Re: [Qemu-devel] [PATCH 2/3] target-mips:enabling of 64 bit user mode and floating point operations MIPS_HFLAG_UX is included in env->hflags so that the address computation for LD instruction does not treated as 32 bit code see gen_op_addr_add() in translate.c

[Richard Henderson]

On 12/08/2011 04:04 PM, Andreas Färber wrote:
>> > +    /* if cpu has FPU, MIPS_HFLAG_F64 must be included in env->hflags
>> > +       so that floating point operations can be emulated */
>> > +    env->active_fpu.fcr0 = env->cpu_model->CP1_fcr0;
>> >      if (env->active_fpu.fcr0 & (1 << FCR0_F64)) {
>> >          env->hflags |= MIPS_HFLAG_F64;
>> >      }
> Nack. env->active_fpu.fcr0 gets initialized in translate_init.c based on
> cpu_model->CR1_fcr0, where FCR0_F64 is set only for 24Kf, 34Kf,
> MIPS64R2-generic. TARGET_ABI_MIPSN64 linux-user defaults to 20Kc. So it
> seems to rather be an issue of using the right -cpu parameter or
> changing the default for n64. [cc'ing Nathan, who introduced the if]

That said, there's still something missing, e.g. MIPS_HFLAG_COP1X.
My first guess is simply

    if (env->insn_flags & (ISA_MIPS32 | ISA_MIPS4)) {
        env->hflags |= MIPS_HFLAG_COP1X;
    }

immediately after this MIPS64 hunk.


r~