Re: [Qemu-devel] [PATCH v6 2/7] hw/misc: add vmcoreinfo device

[Igor Mammedov]

On Mon, 9 Oct 2017 12:03:36 +0100
"Daniel P. Berrange" <address@hidden> wrote:

> On Mon, Sep 11, 2017 at 06:59:24PM +0200, Marc-André Lureau wrote:
> > See docs/specs/vmcoreinfo.txt for details.
> > 
> > "etc/vmcoreinfo" fw_cfg entry is added when using "-device vmcoreinfo".  
> 
> I'm wondering if you considered just adding the entry to fw_cfg by
> default, without requiring any -device arg ? Unless I'm misunderstanding,
> this doesn't feel like a device to me - its just a well known bucket
> in fw_cfg IIUC ?  Obviously its existance would need to be tied to
> the latest machine type for ABI reasons though. The benefit of this
> is that it would "just work" without us having to plumb it through to
> all the downstream applications that use QEMU for mgmt guest (OpenStack,
> oVirt, GNOME Boxes, virt-manager, and countless other mgmt apps).
it follows model set by pvpanic device, it's easier to manage from migration
POV, one could use it even for old machine types with new qemu (just by adding
device, it makes instance not backwards migratable to old qemu but should work
for forward migration) and if user doesn't need it, device could be just omitted
from CLI.

> 
> Regards,
> Daniel