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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 regis-
     ters 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 <rajesh1.kumar@amd.com>.  Reviewed by	Alexander Motin
     <mav@FreeBSD.org>,	Conrad E. Meyer	<cem@FreeBSD.org> and Warner Losh
     <imp@FreeBSD.org>.

FreeBSD	13.0			August 29, 2019			  FreeBSD 13.0

NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION | SEE ALSO | AUTHORS

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