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