@@ -290,7 +290,8 @@ enum ibv_access_flags {
IBV_ACCESS_REMOTE_WRITE = (1<<1),
IBV_ACCESS_REMOTE_READ = (1<<2),
IBV_ACCESS_REMOTE_ATOMIC = (1<<3),
- IBV_ACCESS_MW_BIND = (1<<4)
+ IBV_ACCESS_MW_BIND = (1<<4),
+ IBV_ACCESS_GIFT = (1<<6)
};
struct ibv_pd {
@@ -34,6 +34,8 @@ describes the desired memory protection attributes; it is either 0 or the bitwis
.B IBV_ACCESS_REMOTE_ATOMIC\fR Enable Remote Atomic Operation Access (if supported)
.TP
.B IBV_ACCESS_MW_BIND\fR Enable Memory Window Binding
+.TP
+.B IBV_ACCESS_GIFT\fR This memory is a gift to the adapter: if memory is modified after registration, the local version and data seen by the adapter through this region rkey may differ
.PP
If
.B IBV_ACCESS_REMOTE_WRITE
@@ -43,6 +45,9 @@ is set, then
.B IBV_ACCESS_LOCAL_WRITE
must be set too.
.PP
+.B IBV_ACCESS_GIFT
+is only legal with remote or local read access.
+.PP
Local read access is always enabled for the MR.
.PP
.B ibv_dereg_mr()
At the moment registering an MR breaks COW. If the application does not care that adapter sees stale data (for example, it tracks writes reregisters and resends), it can use a new IBV_ACCESS_GIFT flag to prevent registration from breaking COW. The semantics are similar to that of SPLICE_F_GIFT thus the name. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- This is compiled but untested. Michael, could you please try this patch (together with the kernel patch I'm sending separately) and report whether setting this flag unbreaks overcommit for you? include/infiniband/verbs.h | 3 ++- man/ibv_reg_mr.3 | 5 +++++ 2 files changed, 7 insertions(+), 1 deletion(-)