BIOS(4)               OpenBSD Programmer's Manual (i386)               BIOS(4)

NAME
     bios - a driver for PC Firmware, aka BIOS

SYNOPSIS
     bios0    at mainbus0 flags 0x0000
     apm0     at bios0 flags 0x0000
     pcibios0 at bios0 flags 0x0000

DESCRIPTION
     OpenBSD provides support for PC firmware, aka BIOS and some of its func-
     tions, currently: APM subsystem, BIOS32 extensions, PCI BIOS subsystem.

     The bios driver also identifies BIOS type (such as "AT/286+", which is
     almost always used in modern machines) and BIOS image date stamp, which
     is, presumably, the day the BIOS image was compiled by vendor and could
     be used as a crude BIOS version identification.  The bios driver also
     scans the ISA memory hole at 640K-1M for optional ROM images and reserves
     the space from being used by various ISA devices, for example pcic(4).

     Flags is a bit mask, each bit of which specifies which functions of the
     driver to disable.

     0x0001  BIOS32 attachment.

             Do not probe or attach to BIOS32 extensions.  BIOS32 is one of
             the interfaces to the PCI BIOS configuration tables.

     0x0002  PCI BIOS attachment.

             Do not probe or attach the pcibios(4) device, which performs cer-
             tain PCI configuration tasks.

     0x0004  Do not perform the scan for ROM images in the ISA memory hole
             (0xc0000 - 0xf0000 physical addresses).

     0x0008  SMBIOS attachment.

             Do not probe or attach to SMBIOS.  SMBIOS provides greater detail
             about system hardware configuration and is required to attach
             ipmi(4) on most systems.

SEE ALSO
     apm(4), intro(4), pcibios(4), pcmcia(4)

HISTORY
     The bios driver appeared in OpenBSD 2.2.

BUGS
     On some machines optional ROM images do not pass checksum check, but it's
     considered better to reserve space for those anyway, choosing lesser evil
     from many.

OpenBSD 4.7                      May 31, 2007                                1
