Re: [PATCH v2 2/4] docs/system: Add vhost-user-input documentation

[Leo Yan <leo.yan@linaro.org>]

Hi Marc-André,

+ Mathieu for vhost RNG stuff.

On Tue, Nov 14, 2023 at 01:54:50PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Nov 13, 2023 at 11:04 PM Leo Yan <leo.yan@linaro.org> wrote:

[...]

> > @@ -2233,6 +2233,7 @@ L: virtio-fs@redhat.com
> >  virtio-input
> >  M: Gerd Hoffmann <kraxel@redhat.com>
> >  S: Odd Fixes
> > +F: docs/system/devices/vhost-user-input.rst
> >  F: hw/input/vhost-user-input.c
> >  F: hw/input/virtio-input*.c
> >  F: include/hw/virtio/virtio-input.h
> > diff --git a/docs/system/devices/vhost-user-input.rst b/docs/system/devices/vhost-user-input.rst
> 
> You need to include the file in the toctree, in docs/system/device-emulation.rst

Will update the toctree in next version.

[...]

> > +The QEMU invocation needs to create a chardev socket to communicate with the
> > +backend daemon and share memory with the guest over a memfd.
> > +
> > +::
> > +
> > +  host# qemu-system                                                            \
> > +      -chardev socket,path=/tmp/input.sock,id=mouse0                           \
> > +      -device vhost-user-input-pci,chardev=mouse0                              \
> > +      -m 4096                                                                  \
> > +      -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on    \
> > +      -numa node,memdev=mem
> 
> 
> Well, this is not a memfd. This is taken from vhost-user-rng.rst, and
> should probably be adjusted there too.

Yeah, I copied from vhost-user-rng.rst.

To be easier for our life, I will firstly fix this patch for this part,
later we can consider to update vhost-user-rng.rst in a separate patch.
Looped in Mathieu to be awared.

> It needs shared memory, memory-backend-file can provide it and is
> generally more available than memfd, although memfd should be
> preferred as it offers some extra security guarantees. There is
> already some explanations in vhost-user.rst, maybe we should just add
> extra links.

I will update the doc as:

"The QEMU invocation needs to create a chardev socket to communicate with the
backend daemon and access the VirtIO queues with the guest over the
:ref:`_shared_memory_object`."

Thanks,
Leo