Re: [RFC v1 01/10] roadtest: import libvhost-user from QEMU

[Vincent Whitchurch <vincent.whitchurch@axis.com>]

On Thu, Mar 24, 2022 at 02:00:10PM +0100, Johannes Berg wrote:
> On Fri, 2022-03-11 at 17:24 +0100, Vincent Whitchurch wrote:
> > Import the libvhost-user from QEMU for use in the implementation of the
> > virtio devices in the roadtest backend.
> 
> So hm, I wonder if this is the sensible thing to do?
> 
> Not that I mind importing qemu code, but:
> 
>  1) the implementation is rather complex in some places, and has support
>     for a LOT of virtio/vhost-user features that are really not needed
>     in these cases, for performance etc. It's also close to 4k LOC.

Is this really a problem given that the code is imported as-is?  The
intention is not to have to make a lot of local modifications to it in
the kernel tree.  The code is stable and presumably well-tested
upstream, and upstream maintains it as a separate library (in the QEMU
source tree though) to encourage reuse.

>  2) the implementation doesn't support time-travel mode which might come
>     in handy

True, but I don't see the external time-travel controller stuff being
too useful for the kinds of tests this framework is targeting.