Re: [Qemu-devel] [PATCH 1/2] accel: allows to select the "best" accelerator

[Paolo Bonzini]

On 04/10/2016 13:30, Laurent Vivier wrote:
> But sometime, user wants to use a real accelerator without knowing
> if he really can, with, for instance accel=kvm:tcg.
> In this case, and if the accelerator is not available we
> have a noisy "XXX accelerator not found".
> 
> By allowing the user to ask the "best" accelerator for the given
> target, we can avoid this problem.
> 
> This patch introduces a new parameter for the "accel" property, the
> "best" keyword.
> 
> You can ask to use the best accelerator with "-M accel=best",
> or if you want to use your favorite accelerator and if it is not
> available, the best one, you can use, for instance
> "-M accel=kvm:best".

I don't think there's a single definition of a "best" accelerator.  For
example, some "-cpu" features may be available only with TCG.  In that
case, "kvm:tcg" has a clear meaning ("kvm" if it exists, otherwise
"tcg") but "best" doesn't.

I agree with Daniel that unit tests should use "tcg" exclusively, at
least as a default.

Paolo