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Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in revers
From: |
Daniel P. Berrange |
Subject: |
Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order |
Date: |
Mon, 5 Dec 2016 17:34:48 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
On Mon, Dec 05, 2016 at 04:21:22PM +0100, Greg Kurz wrote:
> The current code recursively applies global properties from child up to
> parent. So, if you have:
>
> -global virtio-pci.disable-modern=on
> -global virtio-blk-pci.disable-modern=off
>
> Then the default value of disable-modern for a virtio-blk-pci device is on,
> which looks wrong from an OOP perspective.
>
> This patch reverses the logic, so that a child property always prevail.
>
> This fixes a subtle bug that got introduced in 2.7 with commit "9a4c0e220d8a
> hw/virtio-pci: fix virtio behaviour" for older (< 2.7) machine types: the
> HW_COMPAT_2_6 macro contains global virtio-pci.disable-* properties which
> would silently override global properties passed on the command line for
> virtio subtypes.
>
> Signed-off-by: Greg Kurz <address@hidden>
> ---
>
> AFAIK, libvirt's XML doesn't know about modern/legacy modes for virtio
> devices. Early adopters of virtio 1.0 had to rely on the <qemu:commandline>
> tag to pass global properties to QEMU. This patch ensures that XML files
> used with older machine types remain valid with newer versions of QEMU.
FYI, we explicitly do *not* guarantee any kind of stability/compatibility
if you use qemu:commandline. Users should expect it to break when they
upgrade QEMU and/or libvirt.
Regards,
Daniel
--
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- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, (continued)
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Eduardo Habkost, 2016/12/05
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Cornelia Huck, 2016/12/05
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Eduardo Habkost, 2016/12/05
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Halil Pasic, 2016/12/05
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Greg Kurz, 2016/12/06
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Halil Pasic, 2016/12/06
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Greg Kurz, 2016/12/06
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Halil Pasic, 2016/12/06
- Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Greg Kurz, 2016/12/05
Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Greg Kurz, 2016/12/05
Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order,
Daniel P. Berrange <=
Re: [Qemu-devel] [PATCH for-2.8] qdev: apply global properties in reverse order, Stefan Hajnoczi, 2016/12/06