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

Sebastian Herbszt herbszt at gmx.de
Sun May 8 19:50:12 CEST 2011

Kevin O'Connor wrote:
> 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.

Chapter 6 describes the POST sequence:
- Initializing BAIDs, PnP Boot Devices
- PnP Option ROM Initialization
- INT 13h Device Controller Installation (BCV, Legacy ROM Scan, On-board ATA Support)
- IPL processing

So by the time the boot menu is displayed all BCVs and legacy roms should have already been called.
This doesn't seem to be currently true for legacy roms. PnP roms are called but legacy roms are not. They
are only called if they are selected from the boot menu.


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