From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NDDOU-0003Tx-G4 for qemu-devel@nongnu.org; Wed, 25 Nov 2009 03:38:34 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NDDOR-0003Rs-1e for qemu-devel@nongnu.org; Wed, 25 Nov 2009 03:38:34 -0500 Received: from [199.232.76.173] (port=39257 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NDDOQ-0003Rn-Kt for qemu-devel@nongnu.org; Wed, 25 Nov 2009 03:38:30 -0500 Received: from cantor2.suse.de ([195.135.220.15]:50610 helo=mx2.suse.de) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NDDOQ-0000pD-4G for qemu-devel@nongnu.org; Wed, 25 Nov 2009 03:38:30 -0500 Subject: Re: [Qemu-devel] [PATCH 12/13] Add zipl bootloader interpreter Mime-Version: 1.0 (Apple Message framework v1077) Content-Type: text/plain; charset=us-ascii From: Alexander Graf In-Reply-To: <20091125083537.GA25731@ochil.suse.de> Date: Wed, 25 Nov 2009 09:38:27 +0100 Content-Transfer-Encoding: quoted-printable Message-Id: <2360D08A-1819-404F-B976-B2870D15054E@suse.de> References: <1259083781-14642-1-git-send-email-agraf@suse.de> <4B0C3375.4010206@codemonkey.ws> <200911242039.55345.maw48@cantab.net> <4B0C4BC0.7070006@codemonkey.ws> <20091125083537.GA25731@ochil.suse.de> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Hannes Reinecke Cc: Carsten Otte , Aurelien Jarno , qemu-devel@nongnu.org, Mark Williamson On 25.11.2009, at 09:35, Hannes Reinecke wrote: > On Tue, Nov 24, 2009 at 03:10:24PM -0600, Anthony Liguori wrote: >> Hi Mark! >>=20 >> Mark Williamson wrote: >>> Way back in the mists of time (uh, something like that 2004-05) I = had some=20 >>> discussions with some of the S390 people about using kboot for more=20= >>> flexible boot, since it tallied with their interests. Although at = that=20 >>> point I had the impression that zipl was restricted to only one boot=20= >>> option anyhow, so if it can now choose from a list then maybe they = just=20 >>> enhanced what they had. >>>=20 >>> Anthony, you might remember these discussions? I don't know if they = went=20 >>> anywhere with it. >>>=20 >>=20 >> I do, that's why I brought it up. AFAICT, there hasn't been a lot of=20= >> progress with kboot. Carsten or Alex would probably know better if = anyone=20 >> is actually using it on s390s. >>=20 > No, not to my knowledge. >=20 > There have been some discussion as if kboot would be beneficial here, = but > especially for s390 it doesn't make a lot of sense. Thanks for clarifying this! > kboot is okay for scenarios where you have a _lot_ of modules in the = default > kernel, but need only a very small subset to get the system = bootstrapped. > Then you can built a kboot kernel with the driver subset for = bootstrapping > and have that loading the 'normal' kernel which then loads all = remaining > modules. >=20 > If you have (like s390) only about 8 driver modules to care about it's > pretty much pointless as the kboot kernel will have the same = configuration > than the normal kernel. So you'll end up with loading the same kernel = twice. >=20 > And won't change the situation here, as you still have to do the = initial > bootstrap somehow. And as this should be quite close to the original = system > you'll end up having to support zipl anyway. Yes, you'd basically end up writing a zipl interpreter inside the initrd = of kboot. Bleks. > So back to the zipl question, it might be an idea to support initially > the SCSI disk layout only. This has the advantage of being far simpler > as the DASD disk layout and should be pretty straightforward to = handle. That's exactly what my zipl patch does. DASD has 4k sector sizes, so = DASD layouts are not supported. Fortunately virtio in qemu only exports = 512 bytes sector sizes for now, so when you install the VM onto virtio, = you're good. Alex=