[Nix-dev] mips64, loongson2f or what

[Lluís Batlle i Rossell]

Hello,

when I started porting nixpkgs into the fuloong mini pc system (a computer using
the processor loongson2f), I used r0bertz Gentoo for loongson2f (abi n32).

There, nix thought that the system was "ict_loongson-2_v0.3_fpu_v0.1-linux".

After using a properly built nix, with a stdenvLinux, I noticed that nix thought
that the system was "mips64-linux".

In order not to rebuild all, now I'm using the nix.conf option
"system = ict_loongson-2_v0.3_fpu_v0.1-linux".

So, where to go from that? I think that:
- The bootstrap-tools I have can run in any mips3, linux >= 2.6.32 with n32 abi support.
- The stdenv should know about the architecture, compiling all with
  "-march=loongson2f" (this enables some SIMD instructions and double ALU in
  gcc, but only if set explicitly in the code I think)
  Building the stdenv gcc with "--with-arch=loongson2f" should do.

But, I'm not sure whether to maintain that weird
ict_loongson-2_v0.3_fpu_v0.1-linux (indicative of loongson2f), think of a new
system string, go to "mips64-linux" although all but the bootstrap-tools would
be for loongson2, use platform.name to distinguish what mips64, ...

I think this resembles the case where someone would want an i686 nixpkgs with
sse and an i686 nixpkgs with sse2. Any advice? Or I better do whatever is
easier, and we will solve any problem on the way if it ever appears (someone
using nixos on a mips64 not loongson2f)

Regards,
Lluís.