I forgot about the fact that the linux-gpib user-mode libraries are GPL not LGPL which might make writing a passport for NI-VISA impossible.
No, it doesn't. That's just FUD.
There are other ways, eg.
a) a tiny server application (gpl) that links the gpib lib
b) dont use that library, but talk to the kernel directly
Linux Embedded / Kernel Hacker / BSP / Driver development / Systems engineering