"Michael S. Tsirkin" <m...@redhat.com> wrote: > On Thu, Mar 18, 2010 at 09:59:03AM +0100, Juan Quintela wrote: >> "Michael S. Tsirkin" <m...@redhat.com> wrote: >> > On Thu, Mar 18, 2010 at 09:26:10AM +0100, Juan Quintela wrote: >> >> "Michael S. Tsirkin" <m...@redhat.com> wrote: >> >> > On Tue, Mar 16, 2010 at 07:51:22PM +0100, Juan Quintela wrote: >> >> >> We already do the test for msix on the caller, just use that test >> >> >> >> >> >> Signed-off-by: Juan Quintela <quint...@redhat.com> >> >> > >> >> > NAK >> >> > >> >> > I think we are better off not making assumptions >> >> > about caller behaviour in msix.c, virtio >> >> > will not be the only user forever. >> >> >> >> That makes migration testing more difficult. Basically we are testing >> >> if we are using msix in two places. Obvious thing is: >> >> - we don't test in msix_save() if msix is used. >> >> - we don't test it in virtio_pci_save_config() >> >> >> >> I don't care if it is one way or another, but requiring to check it in >> >> the caller and the callee is a bit too much for me. >> >> >> >> Later, Juan. >> > >> > msix does not require the check in the caller, by design it is >> > safe to call msix_save when msix is not present. >> >> look at it, it requires to test msix support for other things, which >> amount to the same thing :( >> >> Later, Juan. > > Yes, but it does not have to be the only user. We'll have at least pci > assignment use it, at some point. IOW, msix tries to present an API > that is safe to use, and checks capability so we do not crash if it's > not there. virtio happens to need the same test for its own reasons > (vmsave format backwards compatibility). > > We could optimize the test if we cared about speed here, but we don't > ...
It makes my vmstate work more complex, because this is the only user that calls a vvnmstat* and uses _nothing_ of it. rest of users are something like: VMSTATE(...., test_function); on the caller side. As virtio already needs to know msix use for other reasons, I really expect that anything else that uses msix would need the same test for the same reason. Later, Juan.
