Re: [Qemu-devel] [PATCH 04/13] linux-user/alpha: Set r20 secondary return value

[Laurent Vivier]

Le 19/05/2019 à 22:19, Richard Henderson a écrit :
> This value is not, as far as I know, used by any linux software,
> but it is set by the kernel and is part of the ABI.
> 
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  linux-user/alpha/target_cpu.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/linux-user/alpha/target_cpu.h b/linux-user/alpha/target_cpu.h
> index 140a459f73..caadb54372 100644
> --- a/linux-user/alpha/target_cpu.h
> +++ b/linux-user/alpha/target_cpu.h
> @@ -26,10 +26,12 @@ static inline void cpu_clone_regs_child(CPUAlphaState 
> *env, target_ulong newsp)
>      }
>      env->ir[IR_V0] = 0;
>      env->ir[IR_A3] = 0;
> +    env->ir[IR_A4] = 1;  /* OSF/1 secondary return: child */
>  }
>  
>  static inline void cpu_clone_regs_parent(CPUAlphaState *env)
>  {
> +    env->ir[IR_A4] = 0;  /* OSF/1 secondary return: parent */

In the kernel, r20 is only set to 0 if !(clone_flags & CLONE_SETTLS), is
this a problem here to set it unconditionally?

Thanks,
Laurent