Re: [PATCH] exit if we fail to initialize kvm

[Glauber Costa <glommer@redhat.com>]

On Wed, Jul 29, 2009 at 04:43:11PM +0200, Jan Kiszka wrote:
> Alexander Graf wrote:
> > Avi Kivity wrote:
> >> On 07/29/2009 01:17 PM, Jan Kiszka wrote:
> >>> I just wonder now if/when qemu-kvm will switch over to the
> >>> kvm-by-default-off policy of upstream?
> >>>    
> >> That will surely inconvenience/surprise a lot of users.
> >>
> >> A migration path could be:
> >>
> >> - add -accel
> >> - start warning when -accel is not used, encouraging people to use -accel
> >> - time passes
> >> - switch default to tcg (maybe unless invoked with kvm in argv[0])
> >> - time passes
> >> - remove warning
> >>
> > 
> > I would prefer:
> > 
> > - add -accel (default to kvm)
> > - give a message to use -accel tcg when the user wants tcg
> > - make -accel go kvm,kqemu,tcg in qemu upstream
> 
> Upstream just dropped the behavior '-accel kqemu,tcg', so I'm not sure
> if this is desired to return (though I'm surely not comparing kvm to
> kqemu here).
> 
> > - have distros / management tools decide which accel they like
> 
> That's likely the key: explicit -accel.
While I do understand the value of backwards compatibility, we did change
behaviour of a number of things in the past. Example: "qemu" would print a help message,
and now it runs without any disks. It changed people's script already.

It should probably be okay to drop all kvm,kqemu,whatever-related options in favour
of accel if we are doing this in a release boundary.