[ofa-general] Re: [PATCH] for-2.6.23 ib/umad: add partition support

[Roland Dreier]

 > The only question is what happens with apps which enable the pkey index
 > mode but run on an older kernel which does not support this. They would
 > get an error back (-ENOIOCTLCMD) from user_mad. They could either error
 > out on this or continue on depending on what the app wants to do.

Yes, but I think that is purely up to the application.  Userspace
knows about the new interface, the kernel doesn't, and the application
has to decide how important the pkey_index stuff is.

Given that we don't have a time machine (so the behavior of old
kernels is frozen) I don't see anything we can do to make this any better.

 - R.