Re: [Qemu-devel] [PATCH v2 4/6] target/mips: Fix decoding mechanism of special R5900 opcodes

[Maciej W. Rozycki]

On Fri, 9 Nov 2018, Aleksandar Markovic wrote:

> > ... and DMULT, DMULTU, DDIV and DDIVU
> > are part of the MIPS III ISA. They are emulated in user mode to support
> > generic MIPS III programs.
> 
> Pure MIPS III executables should not be a concern of the R5900 
> emulation, but R5900 executables.

 I repeat: MIPS III is the available instruction set defined with the base 
64-bit MIPS Linux psABI and must not be subsetted.  You have to support it 
in QEMU Linux user emulation mode for any 64-bit MIPS processor and this 
is not debatable, period.  QEMU has no control over the Linux ABI, it has 
to accept it as it is.

  Maciej