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Date:   Wed, 22 Sep 2021 09:22:52 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     "Tian, Kevin" <kevin.tian@intel.com>
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Subject: Re: [RFC 03/20] vfio: Add vfio_[un]register_device()
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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

Jason