[openib-general] Re: InfiniBand MAD device number request

[Roland Dreier]

    Torben> Allright, I begun looking into using the 2.6 specific
    Torben> major/minor allocations.  2.6 allows 20 bit worth of
    Torben> minors per major. I'll let you know once I know more.

As we continue our development of InfiniBand drivers, it's becoming
apparent that we will need other types of character devices in
addition to the umadN devices I sent the original request for.

It seems that using a large major (ie > 255) is a good solution, since
we have no backwards compatibility to worry about.  So I would propose
the following if it seems acceptable to you: reserve something like a
2K or 4K chunk of minors in the large major space for IB (eg
256:0...256:4095 -- of course the major isn't important if you want to
start assigning somewhere else) and assign the first 256 minors from
this range as /dev/infiniband/umad0 ... /dev/infiniband/umad255.

I know of at least two more types of character devices that we will be
requesting as the driver work is completed, and these could be
allocated from the same IB chunk.

Thanks,
  Roland