> Please separate two things.
> CPx is optional on MIPS architecture, but current kernel(without SOFTFLOAT,
> NOFPU) depends on CP1 existence right now. Lacking some CP1 instructions may
> be OK, but CP1 registers are mandatory.

Please keep in mind I've never criticized extentending missing CP1
insn emulation.

Adding certain missing CP1 insns by emulation are not tied with
#define NOFPU nor #define SOFTFLOAT, as you mentioned.  Both was a
product by lack of understanding.

> Anyway, current fp.S is very ugly, It needs completely rewritten.

The reality was none wanted to touch it since I saw 4BSD-late.

Tohru Nishimura