From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=60614 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1P5Hwq-0007vd-9p for qemu-devel@nongnu.org; Mon, 11 Oct 2010 08:57:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1P5HnX-0006ah-Ms for qemu-devel@nongnu.org; Mon, 11 Oct 2010 08:48:12 -0400 Received: from mail-vw0-f45.google.com ([209.85.212.45]:33634) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1P5HnX-0006aS-Hb for qemu-devel@nongnu.org; Mon, 11 Oct 2010 08:48:11 -0400 Received: by vws11 with SMTP id 11so378823vws.4 for ; Mon, 11 Oct 2010 05:48:10 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4CB2F1F0.9010404@nsn.com> References: <20101011101855.GA25030@redhat.com> <4CB2F1F0.9010404@nsn.com> Date: Mon, 11 Oct 2010 13:48:09 +0100 Message-ID: Subject: Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios From: Stefan Hajnoczi Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Bernhard Kohl Cc: seabios@seabios.org, qemu-devel@nongnu.org, ext Gleb Natapov On Mon, Oct 11, 2010 at 12:16 PM, Bernhard Kohl wro= te: > Am 11.10.2010 12:18, schrieb ext Gleb Natapov: >> >> Currently if VM is started with multiple disks it is almost impossible t= o >> 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=3Don 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. =A0PCI bus address is not enough since not al= l >> 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: >> =A0 =A0 bus type (isa/pci), >> =A0 =A0 address on a bus (16 bit base address for isa, b/s/f for pci) >> =A0 =A0 device type (ATA/SCSI/VIRTIO) >> =A0 =A0 device path (slave/master for ATA, LUN for SCSI, nothing for vir= tio) >> >> 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. Here is a gPXE to support fw_cfg. You can pass gPXE script files from the host to gPXE inside the guest. This means you can boot specific NICs: http://patchwork.ozlabs.org/patch/43777/ Just wanted to post the link because it is related to the gPXE side of this discussion. Stefan