X-Git-Url: http://drtracing.org/?a=blobdiff_plain;f=Documentation%2Fntb.txt;h=1d9bbabb6c79abb04259b78481f7304abacbaccc;hb=5c755fe142b421d295e7dd64a9833c12abbfd28e;hp=9d46dc9712a8736bfdabe0e2ee55b5e60fcd524a;hpb=a1bd3baeb2f18b2b3d0f98ce5fdaa725149b950b;p=deliverable%2Flinux.git diff --git a/Documentation/ntb.txt b/Documentation/ntb.txt index 9d46dc9712a8..1d9bbabb6c79 100644 --- a/Documentation/ntb.txt +++ b/Documentation/ntb.txt @@ -26,7 +26,102 @@ as ntb hardware, or hardware drivers, are inserted and removed. The registration uses the Linux Device framework, so it should feel familiar to anyone who has written a pci driver. +### NTB Transport Client (ntb\_transport) and NTB Netdev (ntb\_netdev) + +The primary client for NTB is the Transport client, used in tandem with NTB +Netdev. These drivers function together to create a logical link to the peer, +across the ntb, to exchange packets of network data. The Transport client +establishes a logical link to the peer, and creates queue pairs to exchange +messages and data. The NTB Netdev then creates an ethernet device using a +Transport queue pair. Network data is copied between socket buffers and the +Transport queue pair buffer. The Transport client may be used for other things +besides Netdev, however no other applications have yet been written. + +### NTB Ping Pong Test Client (ntb\_pingpong) + +The Ping Pong test client serves as a demonstration to exercise the doorbell +and scratchpad registers of NTB hardware, and as an example simple NTB client. +Ping Pong enables the link when started, waits for the NTB link to come up, and +then proceeds to read and write the doorbell scratchpad registers of the NTB. +The peers interrupt each other using a bit mask of doorbell bits, which is +shifted by one in each round, to test the behavior of multiple doorbell bits +and interrupt vectors. The Ping Pong driver also reads the first local +scratchpad, and writes the value plus one to the first peer scratchpad, each +round before writing the peer doorbell register. + +Module Parameters: + +* unsafe - Some hardware has known issues with scratchpad and doorbell + registers. By default, Ping Pong will not attempt to exercise such + hardware. You may override this behavior at your own risk by setting + unsafe=1. +* delay\_ms - Specify the delay between receiving a doorbell + interrupt event and setting the peer doorbell register for the next + round. +* init\_db - Specify the doorbell bits to start new series of rounds. A new + series begins once all the doorbell bits have been shifted out of + range. +* dyndbg - It is suggested to specify dyndbg=+p when loading this module, and + then to observe debugging output on the console. + +### NTB Tool Test Client (ntb\_tool) + +The Tool test client serves for debugging, primarily, ntb hardware and drivers. +The Tool provides access through debugfs for reading, setting, and clearing the +NTB doorbell, and reading and writing scratchpads. + +The Tool does not currently have any module parameters. + +Debugfs Files: + +* *debugfs*/ntb\_tool/*hw*/ - A directory in debugfs will be created for each + NTB device probed by the tool. This directory is shortened to *hw* + below. +* *hw*/db - This file is used to read, set, and clear the local doorbell. Not + all operations may be supported by all hardware. To read the doorbell, + read the file. To set the doorbell, write `s` followed by the bits to + set (eg: `echo 's 0x0101' > db`). To clear the doorbell, write `c` + followed by the bits to clear. +* *hw*/mask - This file is used to read, set, and clear the local doorbell mask. + See *db* for details. +* *hw*/peer\_db - This file is used to read, set, and clear the peer doorbell. + See *db* for details. +* *hw*/peer\_mask - This file is used to read, set, and clear the peer doorbell + mask. See *db* for details. +* *hw*/spad - This file is used to read and write local scratchpads. To read + the values of all scratchpads, read the file. To write values, write a + series of pairs of scratchpad number and value + (eg: `echo '4 0x123 7 0xabc' > spad` + # to set scratchpads `4` and `7` to `0x123` and `0xabc`, respectively). +* *hw*/peer\_spad - This file is used to read and write peer scratchpads. See + *spad* for details. + ## NTB Hardware Drivers NTB hardware drivers should register devices with the NTB core driver. After registering, clients probe and remove functions will be called. + +### NTB Intel Hardware Driver (ntb\_hw\_intel) + +The Intel hardware driver supports NTB on Xeon and Atom CPUs. + +Module Parameters: + +* b2b\_mw\_idx - If the peer ntb is to be accessed via a memory window, then use + this memory window to access the peer ntb. A value of zero or positive + starts from the first mw idx, and a negative value starts from the last + mw idx. Both sides MUST set the same value here! The default value is + `-1`. +* b2b\_mw\_share - If the peer ntb is to be accessed via a memory window, and if + the memory window is large enough, still allow the client to use the + second half of the memory window for address translation to the peer. +* xeon\_b2b\_usd\_bar2\_addr64 - If using B2B topology on Xeon hardware, use + this 64 bit address on the bus between the NTB devices for the window + at BAR2, on the upstream side of the link. +* xeon\_b2b\_usd\_bar4\_addr64 - See *xeon\_b2b\_bar2\_addr64*. +* xeon\_b2b\_usd\_bar4\_addr32 - See *xeon\_b2b\_bar2\_addr64*. +* xeon\_b2b\_usd\_bar5\_addr32 - See *xeon\_b2b\_bar2\_addr64*. +* xeon\_b2b\_dsd\_bar2\_addr64 - See *xeon\_b2b\_bar2\_addr64*. +* xeon\_b2b\_dsd\_bar4\_addr64 - See *xeon\_b2b\_bar2\_addr64*. +* xeon\_b2b\_dsd\_bar4\_addr32 - See *xeon\_b2b\_bar2\_addr64*. +* xeon\_b2b\_dsd\_bar5\_addr32 - See *xeon\_b2b\_bar2\_addr64*.