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Re: 68030 code when building for 68060?



On Mon, Feb 07, 2005 at 11:13:21AM +0100, Gunther Nikl wrote:
> On Sat, Feb 05, 2005 at 09:26:25PM +0100, Hubert Feyrer wrote:
> > 
> > I stumbled across the following line in 
> > src/sys/arch/amiga/conf/Makefile.amiga:
> > 
> >     .if empty(IDENT:M-DM68060)
> >     CMACHFLAGS=     -m68020
> >     .else
> > ===>        CMACHFLAGS=     -m68060 -Wa,-m68030 -Wa,-m68851
> >     .endif
> > 
> > My question is, why bother with producing code for the 68030 when it's 
> > known that the target is a 68060?
> 
>   Assembler switches are different to compiler switches. With -Wa you
>   tell the assembler that it shall recognize certain instructions. Those
>   -Wa are nothing to worry about.

To be precise: as the assembler can't be told to recognize all CP/MMU
variants' MMU and cache syntaxes at once, and for some CPU/MMUs, the same
mnemonic translates to different instruction codes, we have to chose one
cpu/mmu with which we use symbolic instructions, and we're using .word
pseudo-instructions for all the others.

Regards,
        -is
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