diff options
Diffstat (limited to 'Documentation/infiniband')
| -rw-r--r-- | Documentation/infiniband/user_mad.txt | 53 |
1 files changed, 40 insertions, 13 deletions
diff --git a/Documentation/infiniband/user_mad.txt b/Documentation/infiniband/user_mad.txt index cae0c83f1ee..750fe5e80eb 100644 --- a/Documentation/infiniband/user_mad.txt +++ b/Documentation/infiniband/user_mad.txt @@ -28,13 +28,37 @@ Creating MAD agents Receiving MADs - MADs are received using read(). The buffer passed to read() must be - large enough to hold at least one struct ib_user_mad. For example: - - struct ib_user_mad mad; - ret = read(fd, &mad, sizeof mad); - if (ret != sizeof mad) + MADs are received using read(). The receive side now supports + RMPP. The buffer passed to read() must be at least one + struct ib_user_mad + 256 bytes. For example: + + If the buffer passed is not large enough to hold the received + MAD (RMPP), the errno is set to ENOSPC and the length of the + buffer needed is set in mad.length. + + Example for normal MAD (non RMPP) reads: + struct ib_user_mad *mad; + mad = malloc(sizeof *mad + 256); + ret = read(fd, mad, sizeof *mad + 256); + if (ret != sizeof mad + 256) { + perror("read"); + free(mad); + } + + Example for RMPP reads: + struct ib_user_mad *mad; + mad = malloc(sizeof *mad + 256); + ret = read(fd, mad, sizeof *mad + 256); + if (ret == -ENOSPC)) { + length = mad.length; + free(mad); + mad = malloc(sizeof *mad + length); + ret = read(fd, mad, sizeof *mad + length); + } + if (ret < 0) { perror("read"); + free(mad); + } In addition to the actual MAD contents, the other struct ib_user_mad fields will be filled in with information on the received MAD. For @@ -50,18 +74,21 @@ Sending MADs MADs are sent using write(). The agent ID for sending should be filled into the id field of the MAD, the destination LID should be - filled into the lid field, and so on. For example: + filled into the lid field, and so on. The send side does support + RMPP so arbitrary length MAD can be sent. For example: + + struct ib_user_mad *mad; - struct ib_user_mad mad; + mad = malloc(sizeof *mad + mad_length); - /* fill in mad.data */ + /* fill in mad->data */ - mad.id = my_agent; /* req.id from agent registration */ - mad.lid = my_dest; /* in network byte order... */ + mad->hdr.id = my_agent; /* req.id from agent registration */ + mad->hdr.lid = my_dest; /* in network byte order... */ /* etc. */ - ret = write(fd, &mad, sizeof mad); - if (ret != sizeof mad) + ret = write(fd, &mad, sizeof *mad + mad_length); + if (ret != sizeof *mad + mad_length) perror("write"); Setting IsSM Capability Bit |