[openib-general] failure to create an FMR mapping 1K pages on memfree

[Roland Dreier]

 > I have got a report on failure to create FMR mapping 1K pages (that is
 > 4MB) on memfree.
 >
 > I don't have the exact details (ie if Arbel/Sinai / what FW  / etc)
 > nor which exact check fails in
 > mthca_fmr_alloc, but what's clear is that the latter function returns
 > -ENOMEM when attr.max_pages is 1024 and it works fine when
 > attr.max_pages is 256.
 >
 > Is this failure clear to you? if yes, does a HW or FW limit is being
 > hit or its a driver design issue?

Is it really returning -ENOMEM?  It seems much more likely that you
are hitting the code

	/* For Arbel, all MTTs must fit in the same page. */
	if (mthca_is_memfree(dev) &&
	    mr->attr.max_pages * sizeof *mr->mem.arbel.mtts > PAGE_SIZE)
		return -EINVAL;

I guess you could call this limit a driver design issue.

 - R.