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PCHB(4)		       FreeBSD Kernel Interfaces Manual		       PCHB(4)

NAME
     pchb -- PCI-Host Bridge

SYNOPSIS
     pchb* at pci?
     pci* at pchb?

DESCRIPTION
     The pchb driver provides support for PCI-Host adapter-specific functions.
     Support is	provided for the following devices:

	   i450	PCIset (Orion)
		   Supports additional PCI buses.

	   Reliance Computer ROSB4, CNB20HE, CNB20LE
		   Supports additional PCI buses.

	   i82424ZX (Saturn)
		   Disables CPU-PCI write posting.

	   i82443BX
		   Provides workaround for the following errata: "An incorrect
		   address may be driven on the	DRAM bus, resulting in memory
		   data	being fetched from the wrong location."

	   i82810/810E,	i82815/815E, i82820, i82840
		   Supports the	random numbers generator, supplying random
		   bytes from the system's thermal noise.  Driven by periodic
		   checks for available	data from the generator, it supplies
		   entropy to the random(4) driver for common usage.

     On	amd64 and i386 systems,	most PCI devices of class Bridge and sub-class
     Bridge Host are supported just as PCI attachment points.  A few other
     system control devices not	listed here are	supported by pchb.

     The macppc	port supports several Apple and	Motorola bridges.

SEE ALSO
     intro(4), pci(4), random(4)

HISTORY
     Random number generator support first appeared in OpenBSD 2.7.

AUTHORS
     Support for true RNG present on i82810 chips was added by Michael
     Shalayeff <mickey@openbsd.org>.

BUGS
     Real RNG probe should fix the PCI scanning	loop so	it would find the
     Firmware Hub (i82802) which actually contains the RNG device and probe it
     as	a real PCI device (i.e., common	PCI registers are there).

FreeBSD	13.0			 July 16, 2013			  FreeBSD 13.0

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | AUTHORS | BUGS

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