From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=37869 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1P5FrI-0001tw-Lp for qemu-devel@nongnu.org; Mon, 11 Oct 2010 06:43:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1P5FrH-0007c6-M1 for qemu-devel@nongnu.org; Mon, 11 Oct 2010 06:43:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:64949) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1P5FrH-0007c1-Ek for qemu-devel@nongnu.org; Mon, 11 Oct 2010 06:43:55 -0400 Date: Mon, 11 Oct 2010 12:43:51 +0200 From: Gleb Natapov Subject: Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios Message-ID: <20101011104351.GB25030@redhat.com> References: <20101011101855.GA25030@redhat.com> <4CB2E7D0.1010702@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4CB2E7D0.1010702@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: seabios@seabios.org, qemu-devel@nongnu.org On Mon, Oct 11, 2010 at 12:32:48PM +0200, Kevin Wolf wrote: > Am 11.10.2010 12:18, schrieb 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?) > > Floppy? Yes, I think we do. > > > 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) > > If we had a qdev ID for all devices (which I think we should have > anyway), would this work or is a string not really handy enough? > Given qdev ID how seabios knows what device it corresponds to? -- Gleb.