[openib-general] fmr question

[Roland Dreier]

    Steve> Lets say a FMR is allocated with a map count of 4.  And the
    Steve> FMR is mapped 4 times, then unmapped.  Are the underlying
    Steve> MRs still valid and setup for RDMA from the HW perspective?
    Steve> Or are they marked "INVALID" as part of unmapping?  IE: Do
    Steve> they remain valid up to unmap or up to dealloc of the FMR

They are not valid after the unmap operation.  In fact, old mappings
are probably not valid after the FMR is remapped; the issue for
Mellanox hardware is that the old mapping might still be hanging
around in an internal cache somewhere.  However the unmap_fmr
operation flushes all these caches, so all old mappings are gone after
an FMR is unmapped.

 - R.