"Michael S. Tsirkin" <mst@xxxxxxxxxx> writes: > On Tue, Sep 04, 2012 at 06:58:47PM +0200, Sjur Brændeland wrote: >> Hi Michael, >> >> > Exactly. Though if we just fail load it will be much less code. >> > >> > Generally, using a feature bit for this is a bit of a problem though: >> > normally driver is expected to be able to simply ignore >> > a feature bit. In this case driver is required to >> > do something so a feature bit is not a good fit. >> > I am not sure what the right thing to do is. >> >> I see - so in order to avoid the binding between driver and device >> there are two options I guess. Either make virtio_dev_match() or >> virtcons_probe() fail. Neither of them seems like the obvious choice. >> >> Maybe adding a check for VIRTIO_CONSOLE_F_DMA_MEM match >> between device and driver in virtcons_probe() is the lesser evil? >> >> Regards, >> Sjur > > A simplest thing to do is change dev id. rusty? For generic usage, this is correct. But my opinion is that fallback on feature non-ack is quality-of-implementation issue: great to have, but there are cases where you just want to fail with "you're too old". And in this case, an old system simply will never work. So it's a question of how graceful the failure is. Can your userspace loader can refuse to proceed if the driver doesn't ack the bits? If so, it's simpler than a whole new ID. Cheers, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
