On 11/10/2015 6:51 AM, Yann Droneaud wrote:
Le mardi 10 novembre 2015 à 12:44 +0200, Sagi Grimberg a écrit :
Also, set rdma_read_access_flags in the relevant device drivers:
mlx4, mlx5, qib, ocrdma, nes: IB_ACCESS_LOCAL_WRITE
cxgb3, cxgb4, hfi: IB_ACCESS_LOCAL_WRITE | IB_ACCESS_REMOTE_WRITE
Why were those hw providers not modified to
enforce IB_ACCESS_REMOTE_WRITE when needed, instead of asking users to
set it for them ?
Because the Linux verbs don't tell the driver whether the registration
is for an RDMA Read sink buffer.
Sagi, the Windows NDKPI has an NDK_MR_FLAG_RDMA_READ_SINK attribute
which the upper layer can use to convey this information, I've mentioned
it here before.
https://msdn.microsoft.com/en-us/library/windows/hardware/hh439908(v=vs.85).aspx
When this approach is used, the upper layer doesn't have to be aware
at all of the lower layer's details.
Tom.
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