Re: [libvirt] [PATCH v3 libvirt 3/3] qemu: add support for MTP filesystem

On 19.08.2014 22:11, Giuseppe Scrivano wrote: > Generate the qemu command line option: > > -device 'usb-mtp,root=$SRC,desc=$TARGET' > > from the definition XML: > > <filesystem type='mount'> > <source dir='$SRC'/> > <target dir='$TARGET'/> > <model type='mtp'/> > </filesystem> > > Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1121781 > > Signed-off-by: Giuseppe Scrivano <gscrivan(a)redhat.com&gt; > ---

> + virBufferAddLit(&opt, "usb-mtp"); > + virBufferAsprintf(&opt, ",root=%s,desc=%s", fs->src, > fs->dst); Reading qemu sources the root property is called 'x-root'. And indeed domain fails to start:

usb: mtp: tag root property as experimental Reason: we don't want commit to that interface yet. Possibly the implementation will be switched over to use fsdev. Suggested-by: Paolo Bonzini <pbonzini(a)redhat.com&gt; Signed-off-by: Gerd Hoffmann <kraxel(a)redhat.com&gt; diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c index 1b51a90..384d4a5 100644 --- a/hw/usb/dev-mtp.c +++ b/hw/usb/dev-mtp.c @@ -1090,7 +1090,7 @@ static const VMStateDescription vmstate_usb_mtp = { }; static Property mtp_properties[] = { - DEFINE_PROP_STRING("root", MTPState, root), + DEFINE_PROP_STRING("x-root", MTPState, root), DEFINE_PROP_STRING("desc", MTPState, desc), DEFINE_PROP_END_OF_LIST(), }; Question that pops up immediately: do we want to commit to something that even qemu developers don't believe yet? What will happen when qemu decides to switch to 'root' attribute again? Libvirt will have to adapt which won't work with older qemus supporting 'x-root' only.