20 code flags in qemu, I'll shut up. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: J. Hawn, J. Guild, F. Imend=F6rffer, HRB 16746 (AG N=FCrnberg)