MirOS Manual: bios(4)

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


     bios - a driver for PC Firmware, aka BIOS


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


     OpenBSD provides support for PC firmware, aka BIOS and some of its func-
     tions, currently: APM subsystem, BIOS 32 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  BIOS 32 attachment.

             Do not probe and attach to BIOS 32 extensions, which is one of
             the interfaces to the PCI BIOS configuration tables.

     0x0002  PCI BIOS attachment.

             Do not probe and attach the pcibios(4) device, which performs
             certain PCI configuration tasks.

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


     apm(4), intro(4), pcibios(4), pcmcia(4), powernowhack(4)


     The bios driver appeared in OpenBSD 2.2.


     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.

MirOS BSD #10-current         February 28, 2001                              1

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