[SeaBIOS] Non-PNP legacy option rom scan and init

Kevin O'Connor kevin at koconnor.net
Thu May 5 02:11:07 CEST 2011

On Thu, May 05, 2011 at 12:53:36AM +0200, Sebastian Herbszt wrote:
> Kevin O'Connor wrote:
> >On Tue, May 03, 2011 at 11:38:45PM +0200, Sebastian Herbszt wrote:
> >>SeaBIOS doesn't seem to call non-PNP legacy option roms and handles
> >>them like BCV.  I think this behaviour is incorrect because non-PNP
> >>legacy option roms should get called without exceptions.
> >
> >SeaBIOS calls all non-PNP option roms unconditionally.  It places them
> >in the "BootList" so that it can order their invocation relative to
> >PNP option roms.  This is the recommendation of the BBS spec - the
> >idea is that many legacy option roms hook the C: drive - so ordering
> >their invocation allows a PNP drive to hook the C: drive first.
> Got a pointer in the BBS spec?

Section 5.2.3:

5.2.3 Legacy Cards with Option ROMs

The third type of entry in the BCV Table is all Legacy cards with
option ROMs. A Legacy card will install its INT 13h drive support when
the BIOS calls the Legacy card's initialization vector. No attempt is
made to enumerate or control the installation order of individual
devices, although nothing defined in this specification prevents this.

Sections 5.3 and 5.4 go into further detail.


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