Use of BIOS calls in modern code (Was: Re: [OpenBIOS] Why protected mode?)

[Niklas Ekström]

On Fri, 16 Jul 1999, Timothy J. Massey wrote:
> 
> Linux can't really take advantage of *any* BIOS routines (OK, outside of the
> loader and such), even when Win98 can.  The reason is simple:  Linux is
> cross-platform.  Alphas don't have the same BIOS as PC's, which don't have
> the same BIOS as Macs which don't have the same BIOS as a Sun.  So how could
> Linux use a BIOS routine that isn't commonly available.

Ofcourse Linux have architecture specific code also.

> In any kind of portable OS, any feature that isn't available on all systems
> is a liability.  It's something that will either increase the difficulty of
> porting the code to a system that doesn't support some feature, or requires
> additional effort to add that functionality to a particular port.

>From what I've heard about OS design, the trend seems to be that when
implementing the OS you are not supposed to aim for crossportability, but
for the highest possible performance on the individual platforms. What
_should_ be portable is the programming interfaces that should be common
on all supported platforms.

> Basically, the BIOS in a modern computer is a hardware configurator and boot
> loader.

I don't know what computer systems you have in mind, but at the ones I'm
thinking of (Sun, Apple etc) the BIOS is much more than that (see
OpenFirmware which is basically a Hardware Abstraction Layer).

> Personally, I think that that's fine.  I'm not looking for a BIOS
> to do anything more.

I could live with that too, but it seems very unnecessary. Consider this:

When you make the BIOS you (probably) wish to make it able to boot from
as many devices as possible (Floppy, Harddisk, CD, Network, USB...), so
then you have to include software for supporting these devices
(devicedrivers) into the BIOS.

And since you already got the drivers in the BIOS, many would feel that it
would be a complete waste not to make these available to the OS through a
BIOS Runtime Interface (BRI).

Besides, there are many major advantages of having the drivers available
through a BRI. For instance the OS doesn't have to support a million 
different chipsets (Intel, AMD, etc) and motherboards. A very small and
flexible OS could be made. Also, the OS developers could concentrate on
making cool OS features instead of writing drivers to support hardware.

/ Niklas

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