Re: [PATCH v2 05/10] accel/tcg: Handle -singlestep in curr_cflags

[Richard Henderson <richard.henderson@linaro.org>]

On 7/17/21 10:42 AM, Alex Bennée wrote:
> 
> Richard Henderson <richard.henderson@linaro.org> writes:
> 
>> Exchange the test in translator_use_goto_tb for CF_NO_GOTO_TB,
>> and the test in tb_gen_code for setting CF_COUNT_MASK to 1.
>>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   accel/tcg/cpu-exec.c      | 8 +++++++-
>>   accel/tcg/translate-all.c | 2 +-
>>   accel/tcg/translator.c    | 2 +-
>>   3 files changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
>> index 70ea3c7d68..2206c463f5 100644
>> --- a/accel/tcg/cpu-exec.c
>> +++ b/accel/tcg/cpu-exec.c
>> @@ -149,7 +149,13 @@ uint32_t curr_cflags(CPUState *cpu)
>>   {
>>       uint32_t cflags = cpu->tcg_cflags;
>>   
>> -    if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
>> +    /*
>> +     * For singlestep and -d nochain, suppress goto_tb so that
>> +     * we can log -d cpu,exec after every TB.
>> +     */
>> +    if (singlestep) {
> 
> Hmm we are testing a magic global here and looking at
> cpu->singlestep_enabled lower down. We have a transient singlestep which
> is turned on an off via cpu->singlestep_enabled and a global as a debug
> option. Can we rationalise it further?

Not sure what you're asking.

cpu->singlestep_enabled raises a debug exception after one insn, whereas singlestep merely 
exits the tb after one insn.

What is it that you want me to rationalize?


r~