Re: [PATCH] qemu-options.hx: 9p: clarify -virtfs vs. -fsdev

[Cornelia Huck]

On Tue, 31 Mar 2020 18:05:08 +0200
Markus Armbruster <address@hidden> wrote:

> Christian Schoenebeck <address@hidden> writes:
> 
> > On Dienstag, 31. März 2020 17:27:27 CEST Cornelia Huck wrote:  
> >> > diff --git a/qemu-options.hx b/qemu-options.hx
> >> > index 962a5ebaa6..fd3830c6cd 100644
> >> > --- a/qemu-options.hx
> >> > +++ b/qemu-options.hx
> >> > @@ -1542,9 +1542,17 @@ SRST
> >> > 
> >> >  ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag  
> >> >  [,writeout=writeout][,readonly]``>    
> >> >    \
> >> >  
> >> >  ``-virtfs synth,mount_tag=mount_tag``
> >> > 
> >> > -    Define a new filesystem device and expose it to the guest using a
> >> > -    virtio-9p-device. The general form of a Virtual File system
> >> > -    pass-through options are:
> >> > +    Define a new virtual filesystem device and expose it to the guest
> >> > using +    a virtio-9p-device (a.k.a. 9pfs), which essentially means that
> >> > a certain +    directory on host is made directly accessible by guest as
> >> > a pass-through +    file system by using the 9P network protocol for
> >> > communication between +    host and guests, if desired even accessible,
> >> > shared by several guests +    simultaniously.
> >> > +
> >> > +    Note that ``-virtfs`` is actually just a convenience shortcut for 
> >> > its
> >> > +    generalized form ``-fsdev -device virtio-9p-pci``.  
> >> 
> >> Huh. This prompted me to try this on s390, and it actually creates a
> >> virtio-9p-pci device there as well, not a virtio-9p-ccw device. A bit
> >> surprising; but I don't see 9p used much (if at all) on s390 anyway.  
> >
> > Yeah, "virtio-9p-pci" is currently hard coded in softmmu/vl.c [line 3352]:
> > https://github.com/qemu/qemu/blob/17083d6d1e0635371418c26b613a6fa68d392f49/softmmu/vl.c#L3352
> >   
> 
> Should it be "virtio-9p" instead?  It's an alias for "virtio-9p-pci",
> except for s390x, where it's an alias for "virtio-9p-ccw".

Seems like a reasonable change (although I'm not sure it matters too
much).