IB: start documenting device capabilities

Just IB_DEVICE_LOCAL_DMA_LKEY and IB_DEVICE_MEM_MGT_EXTENSIONS for now
as I'm most familar with those.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagig@mellanox.com>
Reviewed-By: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index 368fc22f30f191548aebc398691daed8ee19d39f..f06ce80f12e3e795b6790a67568333c5780e2341 100644 (file)
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -162,6 +162,14 @@ enum ib_device_cap_flags {
        IB_DEVICE_RC_RNR_NAK_GEN        = (1<<12),
        IB_DEVICE_SRQ_RESIZE            = (1<<13),
        IB_DEVICE_N_NOTIFY_CQ           = (1<<14),
+
+       /*
+        * This device supports a per-device lkey or stag that can be
+        * used without performing a memory registration for the local
+        * memory.  Note that ULPs should never check this flag, but
+        * instead of use the local_dma_lkey flag in the ib_pd structure,
+        * which will always contain a usable lkey.
+        */
        IB_DEVICE_LOCAL_DMA_LKEY        = (1<<15),
        IB_DEVICE_RESERVED              = (1<<16), /* old SEND_W_INV */
        IB_DEVICE_MEM_WINDOW            = (1<<17),
@@ -175,6 +183,16 @@ enum ib_device_cap_flags {
        IB_DEVICE_UD_IP_CSUM            = (1<<18),
        IB_DEVICE_UD_TSO                = (1<<19),
        IB_DEVICE_XRC                   = (1<<20),
+
+       /*
+        * This device supports the IB "base memory management extension",
+        * which includes support for fast registrations (IB_WR_REG_MR,
+        * IB_WR_LOCAL_INV and IB_WR_SEND_WITH_INV verbs).  This flag should
+        * also be set by any iWarp device which must support FRs to comply
+        * to the iWarp verbs spec.  iWarp devices also support the
+        * IB_WR_RDMA_READ_WITH_INV verb for RDMA READs that invalidate the
+        * stag.
+        */
        IB_DEVICE_MEM_MGT_EXTENSIONS    = (1<<21),
        IB_DEVICE_BLOCK_MULTICAST_LOOPBACK = (1<<22),
        IB_DEVICE_MEM_WINDOW_TYPE_2A    = (1<<23),