[OpenBIOS] openbios and via

[Clive Jenkins]

At 00:44 16/09/99 -0400, Jeff Garzik wrote:
>Is this list still alive?  I don't see any links to mail archives, but
>the files in the latest source archive are about 10 months old.
>
Well, I'm listening!


>...
>Can motherboard chipset coding be done in C?  If not, what needs to be
>fixed before this can happen?
>
Yes. Chipset registers are normally accessed via I/O ports. Most C
compilers provide appropriate functions such as:

unsigned char	inportb  (unsigned short _port);
unsigned short	inportw  (unsigned short _port);
void		outportb (unsigned short _port, unsigned char  _data);
void		outportw (unsigned short _port, unsigned short _data);

and/or

unsigned char	inp(unsigned short _port);
unsigned short	inpw(unsigned short _port);
void		outp(unsigned short _port, unsigned char _data);
void		outpw(unsigned short _port, unsigned short _data);

The actual types vary between C implementations. Output functions may not
be void: they may return the same _data.


>Also, is www.openbios.org DNS down?  I can't seem to complete a lookup,
>much less a web hit.
>
I can't access it site either. I believe information about this can be
found at <http://www.freiburg.linux.de/openbios/>.
--------

At 14:44:11 16/09/99 -0400, Jeff Garzik wrote:
>Finally, another question:  Does OpenBIOS ('make config ; make') built a
>32-bit protected mode image, or a 16-bit image?  The make output seems
>to imply both, though most of the code I look at is 16-bit.
>
>Can we do _everything_ in protected mode?
>
BIOS normally operates in real mode, except for identifying the processor
and certain POST tests done in protected mode. All calls from the operating
system or application program into the BIOS (via software interrupts) will
be done in real mode. All calls out of the BIOS (e.g.: to external BIOS
ROMs detected during the ROM scan; to the boot code on the boot sector of
the disk containing the operating system) must also be in real mode. Apart
from these requirements, there is no reason in principle why internal
portions of BIOS code should not run in protected mode. However in practice
I think you would find it very inconvenient having to switch modes all the
time.
--------

At 18:37:48 16/09/99 -0400, Jeff Garzik wrote:
>... What needs to be done, to write chipset
>drivers in C?
>
For a start you will need a fully detailed data sheet on the chipset, and
any applications notes and code examples you can find on the chipset's
manufacturer's web site.
--------

Clive

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