Ah, the usual "ioctls are ugly, go away".
It could be done via sysfs:
$ cat /sys/.../msix/max-interrupts
256
$ echo 4> /sys/.../msix/allocate
$ # subdirectories 0 1 2 3 magically appear
$ # bind fd 13 to msix
$ echo 13> /sys/.../msix/2/bind-fd
$ # from now on, msix interrupt 2 will call eventfd_signal() on fd 13
Call me old fashioned, but I prefer ioctls.
Good point. iiuc, the goal relative to ioctls in UIO was to not have
device drivers creating their own device-specific ABIs and drivers
that are just massive switch statements. Having ioctls that support
functions for UIO in general, such as pairing msi vectors to eventfds,
does not go against that goal.