Re: [Qemu-devel] [PATCH v2 2/2] build-sys: do not compile net/vhost-user.c if vhost-user is disabled

[Marc-André Lureau]

Hi

----- Original Message -----
> On Fri, Jul 28, 2017 at 04:13:09PM +0200, Marc-André Lureau wrote:
> > This adds two extra #ifdef that have fairly limited conflict potential.
> > 
> > Signed-off-by: Marc-André Lureau <address@hidden>
> 
> OK but why can't we keep all ifdefs in net/ where all the
> rest of the features are ifdef'ed?
> 

We would need fallback code for vhost_user_get_* functions (see below).

> My concern is no one is going to test this weird configuration
> so we might accidentally re-enable it without noticing.
> net/net.c is where all command line play happens so
> people know a bunch of configs need to be tested when
> changing it.

I am not sure I understand your argument there. You are afraid we 'accidentaly 
re-enable' vhost-user... and forget to remove those #ifdef?

I can imagine people don't like having code clutter with #ifdef, but I think 
when it doesn't change much the logic (as in here with clean per-case 
switch/if), it is fine, ymmv.

> 
> 
> > ---
> >  hw/net/vhost_net.c | 4 ++++
> >  net/Makefile.objs  | 2 +-
> >  2 files changed, 5 insertions(+), 1 deletion(-)
> > 
> > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
> > index e037db63a3..96c4da49e4 100644
> > --- a/hw/net/vhost_net.c
> > +++ b/hw/net/vhost_net.c
> > @@ -193,6 +193,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions
> > *options)
> >          }
> >      }
> >  
> > +#ifdef CONFIG_VHOST_USER
> >      /* Set sane init value. Override when guest acks. */
> >      if (net->nc->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
> >          features = vhost_user_get_acked_features(net->nc);
> > @@ -203,6 +204,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions
> > *options)
> >              goto fail;
> >          }
> >      }
> > +#endif
> >  
> >      vhost_net_ack_features(net, features);
> >  
> > @@ -414,10 +416,12 @@ VHostNetState *get_vhost_net(NetClientState *nc)
> >      case NET_CLIENT_DRIVER_TAP:
> >          vhost_net = tap_get_vhost_net(nc);
> >          break;
> > +#ifdef CONFIG_VHOST_USER
> >      case NET_CLIENT_DRIVER_VHOST_USER:
> >          vhost_net = vhost_user_get_vhost_net(nc);
> >          assert(vhost_net);
> >          break;
> > +#endif
> >      default:
> >          break;
> >      }
> > diff --git a/net/Makefile.objs b/net/Makefile.objs
> > index 67ba5e26fb..7cac7ed1e4 100644
> > --- a/net/Makefile.objs
> > +++ b/net/Makefile.objs
> > @@ -3,7 +3,7 @@ common-obj-y += socket.o
> >  common-obj-y += dump.o
> >  common-obj-y += eth.o
> >  common-obj-$(CONFIG_L2TPV3) += l2tpv3.o
> > -common-obj-$(CONFIG_POSIX) += vhost-user.o
> > +common-obj-$(CONFIG_VHOST_USER) += vhost-user.o

So we could have something like:

+common-obj-$(not CONFIG_VHOST_USER) += vhost-user-stubs.o

?

> >  common-obj-$(CONFIG_SLIRP) += slirp.o
> >  common-obj-$(CONFIG_VDE) += vde.o
> >  common-obj-$(CONFIG_NETMAP) += netmap.o
> > --
> > 2.14.0.rc0.1.g40ca67566
>