From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=56421 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1P5GZT-0000es-Aa for qemu-devel@nongnu.org; Mon, 11 Oct 2010 07:29:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1P5GMT-00051z-B6 for qemu-devel@nongnu.org; Mon, 11 Oct 2010 07:16:10 -0400 Received: from demumfd002.nsn-inter.net ([93.183.12.31]:11540) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1P5GMT-00051i-35 for qemu-devel@nongnu.org; Mon, 11 Oct 2010 07:16:09 -0400 Message-ID: <4CB2F1F0.9010404@nsn.com> Date: Mon, 11 Oct 2010 13:16:00 +0200 From: Bernhard Kohl MIME-Version: 1.0 Subject: Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios References: <20101011101855.GA25030@redhat.com> In-Reply-To: <20101011101855.GA25030@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: ext Gleb Natapov Cc: seabios@seabios.org, qemu-devel@nongnu.org Am 11.10.2010 12:18, schrieb ext Gleb Natapov: > 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? I think this also applies to network booting via gPXE. Usually our VMs have 4 NICs, mixed virtio-net and PCI pass-through. 2 of the NICs shall be used for booting, even if there are hard disks or floppy disks connected. This scenario is currently almost impossible to configure. I already posted a patch 'new parameter boot=on|off for "-net nic" and "-device" NIC devices' which should solve that problem for us. The patch is still under discussion. Of course passing detailed boot device information to SeaBIOS would be the best solution. > Any ideas about qemu > command line syntax? May be somebody whats to implement it? :) > > -- > Gleb. > >