[ofa-general] Zero byte rdma read causes REM_OP_ERROR

[Jack Morgenstein]

On Sunday 27 January 2008 15:06, Dotan Barak wrote:
> Rajouri Jammu wrote:
> > I'm using rdma_cm and I don't set the qp_access_flags explicitly.
> >
> > I presume they are set correctly since non-zero length rdma reads 
> > complete successfully. I have also verified the data.
> >
> > the only place I set the privileges is when registering the memory 
> > region and I have them set at
> > IBV_ACCESS_LOCAL_WRITE, _REMOTE_READ and _REMOTE_WRITE

To send perform a zero-byte RDMA-read/write, you should assemble a WQE with
no scatter/gather entries (see IBSPEC 1.2, volume 1, section 11.4.1.1,
table 94 -- Work Request Modifier Matrix, footnote b).  A s/g entry with its length
field = 0 is interpreted as requesting 2 gigabytes.

Is this the problem?

- Jack