Re: [Qemu-devel] [RFC] target/mips: Initial support for MIPS R5900

[Jürgen Urban]

Hello Fredrik,

> Gesendet: Samstag, 07. Juli 2018 um 21:41 Uhr
> Von: "Fredrik Noring" <address@hidden>
> An: address@hidden
> Cc: "Maciej W. Rozycki" <address@hidden>, "Jürgen Urban" <address@hidden>
> Betreff: [RFC] target/mips: Initial support for MIPS R5900
>
> Hi,
> 
> This patch implements initial QEMU support for the MIPS R5900. Primarily
> code generated by GCC. The only special instruction needed for this, as far
> as I can tell, is the three-operand multiply.
> 
> The MIPS R5900 is normally taken to be MIPS3, but it has MOVN, MOVZ and PREF
> defined in MIPS4 which is why ISA_MIPS4 is chosen for this patch.
> 
> I have tested the patch with Linux user mode emulation on a root filesystem
> compiled for R5900 and it worked without apparent issues, apart from:
> 
>       qemu: Unsupported syscall: 4352 (seccomp)
> 
> Some flags in the mips_defs array are marked FIXME as I don't know the
> proper values.
> 
> Would this patch be an acceptable initial submission for the MIPS R5900?

I think it is a good first step.
As the GCC doesn't generate VU instructions and there are several optimisations 
missing in the GCC, I assume it will not be able to handle a larger test like:
https://sourceforge.net/p/kernelloader/ps2linux-toolchain/ci/master/tree/minimalistic

As it will later access /dev/ps2gs, you will need to run the qemu on the PS2 to 
be able to run the test completely.
Note: As the official Linux kernel has several bugs and the test tries to 
exploit them, it may not be possible to execute the test without my PS2 Linux 
patches.

Best regards
Jürgen Urban