From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:37584)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <alex.bennee@linaro.org>) id 1daHGm-0006jQ-GA
	for qemu-devel@nongnu.org; Wed, 26 Jul 2017 04:02:13 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <alex.bennee@linaro.org>) id 1daHGh-0001za-QV
	for qemu-devel@nongnu.org; Wed, 26 Jul 2017 04:02:12 -0400
Received: from mail-wm0-x234.google.com ([2a00:1450:400c:c09::234]:37099)
	by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16)
	(Exim 4.71) (envelope-from <alex.bennee@linaro.org>)
	id 1daHGh-0001zS-Jr
	for qemu-devel@nongnu.org; Wed, 26 Jul 2017 04:02:07 -0400
Received: by mail-wm0-x234.google.com with SMTP id c184so74361185wmd.0
	for <qemu-devel@nongnu.org>; Wed, 26 Jul 2017 01:02:07 -0700 (PDT)
References: <20170629010300.2848-1-f4bug@amsat.org>
	<20170629010300.2848-7-f4bug@amsat.org>
	<9a40c690-0b80-cd34-6129-849703b452e2@amsat.org>
From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
In-reply-to: <9a40c690-0b80-cd34-6129-849703b452e2@amsat.org>
Date: Wed, 26 Jul 2017 09:02:04 +0100
Message-ID: <87a83reidf.fsf@linaro.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
Subject: Re: [Qemu-devel] [PATCH 6/8] tcg/tci: disable MTTCG if TCI is
 enabled
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= <f4bug@amsat.org>
Cc: qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <rth@twiddle.net>, Stefan Weil <sw@weilnetz.de>, Peter Maydell <peter.maydell@linaro.org>, "Emilio G . Cota" <cota@braap.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