Re: [Qemu-block] [Qemu-devel] storing machine data in qcow images?

[Eduardo Habkost]

On Tue, May 22, 2018 at 09:35:55AM +0200, Gerd Hoffmann wrote:
>   Hi,
> 
> > You must /sometimes/ supply the correct machine type.
> > 
> > It is quite dependent on the guest OS you have installed, and even
> > just how the guest OS is configured.  In general Linux is very
> > flexible and can adapt to a wide range of hardware, automatically
> > detecting things as needed. It is possible for a sysadmin to build
> > a Linux image in a way that would only work with I440FX, but I
> > don't think it would be common to see that.
> 
> I think it would be pretty hard to actually build such an image.
> 
> The more critical thing for linux guests is the storage driver which
> must be included into the initrd so the image can mount the root
> filesystem.  And the firmware, bios vs. uefi is more critical than
> pc vs. q35.
> 
> > That said I'm not really convinced that using the qcow2 headers is
> > a good plan. We have many disk image formats in common use, qcow2
> > is just one. Even if the user provides the image in qcow2 format,
> > that doesn't mean that mgmt apps actually store the qcow2 file.
> 
> > I tend to think we'd be better looking at what we can do in the context
> > of an existing standard like OVF rather than inventing something that
> > only works with qcow2. I think it would need to be more expressive than
> > just a single list of key,value pairs for each item.
> 
> Embed OVF metadata in the qcow2 image?

I'm all for using the same standard for specifying machine hints
on both cases.

Now, is there an existing mechanism for virtual hardware hints
(not requirements) in OVF, or we have to invent one?

-- 
Eduardo