indicating an unhandled "command". ERESTART is -1, which can lead to
confusion. ERESTART has been moved to -3 and EPASSTHROUGH has been
placed at -4. No ioctl code should now return -1 anywhere. The
ioctl() system call is now properly restartable.
8 port chip. this is used in several sbus (sparc) serial boards, as
well as an 8 port isa card from riscom. sio16 (sbus) frontend coming
shortly.
this is heavily based on the com and zs drivers.