ASM/C and 16/32 bit questions.

[David Woodhouse]

We're going to have to provide a standard 16-bit BIOS interface if we want to 
support DOS and Windows users. There's not a lot of chance of making the BIOS 
go straight into 32-bit mode and stay there.

We can still use C in 16-bit mode - take a look at the elks development utils, 
which are quite suitable for this task.

I think we want to write most of it in C, with some critical sections in ASM - 
after http://dwmw2.robinson.cam.ac.uk/devload/ I really don't want to think 
about large projects written solely in assembly.

----                              ----                              ----
David Woodhouse, Robinson College, CB3 9AN, England.   ([phone]
    [e-mail]        http://dwmw2.robinson.cam.ac.uk
        finger [e-mail] for PGP key.

---
OpenBIOS -- http://www.linkscape.net/openbios/
[e-mail]   Body: un/subscribe
Problems?  [e-mail]

[Adam Wiggins]

On Tue, 17 Feb 1998, David Woodhouse wrote:
> We're going to have to provide a standard 16-bit BIOS interface if we want to 
> support DOS and Windows users. There's not a lot of chance of making the BIOS 
> go straight into 32-bit mode and stay there.

This might be a really bad idea but let me know what you think
anyway :) How about doing a really low level boot loader of some sort so
if your booting linux it goes into 32bit protected mode early where as if
you boot dos or win it loads into 16-bit mode with all the int's that are
needed?
> I think we want to write most of it in C, with some critical sections in ASM - 
> after http://dwmw2.robinson.cam.ac.uk/devload/ I really don't want to think 
> about large projects written solely in assembly.

:)

---
OpenBIOS -- http://www.linkscape.net/openbios/
[e-mail]   Body: un/subscribe
Problems?  [e-mail]

[Dave Cinege]

Adam Wiggins wrote:
> On Tue, 17 Feb 1998, David Woodhouse wrote:
> > We're going to have to provide a standard 16-bit BIOS interface if we want to
> > support DOS and Windows users. There's not a lot of chance of making the BIOS
> > go straight into 32-bit mode and stay there.
>     This might be a really bad idea but let me know what you think
>
> anyway :) How about doing a really low level boot loader of some sort so
> if your booting linux it goes into 32bit protected mode early where as if
> you boot dos or win it loads into 16-bit mode with all the int's that are
> needed?

Boot entry with DOS compatibility option??

---
OpenBIOS -- http://www.linkscape.net/openbios/
[e-mail]   Body: un/subscribe
Problems?  [e-mail]

On Wed, 18 Feb 1998, Adam Wiggins wrote:
> On Tue, 17 Feb 1998, David Woodhouse wrote:
> > We're going to have to provide a standard 16-bit BIOS interface if we want to 
> > support DOS and Windows users. There's not a lot of chance of making the BIOS 
> > go straight into 32-bit mode and stay there.
>
> This might be a really bad idea but let me know what you think
> anyway :) How about doing a really low level boot loader of some sort so
> if your booting linux it goes into 32bit protected mode early where as if
> you boot dos or win it loads into 16-bit mode with all the int's that are
> needed?

what is so wrong with it just booting 16bit mode? we KNOW we can't force
standards like 32bit BIOS upon the already overwhelming MS crowd
> > I think we want to write most of it in C, with some critical sections in ASM - 
> > after http://dwmw2.robinson.cam.ac.uk/devload/ I really don't want to think 
> > about large projects written solely in assembly.
>
> :)
>
> OpenBIOS -- http://www.linkscape.net/openbios/
> [e-mail]   Body: un/subscribe
> Problems?  [e-mail]

_        _  __     __             _ _                                  _
|        / |/ /_ __/ /_____         |       Nuke Skyjumper               |
|       /    / // /  '_/ -_)        |         "Master of the Farce"      |
|_     /_/|_/_,_/_/_\__/        _|_           [e-mail]       _|

---
OpenBIOS -- http://www.linkscape.net/openbios/
[e-mail]   Body: un/subscribe
Problems?  [e-mail]

[Chris Arguin]

On Wed, 18 Feb 1998 [e-mail] wrote:
> On Wed, 18 Feb 1998, Adam Wiggins wrote:
> > This might be a really bad idea but let me know what you think
> > anyway :) How about doing a really low level boot loader of some sort so
> > if your booting linux it goes into 32bit protected mode early where as if
> > you boot dos or win it loads into 16-bit mode with all the int's that are
> > needed?
>
> what is so wrong with it just booting 16bit mode? we KNOW we can't force
> standards like 32bit BIOS upon the already overwhelming MS crowd

Well, some of us want to use our BIOS for better things :)

Some people (mostly Linux users, but eventually HURD, BEos, and whatever
Sun is whipping up) can go without all the old stuff still supported. If
it is a compile-time option to support them, then we can use the spare
room in the BIOS for something like the Alpha's SRM console.

I guess I would envision 'DOS Support' as a device to be included :)
Most people, myself included, would include it. But if we are gonna let
them compile the BIOS, we might as well give them the choice.

Yes, I realize that the Linux kernel would have to be slightly rewritten
to use the new BIOS, but why not?

---
OpenBIOS -- http://www.linkscape.net/openbios/
[e-mail]   Body: un/subscribe
Problems?  [e-mail]