1.\" $OpenBSD: pchb.4,v 1.17 2007/05/31 19:19:51 jmc Exp $ 2.\" 3.\" Michael Shalayeff, 2000. Public Domain. 4.\" 5.Dd $Mdocdate: May 31 2007 $ 6.Dt PCHB 4 7.Os 8.Sh NAME 9.Nm pchb 10.Nd PCI-Host Bridge 11.Sh SYNOPSIS 12.Cd "pchb* at pci?" 13.Cd "pci* at pchb?" 14.Sh DESCRIPTION 15The 16.Nm 17driver provides support for PCI-Host adapter-specific functions. 18Support is provided for the following devices: 19.Bl -tag -width Ds -offset indent 20.It i450 PCIset (Orion) 21Supports additional PCI buses. 22.It Reliance Computer ROSB4, CNB20HE, CNB20LE 23Supports additional PCI buses. 24.It i82424ZX (Saturn) 25Disables CPU-PCI write posting. 26.It i82443BX 27Provides workaround for the following errata: 28"An incorrect address may be driven on the 29DRAM bus, resulting in memory data being 30fetched from the wrong location." 31.It i82810/810E, i82815/815E, i82820, i82840 32Supports the random numbers generator, 33supplying random bytes from the system's thermal noise. 34Driven by periodic checks for available data from the generator, 35it supplies entropy to the 36.Xr random 4 37driver for common usage. 38.El 39.Pp 40On amd64 and i386 systems, most PCI devices of class 41.Nm Bridge 42and sub-class 43.Nm Bridge Host 44are supported just as PCI attachment points. 45A few other system control devices not listed here are supported by 46.Nm . 47.Pp 48The macppc port supports several Apple and Motorola bridges. 49.Sh SEE ALSO 50.Xr intro 4 , 51.Xr pci 4 , 52.Xr random 4 53.Sh HISTORY 54Random number generator support first appeared in 55.Ox 2.7 . 56.Sh AUTHORS 57Support for true RNG present on i82810 chips was added by 58.An Michael Shalayeff Aq mickey@openbsd.org . 59.Sh BUGS 60Real RNG probe should fix the PCI scanning loop so it would find the Firmware 61Hub (i82802) which actually contains the RNG device and 62probe it as a real PCI device (i.e., common PCI registers are there). 63