Lines Matching +full:memory +full:- +full:to +full:- +full:memory
5 NTB (Non-Transparent Bridge) is a type of PCI-Express bridge chip that connects
6 the separate memory systems of two or more computers to the same PCI-Express
8 registers and memory translation windows, as well as non common features like
9 scratchpad and message registers. Scratchpad registers are read-and-writable
13 special status bits to make sure the information isn't rewritten by another
14 peer. Doorbell registers provide a way for peers to send interrupt events.
15 Memory windows allow translated read and write access to the peer memory.
21 clients interested in NTB features to discover NTB the devices supported by
22 hardware drivers. The term "client" is used here to mean an upper layer
24 is used here to mean a driver for a specific vendor and model of NTB hardware.
32 registration uses the Linux Device framework, so it should feel familiar to
36 ----------------------------------------
38 Primary purpose of NTB is to share some peace of memory between at least two
40 mainly used to perform the proper memory window initialization. Typically
41 there are two types of memory window interfaces supported by the NTB API:
48 Memory: Local NTB Port: Peer NTB Port: Peer MMIO:
50 | dma-mapped |-ntb_mw_set_trans(addr) |
51 | memory | _v____________ | ______________
52 | (addr) |<======| MW xlat addr |<====| MW base addr |<== memory-mapped IO
53 |------------| |--------------| | |--------------|
55 So typical scenario of the first type memory window initialization looks:
56 1) allocate a memory region, 2) put translated address to NTB config,
58 maps corresponding outbound memory window so to have access to the shared
59 memory region.
66 Memory: Local NTB Port: Peer NTB Port: Peer MMIO:
68 | dma-mapped | | | MW base addr |<== memory-mapped IO
69 | memory | | |--------------|
70 | (addr) |<===================| MW xlat addr |<-ntb_peer_mw_set_trans(addr)
71 |------------| | |--------------|
74 1) allocate a memory region, 2) somehow deliver a translated address to a peer
75 device, 3) peer puts the translated address to NTB config, 4) peer device maps
76 outbound memory window so to have access to the shared memory region.
82 1) Allocate memory for a shared window
83 2) Initialize memory window by translated address of the allocated region
84 (it may fail if local memory window initialization is unsupported)
85 3) Send the translated address and memory window index to a peer device
88 1) Initialize memory window with retrieved address of the allocated
89 by another device memory region (it may fail if peer memory window
91 2) Map outbound memory window
93 In accordance with this scenario, the NTB Memory Window API can be used as
97 1) ntb_mw_count(pidx) - retrieve number of memory ranges, which can
98 be allocated for memory windows between local device and peer device
100 2) ntb_get_align(pidx, midx) - retrieve parameters restricting the
101 shared memory region alignment and size. Then memory can be properly
103 3) Allocate physically contiguous memory region in compliance with
105 4) ntb_mw_set_trans(pidx, midx) - try to set translation address of
106 the memory window with specified index for the defined peer device
108 5) Send translated base address (usually together with memory window
109 number) to the peer device using, for instance, scratchpad or message
113 1) ntb_peer_mw_set_trans(pidx, midx) - try to set received from other
114 device (related to pidx) translated address for specified memory
117 2) ntb_peer_mw_get_addr(widx) - retrieve MMIO address to map the memory
118 window so to have an access to the shared memory.
120 Also it is worth to note, that method ntb_mw_count(pidx) should return the
121 same value as ntb_peer_mw_count() on the peer with port index - pidx.
124 ------------------------------------------------------------------
127 Netdev. These drivers function together to create a logical link to the peer,
128 across the ntb, to exchange packets of network data. The Transport client
129 establishes a logical link to the peer, and creates queue pairs to exchange
136 -----------------------------------------
138 The Ping Pong test client serves as a demonstration to exercise the doorbell
140 Ping Pong enables the link when started, waits for the NTB link to come up, and
141 then proceeds to read and write the doorbell scratchpad registers of the NTB.
143 shifted by one in each round, to test the behavior of multiple doorbell bits
145 scratchpad, and writes the value plus one to the first peer scratchpad, each
150 * unsafe - Some hardware has known issues with scratchpad and doorbell
151 registers. By default, Ping Pong will not attempt to exercise such
154 * delay\_ms - Specify the delay between receiving a doorbell
157 * init\_db - Specify the doorbell bits to start new series of rounds. A new
160 * dyndbg - It is suggested to specify dyndbg=+p when loading this module, and
161 then to observe debugging output on the console.
164 --------------------------------
176 NTB device probed by the tool. This directory is shortened to *hw*
179 This file is used to read, set, and clear the local doorbell. Not
180 all operations may be supported by all hardware. To read the doorbell,
181 read the file. To set the doorbell, write `s` followed by the bits to
182 set (eg: `echo 's 0x0101' > db`). To clear the doorbell, write `c`
183 followed by the bits to clear.
185 This file is used to read, set, and clear the local doorbell mask.
188 This file is used to read, set, and clear the peer doorbell.
191 This file is used to read, set, and clear the peer doorbell
194 This file is used to read and write local scratchpads. To read
195 the values of all scratchpads, read the file. To write values, write a
198 # to set scratchpads `4` and `7` to `0x123` and `0xabc`, respectively).
200 This file is used to read and write peer scratchpads. See
204 ------------------------------------
206 The MSI test client serves to test and debug the MSI library which
207 allows for passing MSI interrupts across NTB memory windows. The
212 NTB device probed by the msi test. This directory is shortened to *hw*
237 ------------------------------------------
244 If the peer ntb is to be accessed via a memory window, then use
245 this memory window to access the peer ntb. A value of zero or positive
248 `-1`.
250 If the peer ntb is to be accessed via a memory window, and if
251 the memory window is large enough, still allow the client to use the
252 second half of the memory window for address translation to the peer.
257 * xeon\_b2b\_usd\_bar4\_addr64 - See *xeon\_b2b\_bar2\_addr64*.
258 * xeon\_b2b\_usd\_bar4\_addr32 - See *xeon\_b2b\_bar2\_addr64*.
259 * xeon\_b2b\_usd\_bar5\_addr32 - See *xeon\_b2b\_bar2\_addr64*.
260 * xeon\_b2b\_dsd\_bar2\_addr64 - See *xeon\_b2b\_bar2\_addr64*.
261 * xeon\_b2b\_dsd\_bar4\_addr64 - See *xeon\_b2b\_bar2\_addr64*.
262 * xeon\_b2b\_dsd\_bar4\_addr32 - See *xeon\_b2b\_bar2\_addr64*.
263 * xeon\_b2b\_dsd\_bar5\_addr32 - See *xeon\_b2b\_bar2\_addr64*.