Re: [Qemu-devel] change x86 default machine type to Q35?

[Eduardo Habkost]

On Wed, Jul 12, 2017 at 09:39:39AM +0300, Marcel Apfelbaum wrote:
> On 11/07/2017 17:47, Paolo Bonzini wrote:
> > On 11/07/2017 16:42, Kevin Wolf wrote:
> > > > >   Concerning QEMU, could we maybe simply emit a warning a la
> > > > > 
> > > > >   "you did not specify a machine type with the -M option, so you are
> > > > >    currently running the the 'pc' machine type. Please note that
> > > > > future
> > > > >    versions of QEMU might use the 'q35' machine type instead. If you
> > > > >    require the 'pc' machine type for your setting, then please specify
> > > > >    it with the -M option."
> > > > Warnings tend to get ignored until things are actually break, so I
> > > > don't think this helps much.  I think simply not having a default
> > > > machine type (as already suggested elsewhere in this thread) is the
> > > > best way to deal with this.
> > > I would absolutely hate this. One of the nice things about qemu has
> > > always been that 'qemu disk.img' is enough to start a simple VM. You
> > > only need to touch any other options for things you care about. I
> > > wouldn't want to give this up.
> > 
> > I agree.  Don't change anything, leave "-M pc" aside, and let libosinfo
> > pick q35 for newer guests.
> > 
> 
> Hi Paolo,
> 
> While I do think it would be a good step moving forward, I am not
> convinced is "enough" to get more users using it. More so, a low
> level bug in upper layers (e.g. Open stack) will lead to difficulty
> to debug and result in the same "The machine is not steady enough,
> it doesn't worth the effort, let's move back to pc", or even
> frustration of the people that really need Q35.

I guess not being enough depends on which users we want to
affect.  People who run QEMU from the command-line don't get a
virtio drive or a modern CPU model chosen by default, either.  Is
the choice of machine-type different?  Why?

> [...]

-- 
Eduardo