Re: [PATCH 6/7] target/nios2: Special case ipending in rdctl and wrctl

[Peter Maydell <peter.maydell@linaro.org>]

On Sun, 27 Feb 2022 at 18:25, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> It was never correct to be able to write to ipending.
> Until the rest of the irq code is tidied, the read of ipending
> will generate an "unnecessary" mask.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/nios2/translate.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/target/nios2/translate.c b/target/nios2/translate.c
> index 52965ba17e..b17ce25a36 100644
> --- a/target/nios2/translate.c
> +++ b/target/nios2/translate.c
> @@ -452,6 +452,15 @@ static void rdctl(DisasContext *dc, uint32_t code, uint32_t flags)
>      }
>
>      switch (instr.imm5 + CR_BASE) {
> +    case CR_IPENDING:
> +        /*
> +         * The value of the ipending register is synthetic.
> +         * In hw, this is the AND of a set of hardware irq lines
> +         * with the ienable register.  In qemu, we re-use the space
> +         * of CR_IPENDING to store the set of irq lines.

maybe add
"and so we must perform the AND here, and anywhere else we need
the guest value of CR_IPENDING" ?

> +         */
> +        tcg_gen_and_tl(cpu_R[instr.c], cpu_R[CR_IPENDING], cpu_R[CR_IENABLE]);
> +        break;

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM