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From: Peter Maydell <peter.maydell@linaro.org>
Date: Tue, 9 Oct 2018 12:59:01 +0100
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Subject: Re: [Qemu-devel] [PATCH] linux-user: Suppress
 address-of-packed-member warnings in __get/put_user_e
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To: Laurent Vivier <laurent@vivier.eu>
Cc: Richard Henderson <richard.henderson@linaro.org>, QEMU Developers <qemu-devel@nongnu.org>, Riku Voipio <riku.voipio@iki.fi>, "patches@linaro.org" <patches@linaro.org>

On 5 October 2018 at 17:09, Laurent Vivier <laurent@vivier.eu> wrote:
> On 05/10/2018 17:25, Richard Henderson wrote:
>> On 10/5/18 4:10 AM, Peter Maydell wrote:
>>> On 5 October 2018 at 01:28, Laurent Vivier <laurent@vivier.eu> wrote:
>>>> I have the following error when building on Fedora 28 and gcc (GCC)
>>>> 8.1.1 20180712 (Red Hat 8.1.1-5)
>>>>
>>>>   CC      aarch64_be-linux-user/target/arm/arm-semi.o
>>>> .../target/arm/arm-semi.c: In function =E2=80=98do_arm_semihosting=E2=
=80=99:
>>>> .../target/arm/arm-semi.c:270:1: error: unknown option after =E2=80=98=
#pragma
>>>> GCC diagnostic=E2=80=99 kind [-Werror=3Dpragmas]
>>>>
>>>> Perhaps you should use a "#if defined(__clang__)" to apply your fix on=
ly
>>>> to clang?
>>>
>>> I did test on gcc, but not that version. The point of the
>>>    _Pragma("GCC diagnostic ignored \"-Wpragmas\"");
>>> line is to suppress that error (which it does on my gcc 5)
>>> so I don't know why your gcc is complaining :-(
>>
>> I suppose you could try -Wunknown-pragmas.
>> But from reading the manual it shouldn't make a difference.
>> OTOH, what you wrote should have worked...
>
> Could it be a bug in _Pragma()?

I got an f28 VM and can repro this. It looks like the problem
only happens when the get_user/put_user stuff is used via some
other macro, for some reason -- so the GET_ARG and SET_ARG
macros in arm-semi.c and the NEW_AUX_ENT macro in elfload.c
cause problems, but less indirect use does not. I'll try to
trim this down to a smaller test case somehow...

thanks
-- PMM