Re: RFC & patch: Rework MIPS command-line handling

[Thiemo Seufer <ica2_ts at csv dot ica dot uni-stuttgart dot de>]

Maciej W. Rozycki wrote:
> On Mon, 15 Jul 2002, Thiemo Seufer wrote:
> 
> > Note that the MIPS II is a deviation from stock o32 ABI, the
> > linux-mips kernel emulates the necessary instructions on MIPS I
> > hardware. This means we have an o32-linux ABI there.
> 
>  Does it?  I haven't seen any code to emulate trap, branch likely, dword
> coprocessor transfer instructions.  What is emulated are only the ll and
> sc instructions, but they are only a small subset of MIPS II extensions
> which is never used by gcc, unlike the others.

You are right, only ll/sc are emulated.

> > > If they're using mipsisa64sb1-linux, they probably expect built-in
> > > support for, say, MIPS-3D, MDMX .ob, and the few SB-1 extensions as
> > > well, regardless of the ABI they choose on the command line.
> > 
> > If all of the hardware for this target supports these, ok.
> > But the ISA pre-selection should then be done in the target specific
> > code and not globally.
> 
>  If a target triplet defines a CPU, it should always be used as the
> default for uniformity.

I agree.


Thiemo