Re: [Qemu-trivial] [Qemu-devel] [RFC PATCH 4/4] qemu-options: Do not show -enable-kvm and -enable-hax in the docs anymore

[Eduardo Habkost]

On Fri, Jun 22, 2018 at 09:19:56PM +0200, Thomas Huth wrote:
> On 22.06.2018 20:11, Eduardo Habkost wrote:
> > On Tue, Jun 19, 2018 at 06:16:33PM +0200, Paolo Bonzini wrote:
> >> On 19/06/2018 17:15, Cornelia Huck wrote:
> >>>> Why does a user have to know how to enable KVM?  Oh, because our default
> >>>> is "run this guest much slower than necessary".  Great!
> >>> Should we try again to default to a better accelerator, if possible? I
> >>> don't quite recall why we didn't do so the last time that came up...
> >>> was it tests?
> >>
> >> My plan was to create qemu-{kvm,hax,hvf,whpx} binaries that default to a
> >> better accelerator, and leave qemu-system-* as defaulting to TCG.  This
> >> matches what distributions already do.
> > 
> > Why is this better than using KVM by default if it's available?
> 
> The answer is (as almost always): Compatibility with migration. Nobody
> dares to sacrifice that chicken :-(

We can now kill it if we announce the feature as deprecated a
couple of releases in advance.

If we declare that compatibility when the accelerator is omitted
is deprecated in 3.0, in QEMU 3.3 we will be free to choose a
different default accelerator.

-- 
Eduardo