I just spent too long tearing my (altogether far too few remaining) hair(s) out over a driver issue.
Qlogic 7240 IB card. Decent DDR unit. Our 18.104.22.168 kernel. Very stable kernel. Rock solid under ridiculous load.
OFED 1.5.2 with all the nice bug fixes etc.
And inserting/removing qib would cause all manner of kernel hiccups. So much for stability.
Well, that is, as long as the ib_ipath.ko, from the kernel RPM, was in there. Make that go away, and stuff works.
Yeah … stuff. Works.
Meanwhile, the error messages are exceedingly helpful. Like this:
Jan 25 12:27:31 n0002 kernel: [ 30.184600] Device ipath0 is missing mandatory function create_ah Jan 25 12:27:31 n0002 kernel: [ 30.184602] ib_ipath 0000:85:00.0: infinipath0: cannot register verbs: 22! Jan 25 12:27:31 n0002 kernel: [ 30.260128] ib_qib: Unable to register ipathfs