NTB(4)                 FreeBSD Kernel Interfaces Manual                 NTB(4)

NAME
     ntb - Non-Transparent Bridge subsystem

SYNOPSIS
     To compile it into your kernel, place the following lines in your kernel
     configuration file:

           device ntb

     Or, to load it as a module at boot, place the following line in
     loader.conf(5):

           ntb_load="YES"

     The following tunables are settable from the loader(8):

     hw.ntb.debug_level
     Driver debug level.  The default value is 0, higher means more verbose.

     hint.ntb_hw.X.config
     Configures a set of NTB functions, separated by commas, and their
     resource allocation.  Each function can be configured as:
     "[<name>][:<mw>[:<spad>[:<db>]]]", where: name is a name of the driver to
     attach (empty means any), mw is a number of memory windows to allocate
     (empty means all available), spad is a number of scratchpad registers to
     allocate (empty means all available), db is a number of doorbells to
     allocate (empty means all available).  The default configuration is empty
     string, which means single function with all available resources,
     allowing any driver to attach.

DESCRIPTION
     Non-Transparent Bridges connect two computer systems with PCIe link(s),
     providing each of them limited access to others memory space, scratchpad
     registers and interrupts.  The ntb subsystem uses those resources
     provided in generic way by hardware drivers and splits them between
     several functions, according to specified configuration.

SEE ALSO
     if_ntb(4), ntb_hw_amd(4), ntb_hw_intel(4), ntb_hw_plx(4),
     ntb_transport(4)

AUTHORS
     The ntb subsystem was developed by Intel and originally written by Carl
     Delsey <carl@FreeBSD.org>.  Later improvements were done by Conrad E.
     Meyer <cem@FreeBSD.org> and Alexander Motin <mav@FreeBSD.org>.

FreeBSD 13.1-RELEASE-p6         August 29, 2019        FreeBSD 13.1-RELEASE-p6