Re: [Qemu-devel] [PATCH 06/11] target-arm: Add comment about not implementing NSACR.RFR

[Sergey Fedorov]

On 15.02.2016 20:22, Peter Maydell wrote:
> QEMU doesn't implement the NSACR.RFR bit, which is a permitted
> IMPDEF in choice in ARMv7 and the only permitted choice in ARMv8.
> Add a comment to bad_mode_switch() to note that this is why
> FIQ is always a valid mode regardless of the CPU's Secure state.
>
> Signed-off-by: Peter Maydell <address@hidden>

Reviewed-by: Sergey Fedorov <address@hidden>

> ---
>  target-arm/helper.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/target-arm/helper.c b/target-arm/helper.c
> index 9998a25..37b5439 100644
> --- a/target-arm/helper.c
> +++ b/target-arm/helper.c
> @@ -5180,6 +5180,9 @@ static int bad_mode_switch(CPUARMState *env, int mode)
>      case ARM_CPU_MODE_UND:
>      case ARM_CPU_MODE_IRQ:
>      case ARM_CPU_MODE_FIQ:
> +        /* Note that we don't implement the IMPDEF NSACR.RFR which in v7
> +         * allows FIQ mode to be Secure-only. (In v8 this doesn't exist.)
> +         */
>          return 0;
>      case ARM_CPU_MODE_MON:
>          return !arm_is_secure(env);