Re: Question about GCC

[Ignatios Souvatzis <is%jocelyn.rhein.de@localhost>]

On Wed, Oct 21, 1998 at 05:55:47PM -0500, Bo Najdrovsky wrote:
> % If you insist to use -m68040, you still would need the additional
> % -Wa,-m68030 to make gas understand the inline assembler in (e.g.)
> 
> This is indeed what I did, and my new 040 optimized kernel is buzzing 
> along just fine.  I figured that it should be safe to use the -Wa option
> since you did it for the 060 support.  ;-)
> 
> % machdep.c, amiga_start.c for cache manipulation, _which is incompatible
> % between cpus!_ and thus handled by 68020/30 assembler opcodes and .word
> % instructions for th 68040 and 68060. Read the code if you want to
> % understand the details.
> 
> I'll check it out.  One thing that I find interesting is that supplying
> the assembler with the -m68030 flag doesn't cause it to choke if the compiler
> feeds it 040 specific instructions.

There aren't any.

That is, all 040/060 _specific_ instructions which exist, are
- Floating point ... we dont use them in the kernel (other than fsave, frestore
and fmovem, which arent 040/60 specific) Basically just
F{S,D}{ADD,SUB,MUL,DIV,MOVE,maybe a few more}

- supervisor instructions: the compiler doenst create any. All we need in the
kernel  are either generic or created by .word xxx pseudo ops, and created
either by using inline assembler or by the locore.s file.

Regards,
        -is