NTB_HW_AMD(4) FreeBSD Kernel Interfaces Manual NTB_HW_AMD(4)
NAME
ntb_hw_amd - AMD Non-Transparent Bridge driver
SYNOPSIS
To compile this driver into your kernel, place the following lines in
your kernel configuration file:
device ntb
device ntb_hw_amd
Or, to load the driver as a module at boot, place the following line in
loader.conf(5):
ntb_hw_amd_load="YES"
The following sysctls are supported in this driver
dev.ntb_hw.X.info
Reading this sysctl will give the basic details like the number of memory
windows, scratchpads and doorbells exposed by the NTB on the local host
to access the devices beyond the bridge. It also provides details about
the masked doorbells, translation address and size limit of each exposed
memory window and link status information.
DESCRIPTION
The ntb_hw_amd driver provides support for the Non-Transparent Bridge
(NTB) hardware in AMD EPYC processor family. The Non-Transparent Bridge
does not look as a regular PCI bridge, but as PCI endpoint device, hiding
the devices behind it. The driver hides details of hardware on the other
side, but exposes memory windows, scratchpads and doorbells to access the
other side via hardware independent KPI to ntb(4) subsystem.
The hardware provides 2 (both 64-bit) or 3 (one 32-bit and two 64-bit)
memory windows to the other system's memory, up to 16 scratchpad
registers and 16 doorbells to communicate with and interrupt the other
system respectively.
CONFIGURATION
The NTB configuration should be set by BIOS. This includes enabling NTB,
choosing topology (only NTB-to-Root Port mode is supported now), role of
the host in the topology. This needs to be done on both systems.
The BAR size for memory windows is configured to 1 MiB by default.
SEE ALSO
if_ntb(4), ntb(4), ntb_transport(4)
AUTHORS
The ntb_hw_amd driver was developed by AMD and originally written by
Rajesh Kumar <
[email protected]>. Reviewed by Alexander Motin
<
[email protected]>, Conrad E. Meyer <
[email protected]> and Warner Losh
<
[email protected]>.
FreeBSD 14.1-RELEASE-p8 August 29, 2019 FreeBSD 14.1-RELEASE-p8