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33 .Nd PLX/Avago/Broadcom Non-Transparent Bridge driver
35 To compile this driver into your kernel,
36 place the following lines in your kernel configuration file:
37 .Bd -ragged -offset indent
39 .Cd "device ntb_hw_plx"
42 Or, to load the driver as a module at boot, place the following line in
44 .Bd -literal -offset indent
48 The following tunables are settable from the
51 .It Va hint.ntb_hw. Ns Ar X Ns Va .b2b
52 Being set to 1 (default) tells the driver attached to Virtual Interface of the
53 NTB that it works in NTB-to-NTB (back-to-back) mode, 0 -- NTB-to-Root Port.
54 Driver attached to Link Interface (visible from Root Port side) switches to
55 NTB-to-Root Port mode automatically, but one attached to Virtual Interface
56 can't detect what is on the other side and require external knowledge.
57 .It Va hint.ntb_hw. Ns Ar X Ns Va .split
58 Being set above zero splits BAR2 into 2^x memory windows using Address
64 driver provides support for the Non-Transparent Bridge (NTB) hardware in
65 PLX PCIe bridge chips, which allow up to two of their PCIe ports to be
66 switched from transparent to non-transparent bridge mode.
67 In this mode bridge looks not as a PCI bridge, but as PCI endpoint device.
68 The driver hides hardware details, exposing memory windows, scratchpads
69 and doorbells of the other side via hardware independent KPI to
73 Each PLX NTB provides up to 2 64-bit or 4 32-bit memory windows to the
74 other system's memory, 6 or 12 scratchpad registers and 16 doorbells to
75 interrupt the other system.
76 If Address Lookup Table (A-LUT) is enabled, BAR2 can be split into several
77 (up to 128) memory windows.
78 In NTB-to-NTB mode one of memory windows (or half of it, if bigger then 1MB)
79 is consumed by the driver itself to access scratchpad and doorbell registers
82 The following PLX/Avago/Broadcom chips are supported by the
99 , but it may also work with other compatible ones.
101 The basic chip configuration should be done by serial EEPROM or via i2c.
102 It includes enabling NTB on one or both sides (choosing between NTB-to-NTB
103 (back-to-back) and NTB-to-Root Port modes) and configuring BARs sizes.
105 The recommended mode is NTB-to-NTB mode, since while NTB-to-Root Port is
106 generally supported by the driver, it require PCI hotplug handling on the
107 Root Port, that may be difficult or cause different kinds of problems.
110 .Xr ntb_transport 4 ,
116 driver was written by
117 .An Alexander Motin Aq Mt mav@FreeBSD.org .
119 There is no way to protect your system from malicious behavior on the other
120 system once the link is brought up.
121 Anyone with root or kernel access on the other system can read or write to
122 any location on your system.
123 In other words, only connect two systems that completely trust each other.