From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=36134 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1P5KXp-0005oW-Vp for qemu-devel@nongnu.org; Mon, 11 Oct 2010 11:44:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1P5KWK-0005dk-Ce for qemu-devel@nongnu.org; Mon, 11 Oct 2010 11:42:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39001) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1P5KWK-0005de-5n for qemu-devel@nongnu.org; Mon, 11 Oct 2010 11:42:36 -0400 Message-ID: <4CB33066.5010903@redhat.com> Date: Mon, 11 Oct 2010 17:42:30 +0200 From: Avi Kivity MIME-Version: 1.0 References: <20101011101855.GA25030@redhat.com> <4CB328A2.9090608@redhat.com> <20101011153928.GE28008@redhat.com> In-Reply-To: <20101011153928.GE28008@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [SeaBIOS] [RFC] Passing boot order from qemu to seabios List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: seabios@seabios.org, qemu-devel@nongnu.org On 10/11/2010 05:39 PM, Gleb Natapov wrote: > On Mon, Oct 11, 2010 at 05:09:22PM +0200, Avi Kivity wrote: > > On 10/11/2010 12:18 PM, Gleb Natapov wrote: > > >Currently if VM is started with multiple disks it is almost impossible to > > >guess which one of them will be used as boot device especially if there > > >is a mix of ATA/virtio/SCSI devices. Essentially BIOS decides the order > > >and without looking into the code you can't tell what the order will > > >be (and in qemu-kvm if boot=on is used it brings even more havoc). We > > >should allow fine-grained control of boot order from qemu command line, > > >or as a minimum control what device will be used for booting. > > > > > >To do that along with inventing syntax to specify boot order on qemu > > >command line we need to communicate boot order to seabios via fw_cfg > > >interface. For that we need to have a way to unambiguously specify a > > >disk from qemu to seabios. PCI bus address is not enough since not all > > >devices are PCI (do we care about them?) and since one PCI device may > > >control more then one disk (ATA slave/master, SCSI LUNs). We can do what > > >EDD specification does. Describe disk as: > > > bus type (isa/pci), > > > address on a bus (16 bit base address for isa, b/s/f for pci) > > > device type (ATA/SCSI/VIRTIO) > > > device path (slave/master for ATA, LUN for SCSI, nothing for virtio) > > > > > >Will it cover all use cased? Any other ideas? Any ideas about qemu > > >command line syntax? May be somebody whats to implement it? :) > > > > Instead of fwcfg, we should store the boot order in the bios. This > > allows seabios to implement persistent boot selection and control > > boot order from within the guest. > > > It is not "instead of" it is in a best case "in addition too". First of > all seabios does not have persistent storage currently and second I much > prefer specifying boot device from command line instead of navigating > bios menus. That what we have to do on real HW because there is not > other way to do it, but in virtualization we can do better. Ok. So fwcfg will have an option "do your default thing" which the bios can take as a hint to look in cmos memory. -- error compiling committee.c: too many arguments to function