Re: [Qemu-devel] [PATCH 6/8] tcg/tci: disable MTTCG if TCI is enabled

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

Philippe Mathieu-Daudé <f4bug@amsat.org> writes:

> Hi Peter,
>
> I think this patch belongs to 2.10, as there is no time to fix TCI +
> MTTCG. Should I RESEND it alone with "for 2.10" subject?
>
> One other option might be disable TCI if MTTCG enabled, but there is
> no ./configure option for MTTCG while there is for TCI.
>
> Regards,
>
> Phil.
>
> On 06/28/2017 10:02 PM, Philippe Mathieu-Daudé wrote:
>> TCI + MTTCG cause strange errors...
>>
>>    $ arm-softmmu/qemu-system-arm -machine raspi2 -cpu cortex-a7 -smp 4 -accel tcg,thread=multi -kernel kernel7.img
>>    qemu-system-arm: Guest expects a stronger memory ordering than the host provides
>>    This may cause strange/hard to debug errors
>>    Segmentation fault (core dumped)

So this isn't TCI enabling MTTCG by accident - this is the user forcing
it when it wouldn't otherwise be enabled. Hence the scary warning...

>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>   configure | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/configure b/configure
>> index c571ad14e5..510f443e06 100755
>> --- a/configure
>> +++ b/configure
>> @@ -6225,7 +6225,11 @@ fi
>>   if test "$target_softmmu" = "yes" ; then
>>     echo "CONFIG_SOFTMMU=y" >> $config_target_mak
>>     if test "$mttcg" = "yes" ; then
>> -    echo "TARGET_SUPPORTS_MTTCG=y" >> $config_target_mak
>> +    if test "$tcg_interpreter" = "yes" ; then
>> +        echo "TCI enabled, disabling MTTCG"
>> +    else
>> +        echo "TARGET_SUPPORTS_MTTCG=y" >> $config_target_mak
>> +    fi
>>     fi
>>   fi
>>   if test "$target_user_only" = "yes" ; then
>>


--
Alex Bennée