[SeaBIOS] Does SeaBIOS uses the BIOS interfaces itself?

Kevin O'Connor kevin at koconnor.net
Wed Mar 20 00:17:11 CET 2013

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?)

> 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).


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