Re: [PATCH v2] MIPS: Add basic R5900 support

[Fredrik Noring <noring@nocrew.org>]

Hi Maciej,

>  In any case you'll have to find a MIPS I or MIPS II distribution, like an 
> older version of Debian.

I will see what I can find. I currently have Black Rhino based on Debian
and tailored for the R5900, as you verified.

>  The three-argument MUL is a part of the base MIPS32 architecture BTW, 
> originating from the IDT R4650 and the NEC Vr5500 processors.  It has 
> nothing to do with the DSP ASE (though it may have been claimed originally 
> to be a DSP enhancement).

Ah, I was referring to a press release that appears to be written by
MIPS Technologies (linked from Wikipedia):

    In addition, DSP enhancements such as multiply (MUL) and multiply and
    add (MADD) instructions have been standardized and added to the new
    architectures. While these instructions have been available as
    licensee-specific extensions in the past, this is the first time that
    they have been available as a standard part of the MIPS(R) architecture.

https://www.thefreelibrary.com/MIPS+Technologies,+Inc.+Enhances+Architecture+to+Support+Growing+Need...-a054531136

> > For this reason the R5900 patch modifies the __{save,restore}_dsp macros,
> > mips_dsp_state::dspcontrol, DSP_INIT, sigcontext32::sc_dsp, etc. I've seen
> > the cpu_has_dsp macro too, but haven't looked at the details of this yet.
> 
>  Given that the R5900 does not expand DSP support anyhow that sounds 
> suspicious to me.

Yes, I agree.

Fredrik