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Diffstat (limited to 'Documentation/infiniband/user_mad.txt')
| -rw-r--r-- | Documentation/infiniband/user_mad.txt | 148 |
1 files changed, 0 insertions, 148 deletions
diff --git a/Documentation/infiniband/user_mad.txt b/Documentation/infiniband/user_mad.txt deleted file mode 100644 index 8a366959f5c..00000000000 --- a/Documentation/infiniband/user_mad.txt +++ /dev/null @@ -1,148 +0,0 @@ -USERSPACE MAD ACCESS - -Device files - - Each port of each InfiniBand device has a "umad" device and an - "issm" device attached. For example, a two-port HCA will have two - umad devices and two issm devices, while a switch will have one - device of each type (for switch port 0). - -Creating MAD agents - - A MAD agent can be created by filling in a struct ib_user_mad_reg_req - and then calling the IB_USER_MAD_REGISTER_AGENT ioctl on a file - descriptor for the appropriate device file. If the registration - request succeeds, a 32-bit id will be returned in the structure. - For example: - - struct ib_user_mad_reg_req req = { /* ... */ }; - ret = ioctl(fd, IB_USER_MAD_REGISTER_AGENT, (char *) &req); - if (!ret) - my_agent = req.id; - else - perror("agent register"); - - Agents can be unregistered with the IB_USER_MAD_UNREGISTER_AGENT - ioctl. Also, all agents registered through a file descriptor will - be unregistered when the descriptor is closed. - -Receiving MADs - - 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 - example, the remote LID will be in mad.lid. - - If a send times out, a receive will be generated with mad.status set - to ETIMEDOUT. Otherwise when a MAD has been successfully received, - mad.status will be 0. - - poll()/select() may be used to wait until a MAD can be read. - -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. The send side does support - RMPP so arbitrary length MAD can be sent. For example: - - struct ib_user_mad *mad; - - mad = malloc(sizeof *mad + mad_length); - - /* fill in mad->data */ - - 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 + mad_length); - if (ret != sizeof *mad + mad_length) - perror("write"); - -Transaction IDs - - Users of the umad devices can use the lower 32 bits of the - transaction ID field (that is, the least significant half of the - field in network byte order) in MADs being sent to match - request/response pairs. The upper 32 bits are reserved for use by - the kernel and will be overwritten before a MAD is sent. - -P_Key Index Handling - - The old ib_umad interface did not allow setting the P_Key index for - MADs that are sent and did not provide a way for obtaining the P_Key - index of received MADs. A new layout for struct ib_user_mad_hdr - with a pkey_index member has been defined; however, to preserve - binary compatibility with older applications, this new layout will - not be used unless the IB_USER_MAD_ENABLE_PKEY ioctl is called - before a file descriptor is used for anything else. - - In September 2008, the IB_USER_MAD_ABI_VERSION will be incremented - to 6, the new layout of struct ib_user_mad_hdr will be used by - default, and the IB_USER_MAD_ENABLE_PKEY ioctl will be removed. - -Setting IsSM Capability Bit - - To set the IsSM capability bit for a port, simply open the - corresponding issm device file. If the IsSM bit is already set, - then the open call will block until the bit is cleared (or return - immediately with errno set to EAGAIN if the O_NONBLOCK flag is - passed to open()). The IsSM bit will be cleared when the issm file - is closed. No read, write or other operations can be performed on - the issm file. - -/dev files - - To create the appropriate character device files automatically with - udev, a rule like - - KERNEL=="umad*", NAME="infiniband/%k" - KERNEL=="issm*", NAME="infiniband/%k" - - can be used. This will create device nodes named - - /dev/infiniband/umad0 - /dev/infiniband/issm0 - - for the first port, and so on. The InfiniBand device and port - associated with these devices can be determined from the files - - /sys/class/infiniband_mad/umad0/ibdev - /sys/class/infiniband_mad/umad0/port - - and - - /sys/class/infiniband_mad/issm0/ibdev - /sys/class/infiniband_mad/issm0/port |