[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 2/4] block: add block topology options
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] [PATCH 2/4] block: add block topology options |
Date: |
Fri, 5 Feb 2010 16:16:20 +0000 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Christoph Hellwig wrote:
> On Wed, Feb 03, 2010 at 01:00:47PM -0600, Anthony Liguori wrote:
> > But I don't think this is the wrong place to do it. The
> > BlockDriverState reflects that backing device, not the emulated device
> > itself. In this case, you're trying to set a property of the emulated
> > device.
>
> I think that's very borderline. While the emulated device exposes these
> properties, they are in fact a property of the backing storage, the
> right sector and min/max I/O sizes are determined by the backing storage
> device.
>
> > I think these need to be qdev properties of the respective devices.
> > From a UI perspective, you can still expose -drive options for the end
> > user to consume, but this data should be associated with the devices
> > themselves.
>
> In addition to not really beeing more logical this would be a lot more
> effort. We'd need to add properties to all the device, which means
> including dealing with the n+1 ide variants, the virtio-pci proxy, etc.
>
> If you believe it really needs to be in the qdev properties I'll
> implement it, but I suspect the current version is a better idea.
If you move your VM to a new system with different backing devices,
sometimes you want to be sure there is no guest-visible change. Or
even if you just replace a drive - you might prefer confidence that
the guest sees no change.
Even if you just convert between qcow2 and a raw block device, or the
other way, you'll sometimes want to be sure it's not guest-visible.
-- Jamie