[SeaBIOS] Does SeaBIOS uses the BIOS interfaces itself?

[Paul Menzel]

Am Dienstag, den 19.03.2013, 19:17 -0400 schrieb Kevin O'Connor:
> On Mon, Mar 18, 2013 at 11:57:31AM +0100, Paul Menzel wrote:
> > Dear SeaBIOS folks,
> > 
> > 
> > looking at
> > 
> > $ more src/Kconfig
> > […]
> >     config AHCI
> >         depends on DRIVES
> >         bool "AHCI controllers"
> >         default y
> >         help
> >             Support for AHCI disk code.
> > […]
> > 
> > disabling the »Drive interface« (which sets(?) `DRIVES`) in the menu
> > BIOS interfaces, support for booting from an AHCI device is disabled
> > too.
> 
> The dependency is there because there is no use in compiling in a disk
> device driver if there is no external interface to access disks.
> (What value would there be in having an AHCI driver if the BIOS
> doesn't support reading from disks?)

Hearing of filo or GRUB 2 as payload, I thought these interfaces are not
needed for actual booting. But assuming is not good as Peter pointed
out.

> > So for my understanding, in the current implementation SeaBIOS uses its
> > own BIOS interfaces although strictly it would not be necessary. Is that
> > correct?
> 
> I don't understand your question.  Sometimes SeaBIOS calls external
> 16bit disk interfaces when it wishes to read from a drive - but it
> does this only for compatibility (to handle the cases where an option
> ROM could have hooked the 16bit disk interrupt and substituted its own
> code in place of the SeaBIOS code).  This is not related to the
> Kconfig dependency however (see above).

I did not think of the option ROM. Thanks for mentioning it.


Thanks,

Paul
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