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Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging
From: |
Alexander Graf |
Subject: |
Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging |
Date: |
Tue, 24 Aug 2010 12:45:19 +0200 |
User-agent: |
Thunderbird 2.0.0.23 (X11/20090817) |
Daniel P. Berrange wrote:
> On Tue, Aug 24, 2010 at 12:02:30AM +0200, Alexander Graf wrote:
>
>> The monitor command for hotplugging is in i386 specific code. This is just
>> plain wrong, as S390 just learned how to do hotplugging too and needs to
>> get drives for that.
>>
>> So let's add a generic copy to generic code that handles drive_add in a
>> way that doesn't have pci dependencies.
>>
>> I'm not fully happy with the patch as is. IMHO there should only be a
>> single target agnostic drive_hot_add function available. How we could
>> potentially fit IF_SCSI in there I don't know though.
>>
>
> I'm not sure that this patch is actually neccessary. Via a undocumented,
> sick, dirty hack, you can already use the current drive_add command
> without a PCI address, for both virtio + scsi. In fact not using the
> PCI address with drive_add is the preferred approach in the new qdev
> world even on x86
>
It is certainly necessary since the current code is in a big fat #if
defined(TARGET_I386) block :).
> The key is that you should use if=none for all cases. Here are two
> examples of how libvirt does it currently:
>
> VirtIO:
>
> drive_add dummy
> file=/var/lib/libvirt/images/data.img,if=none,id=drive-virtio-disk1,format=raw
> device_add
> virtio-blk-pci,bus=pci.0,addr=0x0,drive=drive-virtio-disk1,id=virtio-disk1'
>
> SCSI:
>
> drive_add dummy
> file=/var/lib/libvirt/images/data.img,if=none,id=drive-scsi0-0-1,format=raw'
> device_add
> scsi-disk,bus=scsi0.0,scsi-id=1,drive=drive-scsi0-0-1,id=scsi0-0-1
>
> The 'dummy' value there can be absolutely anything you want.
> It is totaly ignored when QEMU sees if=none in 2nd arg.
>
I'd be all for removing the pci-hotplug.c version of drive_add then. But
I think the IF_SCSI option there is to append a drive to an existing
SCSI bus, no?
Alex
- [Qemu-devel] [PATCH 2/5] [S390] Increase amount of virtio pages, (continued)
Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Daniel P. Berrange, 2010/08/24
- Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging,
Alexander Graf <=
- Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Daniel P. Berrange, 2010/08/24
- Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Alexander Graf, 2010/08/24
- Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Daniel P. Berrange, 2010/08/24
- Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Alexander Graf, 2010/08/24
- Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Daniel P. Berrange, 2010/08/24
- Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Markus Armbruster, 2010/08/27
Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Anthony Liguori, 2010/08/24
Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Alexander Graf, 2010/08/24
Re: [Qemu-devel] [PATCH 4/5] Add generic drive hotplugging, Markus Armbruster, 2010/08/27