Re: [Qemu-devel] [PATCH v5 2/5] target/arm: handle M-profile semihosting at translate time

["Alex Bennée" <alex.bennee@linaro.org>]

Peter Maydell <peter.maydell@linaro.org> writes:

> On Wed, 11 Sep 2019 at 17:50, Alex Bennée <alex.bennee@linaro.org> wrote:
>>
>> We do this for other semihosting calls so we might as well do it for
>> M-profile as well.
>>
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>>
>> ---
>> v2
>>   - update for change to gen_exception_internal_insn API
>> v3
>>   - update for decode tree
>> v4
>>   - use !IS_USER
>> ---
>
>> diff --git a/target/arm/translate.c b/target/arm/translate.c
>> index 34bb280e3da..6689acc911e 100644
>> --- a/target/arm/translate.c
>> +++ b/target/arm/translate.c
>> @@ -8424,7 +8424,13 @@ static bool trans_BKPT(DisasContext *s, arg_BKPT *a)
>>      if (!ENABLE_ARCH_5) {
>>          return false;
>>      }
>> -    gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
>> +    if (arm_dc_feature(s, ARM_FEATURE_M) &&
>> +        semihosting_enabled() && !IS_USER(s) &&
>> +        (a->imm == 0xab)) {
>> +        gen_exception_internal_insn(s, s->base.pc_next, EXCP_SEMIHOST);
>> +    } else {
>> +        gen_exception_bkpt_insn(s, syn_aa32_bkpt(a->imm, false));
>> +    }
>>      return true;
>>  }
>
> This is still disabling semihosting for the linux-user-mode
> build for M-profile, isn't it ?

Sure - as rth suggested. But m-profile doesn't run Linux so why would we
support it in linux-user?

>
> thanks
> -- PMM


--
Alex Bennée