Re: Kernel for P-II on P-I.

From: Rogier Wolff (R.E.Wolff@BitWizard.nl)
Date: Fri Jul 07 2000 - 01:53:33 EST


Keith Owens wrote:
> On Thu, 6 Jul 2000 10:34:47 +0200 (MEST),
> R.E.Wolff@BitWizard.nl (Rogier Wolff) wrote:
> >A kernel compiled for P-II (or something like that) crashes without
> >saying a thing on P-I. would it be an idea to print a message?
> >("This kernel is incompatible with this processor")
>
> AFAIK that is caused by gcc using instructions that exist on P-II but
> not P-I, including instructions like conditional move (CMOVE).
> Unfortunately those instructions are used everywhere, including in
> printk. No way to get a message out without detecting the problem in
> the real mode boot loader and using BIOS I/O.

Knowing this I'd suggest that the few files that are needed to get the
message out are compiled using the standard Pentium-instructions.

The CPU generates an unimplemented instruction trap, right? Would it
be doable to write a quick and dirty handler for that trap? (That's
the method I used to get Xinu up and running on the LSI03).

                                Roger.

-- 
** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2137555 **
*-- BitWizard writes Linux device drivers for any device you may have! --*
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