RE: [RFC 03/20] vfio: Add vfio_[un]register_device()

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Wednesday, September 22, 2021 8:23 PM
> 
> On Wed, Sep 22, 2021 at 09:23:34AM +0000, Tian, Kevin wrote:
> 
> > > Providing an ioctl to bind to a normal VFIO container or group might
> > > allow a reasonable fallback in userspace..
> >
> > I didn't get this point though. An error in binding already allows the
> > user to fall back to the group path. Why do we need introduce another
> > ioctl to explicitly bind to container via the nongroup interface?
> 
> New userspace still needs a fallback path if it hits the 'try and
> fail'. Keeping the device FD open and just using a different ioctl to
> bind to a container/group FD, which new userspace can then obtain as a
> fallback, might be OK.
> 
> Hard to see without going through the qemu parts, so maybe just keep
> it in mind
> 

sure. will figure it out when working on the qemu part.