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Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios |
Date: |
Mon, 11 Oct 2010 13:01:51 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7 |
Am 11.10.2010 12:43, schrieb Gleb Natapov:
> 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?
Right, somehow I assumed that SeaBIOS already has some information about
disks, but now I see that this is exactly the problem you're talking
about. My suggestion wasn't really helpful then.
I think what you described is more or less the only way to do it then.
Kevin
- [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Kevin Wolf, 2010/10/11
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios,
Kevin Wolf <=
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gerd Hoffmann, 2010/10/11
- Re: [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Anthony Liguori, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Anthony Liguori, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Anthony Liguori, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Gleb Natapov, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, H. Peter Anvin, 2010/10/11
- Re: [SeaBIOS] [Qemu-devel] [RFC] Passing boot order from qemu to seabios, Sebastian Herbszt, 2010/10/11