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

Sebastian Herbszt herbszt at gmx.de
Sun May 8 21:27:37 CEST 2011

Kevin O'Connor wrote:
> On Sun, May 08, 2011 at 07:50:12PM +0200, Sebastian Herbszt wrote:
>> Kevin O'Connor wrote:
>> >On Thu, May 05, 2011 at 12:53:36AM +0200, Sebastian Herbszt wrote:
>> >>Got a pointer in the BBS spec?
>> >Section 5.2.3:
>> 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.
> SeaBIOS shows the boot in "6.3 Check IPL Priority and BCV Priority"
> which is between "6.2 PnP Option ROM Initialization" and "6.4 INT 13h
> Device Controller Installation".

So this is different between SeaBIOS and Bochs BIOS, which tries to display
the IPL menu.

> We want the boot menu to be able to configure which drive becomes the
> C: drive, so the boot menu must be displayed prior to running the BCVs
> and Legacy Option ROMs.

So this is more a BCV than IPL menu. Maybe the F12 message should be

>>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.
> All BCVs and legacy option roms are always called.  The only thing the
> boot menu does is determine the order of their invocation.  (See
> boot.c:boot_prep().)  If you have a counter-example then it is a bug
> and must be fixed.

This is not intuitive because other BIOSes display a boot menu after
all BCV and legacy roms were called.


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