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-rw-r--r--Documentation/infiniband/ipoib.txt48
-rw-r--r--Documentation/infiniband/user_mad.txt4
-rw-r--r--Documentation/infiniband/user_verbs.txt4
3 files changed, 52 insertions, 4 deletions
diff --git a/Documentation/infiniband/ipoib.txt b/Documentation/infiniband/ipoib.txt
index 864ff328378..f2cfe265e83 100644
--- a/Documentation/infiniband/ipoib.txt
+++ b/Documentation/infiniband/ipoib.txt
@@ -24,6 +24,52 @@ Partitions and P_Keys
The P_Key for any interface is given by the "pkey" file, and the
main interface for a subinterface is in "parent."
+ Child interface create/delete can also be done using IPoIB's
+ rtnl_link_ops, where childs created using either way behave the same.
+
+Datagram vs Connected modes
+
+ The IPoIB driver supports two modes of operation: datagram and
+ connected. The mode is set and read through an interface's
+ /sys/class/net/<intf name>/mode file.
+
+ In datagram mode, the IB UD (Unreliable Datagram) transport is used
+ and so the interface MTU has is equal to the IB L2 MTU minus the
+ IPoIB encapsulation header (4 bytes). For example, in a typical IB
+ fabric with a 2K MTU, the IPoIB MTU will be 2048 - 4 = 2044 bytes.
+
+ In connected mode, the IB RC (Reliable Connected) transport is used.
+ Connected mode takes advantage of the connected nature of the IB
+ transport and allows an MTU up to the maximal IP packet size of 64K,
+ which reduces the number of IP packets needed for handling large UDP
+ datagrams, TCP segments, etc and increases the performance for large
+ messages.
+
+ In connected mode, the interface's UD QP is still used for multicast
+ and communication with peers that don't support connected mode. In
+ this case, RX emulation of ICMP PMTU packets is used to cause the
+ networking stack to use the smaller UD MTU for these neighbours.
+
+Stateless offloads
+
+ If the IB HW supports IPoIB stateless offloads, IPoIB advertises
+ TCP/IP checksum and/or Large Send (LSO) offloading capability to the
+ network stack.
+
+ Large Receive (LRO) offloading is also implemented and may be turned
+ on/off using ethtool calls. Currently LRO is supported only for
+ checksum offload capable devices.
+
+ Stateless offloads are supported only in datagram mode.
+
+Interrupt moderation
+
+ If the underlying IB device supports CQ event moderation, one can
+ use ethtool to set interrupt mitigation parameters and thus reduce
+ the overhead incurred by handling interrupts. The main code path of
+ IPoIB doesn't use events for TX completion signaling so only RX
+ moderation is supported.
+
Debugging Information
By compiling the IPoIB driver with CONFIG_INFINIBAND_IPOIB_DEBUG set
@@ -55,3 +101,5 @@ References
http://ietf.org/rfc/rfc4391.txt
IP over InfiniBand (IPoIB) Architecture (RFC 4392)
http://ietf.org/rfc/rfc4392.txt
+ IP over InfiniBand: Connected Mode (RFC 4755)
+ http://ietf.org/rfc/rfc4755.txt
diff --git a/Documentation/infiniband/user_mad.txt b/Documentation/infiniband/user_mad.txt
index 744687dd195..8a366959f5c 100644
--- a/Documentation/infiniband/user_mad.txt
+++ b/Documentation/infiniband/user_mad.txt
@@ -128,8 +128,8 @@ Setting IsSM Capability Bit
To create the appropriate character device files automatically with
udev, a rule like
- KERNEL="umad*", NAME="infiniband/%k"
- KERNEL="issm*", NAME="infiniband/%k"
+ KERNEL=="umad*", NAME="infiniband/%k"
+ KERNEL=="issm*", NAME="infiniband/%k"
can be used. This will create device nodes named
diff --git a/Documentation/infiniband/user_verbs.txt b/Documentation/infiniband/user_verbs.txt
index f847501e50b..e5092d696da 100644
--- a/Documentation/infiniband/user_verbs.txt
+++ b/Documentation/infiniband/user_verbs.txt
@@ -5,7 +5,7 @@ USERSPACE VERBS ACCESS
described in chapter 11 of the InfiniBand Architecture Specification.
To use the verbs, the libibverbs library, available from
- <http://openib.org/>, is required. libibverbs contains a
+ http://www.openfabrics.org/, is required. libibverbs contains a
device-independent API for using the ib_uverbs interface.
libibverbs also requires appropriate device-dependent kernel and
userspace driver for your InfiniBand hardware. For example, to use
@@ -58,7 +58,7 @@ Memory pinning
To create the appropriate character device files automatically with
udev, a rule like
- KERNEL="uverbs*", NAME="infiniband/%k"
+ KERNEL=="uverbs*", NAME="infiniband/%k"
can be used. This will create device nodes named