Re: [Qemu-devel] [RFC PATCH] vl: only display available accelerators

[Eduardo Habkost <ehabkost@redhat.com>]

On Wed, Nov 08, 2017 at 01:21:33PM -0300, Philippe Mathieu-Daudé wrote:
> On 11/08/2017 10:28 AM, Daniel P. Berrange wrote:
> > On Mon, Oct 30, 2017 at 09:20:29AM +0100, Eduardo Habkost wrote:
> >> On Mon, Oct 30, 2017 at 01:00:56AM -0300, Philippe Mathieu-Daudé wrote:
> >>> examples configuring with '--enable-kvm --disable-tcg'
> >>>
> >>> - before
> >>>
> >>>   $ qemu-system-x86_64 -accel help
> >>>   Possible accelerators: kvm, xen, hax, tcg
> >>>
> >>>   $ qemu-system-x86_64 -accel tcg
> >>>   qemu-system-x86_64: -machine accel=tcg: No accelerator found
> >>>
> >>>   # qemu-system-x86_64 -accel hax
> >>>   qemu-system-x86_64: -machine accel=hax: No accelerator found
> >>>
> >>>   # qemu-system-x86_64 -accel xen
> >>>   xencall: error: Could not obtain handle on privileged command interface: No such file or directory
> >>>   xen be core: xen be core: can't open xen interface
> >>>   can't open xen interface
> >>>   qemu-system-x86_64: failed to initialize Xen: Operation not permitted
> >>>
> >>> - after
> >>>
> >>>   $ qemu-system-x86_64 -accel help
> >>>   Possible accelerators: kvm
> >>>
> >>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> >>> ---
> >>> RFC because:
> >>>     - I don't think this is the nicest way, too much #ifdef'fery in main()
> >>
> >> I suggest using object_class_get_list(TYPE_ACCEL, false).
> > 
> > And check the result of the available() method on the returned classes
> > too, to filter the results.
> 
> Good idea! I'll use that.

It looks like QTest is the only accelerator that implements
->available(), and its return value is a build-time constant that
depends only on CONFIG_POSIX.

I wonder why we don't simply avoid compiling the qtest class if
CONFIG_POSIX is unset, making the ->available() method
unnecessary.

-- 
Eduardo