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

[Markus Armbruster]

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".