Re: [PATCH v3 4/4] docs: vhost-user: add subsection for non-Linux platforms

[Sergio Lopez]

On Fri, Mar 04, 2022 at 05:35:01AM -0500, Michael S. Tsirkin wrote:
> On Thu, Mar 03, 2022 at 12:59:11PM +0100, Sergio Lopez wrote:
> > Add a section explaining how vhost-user is supported on platforms
> > other than Linux.
> > 
> > Signed-off-by: Sergio Lopez <slp@redhat.com>
> > ---
> >  docs/interop/vhost-user.rst | 18 ++++++++++++++++++
> >  1 file changed, 18 insertions(+)
> > 
> > diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
> > index edc3ad84a3..590a626b92 100644
> > --- a/docs/interop/vhost-user.rst
> > +++ b/docs/interop/vhost-user.rst
> > @@ -38,6 +38,24 @@ conventions <backend_conventions>`.
> >  *Master* and *slave* can be either a client (i.e. connecting) or
> >  server (listening) in the socket communication.
> >  
> > +Support for platforms other than Linux
> 
> 
> It's not just Linux - any platform without eventfd.
> 
> So I think we should have a section explaining that whereever
> spec says eventfd it can be a pipe if system does not
> support creating eventfd.

I'm confused. This is exactly what this subsection intends to do...

Thanks,
Sergio.

> > +--------------------------------------
> > +
> > +While vhost-user was initially developed targeting Linux, nowadays is
> > +supported on any platform that provides the following features:
> > +
> > +- The ability to share a mapping injected into the guest between
> > +  multiple processes, so both QEMU and the vhost-user daemon servicing
> > +  the device can access simultaneously the memory regions containing
> > +  the virtqueues and the data associated with each request.
> > +
> > +- AF_UNIX sockets with SCM_RIGHTS, so QEMU can communicate with the
> > +  vhost-user daemon and send it file descriptors when needed.
> > +
> > +- Either eventfd or pipe/pipe2. On platforms where eventfd is not
> > +  available, QEMU will automatically fallback to pipe2 or, as a last
> > +  resort, pipe.
> > +
> >  Message Specification
> >  =====================
> >  
> > -- 
> > 2.35.1
>

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