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

From: Johannes Berg <johannes@sipsolutions.net>
To: Vincent Whitchurch <vincent.whitchurch@axis.com>,
	linux-kernel@vger.kernel.org
Cc: kernel@axis.com, devicetree@vger.kernel.org,
	linux-um@lists.infradead.org, shuah@kernel.org,
	brendanhiggins@google.com, linux-kselftest@vger.kernel.org,
	jic23@kernel.org, linux-iio@vger.kernel.org, lgirdwood@gmail.com,
	broonie@kernel.org, a.zummo@towertech.it,
	alexandre.belloni@bootlin.com, linux-rtc@vger.kernel.org,
	corbet@lwn.net, linux-doc@vger.kernel.org
Subject: Re: [RFC v1 01/10] roadtest: import libvhost-user from QEMU
Date: Thu, 24 Mar 2022 14:00:10 +0100	[thread overview]
Message-ID: <7f405d8d09a83954aa3411eff8b71ee687c7ec33.camel@sipsolutions.net> (raw)
In-Reply-To: <20220311162445.346685-2-vincent.whitchurch@axis.com>

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.

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

We have another implementation that might be simpler:
https://github.com/linux-test-project/usfstl/blob/main/src/vhost.c

but it probably has dependencies on other things in this library, but
vhost.c itself is only ~1k LOC. (But I need to update it, I'm sure we
have some unpublished bugfixes etc. in this code)

johannes