Re: X11 and mc68060...

[Ignatios Souvatzis <ignatios%theory.cs.uni-bonn.de@localhost>]

Ruben van Staveren did not believe Markus Illenseer:
> > 
> > > Really? Why exactly?
> > 
> >  Same way as -040 binaries wont work on -000: Different instruction set.
> 
> 
> Well, you name something completely different here, like missing instructions
> to my knowledge, the -m68060 does instruct our patched gcc not to use
> machine instructions that would make the mc68060 go in supervisor mode
> to emulate them in software. Even the generic kernel is compiled with
> -m68060 right ? so this kernel could not even boot on 680[234]0.

> The only slight disadvantage is loss of performance on pre 060 cpu's due
> to using the (faster-in-their-point) 060 friendly instructions.


Your understanding of -m68060 is incomplete.

-m68060, as currently implemented, is like -m68040, with the additional 
 omission of 68060 unfriendly integer instructions.

Both -m68040 and -m68060 create FP instructions that are NOT implemented on
the 68881 and 68882 coprocessors.

This is no problem for the kernel (which does not do any FP computations of
its own), but WILL break many user programs.

Regards,
        Ignatios Souvatzis

(who once made the mistake to compile his X server with -m68060, and needed
a while ot understand why it crashed on the 68030 machine, on which he 
occasionally boots NetBSD.)