Re: [Qemu-devel] [PATCH v2] 9pfs: fix dependencies

[Greg Kurz <groug@kaod.org>]

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On Wed, 9 Aug 2017 10:27:37 +0200
Cornelia Huck <cohuck@redhat.com> wrote:

> On Wed, 9 Aug 2017 10:23:04 +0200
> Thomas Huth <thuth@redhat.com> wrote:
> 
> > On 09.08.2017 09:17, Cornelia Huck wrote:  
> > > Nothing in fsdev/ or hw/9pfs/ depends on pci; it should rather depend
> > > on CONFIG_VIRTFS and on the presence of an appropriate virtio transport
> > > device.
> > > 
> > > Let's introduce CONFIG_VIRTIO_CCW to cover s390x and check for
> > > CONFIG_VIRTFS && (CONFIG_VIRTIO_PCI || CONFIG_VIRTIO_CCW).
> > > 
> > > Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> > > ---
> > > 
> > > Changes v1->v2: drop extraneous spaces, fix build on cris
> > > 
> > > ---
> > >  default-configs/s390x-softmmu.mak | 1 +
> > >  fsdev/Makefile.objs               | 9 +++------
> > >  hw/Makefile.objs                  | 2 +-
> > >  3 files changed, 5 insertions(+), 7 deletions(-)
> > > 
> > > diff --git a/default-configs/s390x-softmmu.mak b/default-configs/s390x-softmmu.mak
> > > index 51191b77df..e4c5236ceb 100644
> > > --- a/default-configs/s390x-softmmu.mak
> > > +++ b/default-configs/s390x-softmmu.mak
> > > @@ -8,3 +8,4 @@ CONFIG_S390_FLIC=y
> > >  CONFIG_S390_FLIC_KVM=$(CONFIG_KVM)
> > >  CONFIG_VFIO_CCW=$(CONFIG_LINUX)
> > >  CONFIG_WDT_DIAG288=y
> > > +CONFIG_VIRTIO_CCW=y
> > > diff --git a/fsdev/Makefile.objs b/fsdev/Makefile.objs
> > > index 659df6e187..3d157add31 100644
> > > --- a/fsdev/Makefile.objs
> > > +++ b/fsdev/Makefile.objs
> > > @@ -1,10 +1,7 @@
> > > -ifeq ($(CONFIG_VIRTIO)$(CONFIG_VIRTFS)$(CONFIG_PCI),yyy)
> > >  # Lots of the fsdev/9pcode is pulled in by vl.c via qemu_fsdev_add.
> > > -# only pull in the actual virtio-9p device if we also enabled virtio.
> > > -common-obj-y = qemu-fsdev.o 9p-marshal.o 9p-iov-marshal.o
> > > -else
> > > -common-obj-y = qemu-fsdev-dummy.o
> > > -endif
> > > +# only pull in the actual virtio-9p device if we also enabled a virtio backend.
> > > +common-obj-$(call land,$(CONFIG_VIRTFS),$(call lor,$(CONFIG_VIRTIO_PCI),$(CONFIG_VIRTIO_CCW)))= qemu-fsdev.o 9p-marshal.o 9p-iov-marshal.o
> > > +common-obj-$(call lnot,$(call land,$(CONFIG_VIRTFS),$(call lor,$(CONFIG_VIRTIO_PCI),$(CONFIG_VIRTIO_CCW)))) = qemu-fsdev-dummy.o
> > >  common-obj-y += qemu-fsdev-opts.o qemu-fsdev-throttle.o
> > >  
> > >  # Toplevel always builds this; targets without virtio will put it in
> > > diff --git a/hw/Makefile.objs b/hw/Makefile.objs
> > > index a2c61f6b09..335f26b65e 100644
> > > --- a/hw/Makefile.objs
> > > +++ b/hw/Makefile.objs
> > > @@ -1,4 +1,4 @@
> > > -devices-dirs-$(call land, $(CONFIG_VIRTIO),$(call land,$(CONFIG_VIRTFS),$(CONFIG_PCI))) += 9pfs/
> > > +devices-dirs-$(call land,$(CONFIG_VIRTFS),$(call lor,$(CONFIG_VIRTIO_PCI),$(CONFIG_VIRTIO_CCW))) += 9pfs/
> > >  devices-dirs-$(CONFIG_SOFTMMU) += acpi/
> > >  devices-dirs-$(CONFIG_SOFTMMU) += adc/
> > >  devices-dirs-$(CONFIG_SOFTMMU) += audio/    
> > 
> > Patch should be fine now, I think...
> > 
> > But thinking about this again, I wonder whether it would be enough to
> > simply check for CONFIG_VIRTIO=y here instead. CONFIG_VIRTIO=y should be
> > sufficient to assert that there is also at least one kind of virtio
> > transport available, right?
> > Otherwise this will look really horrible as soon as somebody also tries
> > to add support for virtio-mmio here later ;-)  
> 

And virtio isn't the only transport for 9p: we also have a Xen backend,
which happen to be built because targets that support Xen also have
CONFIG_PCI I guess.

Cc'ing Stefano and Paolo who had a discussion during the review of
9p Xen backend patches:

https://patchwork.kernel.org/patch/9622325/

> Do all virtio transports have support for 9p, though? I thought it was
> only virtio-pci and virtio-ccw...

Hmm... I don't see any device-specific code in virtio-mmio.. why would it
be different for 9p than for block or net ?

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