Re: [PATCH] migration: Move populate_vfio_info() into a separate file

[Dr. David Alan Gilbert]

* Thomas Huth (thuth@redhat.com) wrote:
> On 15/03/2021 22.05, Philippe Mathieu-Daudé wrote:
> > Hi Thomas,
> > 
> > +Alex
> > 
> > On 3/15/21 8:07 PM, Thomas Huth wrote:
> > > The CONFIG_VFIO switch only works in target specific code. Since
> > > migration/migration.c is common code, the #ifdef does not have
> > > the intended behavior here. Move the related code to a separate
> > > file now which gets compiled via specific_ss instead.
> > > 
> > > Fixes: 3710586caa ("qapi: Add VFIO devices migration stats in Migration 
> > > stats")
> > > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > > ---
> > >   migration/meson.build |  3 ++-
> > >   migration/migration.c | 15 ---------------
> > >   migration/migration.h |  2 ++
> > >   migration/special.c   | 25 +++++++++++++++++++++++++
> > >   4 files changed, 29 insertions(+), 16 deletions(-)
> > >   create mode 100644 migration/special.c
> > > 
> > > diff --git a/migration/meson.build b/migration/meson.build
> > > index 9645f44005..e1f72f6ba0 100644
> > > --- a/migration/meson.build
> > > +++ b/migration/meson.build
> > > @@ -30,4 +30,5 @@ softmmu_ss.add(when: ['CONFIG_RDMA', rdma], if_true: 
> > > files('rdma.c'))
> > >   softmmu_ss.add(when: 'CONFIG_LIVE_BLOCK_MIGRATION', if_true: 
> > > files('block.c'))
> > >   softmmu_ss.add(when: zstd, if_true: files('multifd-zstd.c'))
> > > -specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: files('dirtyrate.c', 
> > > 'ram.c'))
> > > +specific_ss.add(when: 'CONFIG_SOFTMMU',
> > > +                if_true: files('dirtyrate.c', 'ram.c', 'special.c'))
> > 
> > Why not simply name this migration/vfio.c? That way we do not start
> > mixed bag of everything target specific.
> 
> I don't mind ... well, if we have other small functions there in the future
> that depend on CONFIG switches, a mixed bag file might not be such a bad
> idea instead of having lots and lots of small other files ... OTOH, if there
> is more vfio migration code in the works that might fit here, a name like
> vfio.c would be better, of course. What do the maintainers think?

Could this be done with stubs instead of an ifdef; i.e. a stub of
'vfio_mig_active' and 'vfio_mig_bytes_transferred'?

As for naming 'special' is too generic.
'vfio' is too specific (especially since most vfio code ends up under
hw/vfio)

how about migration/target.c  as something which is explicit about why
it's done that way.

Dave

>  Thomas
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK