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Date:   Sun, 17 Jul 2022 14:48:04 -0300
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Subject: Re: [PATCH v5 4/9] drm: selftest: convert drm_format selftest to
 KUnit
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To:     Daniel Latypov <dlatypov@google.com>,
        Guenter Roeck <linux@roeck-us.net>
Cc:     Isabella Basso <isabbasso@riseup.net>, magalilemes00@gmail.com,
        tales.aparecida@gmail.com, mwen@igalia.com, andrealmeid@riseup.net,
        siqueirajordao@riseup.net, Trevor Woerner <twoerner@gmail.com>,
        leandro.ribeiro@collabora.com, n@nfraprado.net,
        Daniel Vetter <daniel@ffwll.ch>,
        Shuah Khan <skhan@linuxfoundation.org>,
        David Airlie <airlied@linux.ie>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        michal.winiarski@intel.com,
        Javier Martinez Canillas <javierm@redhat.com>,
        =?UTF-8?B?Sm9zw6kgRXhww7NzaXRv?= <jose.exposito89@gmail.com>,
        David Gow <davidgow@google.com>, brendanhiggins@google.com,
        kunit-dev@googlegroups.com, linux-kselftest@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <20220708203052.236290-1-maira.canal@usp.br>
 <20220708203052.236290-5-maira.canal@usp.br>
 <20220714235137.GA485839@roeck-us.net>
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From:   =?UTF-8?Q?Ma=c3=adra_Canal?= <maira.canal@usp.br>
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On 7/14/22 21:03, Daniel Latypov wrote:
> On Thu, Jul 14, 2022 at 4:51 PM Guenter Roeck <linux@roeck-us.net> wrote:
>>
>> On Fri, Jul 08, 2022 at 05:30:47PM -0300, Maíra Canal wrote:
>>> Considering the current adoption of the KUnit framework, convert the
>>> DRM format selftest to the KUnit API.
>>>
>>> Tested-by: David Gow <davidgow@google.com>
>>> Acked-by: Daniel Latypov <dlatypov@google.com>
>>> Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
>>> Signed-off-by: Maíra Canal <maira.canal@usp.br>
>>
>> This patch results in:
>>
>> Building powerpc:allmodconfig ... failed
>> --------------
>> Error log:
>> drivers/gpu/drm/tests/drm_format_test.c: In function 'igt_check_drm_format_min_pitch':
>> drivers/gpu/drm/tests/drm_format_test.c:271:1: error: the frame size of 3712 bytes is larger than 2048 bytes
>>
>> presumably due to function nesting.
> 
> This can happen when there's a lot of KUNIT_EXPECT_* calls in a single function.
> See [1] for some related context.
> There were a number of patches that went into 5.18 ([2] and others) to
> try and mitigate this, but it's not always enough.
> 
> Ideally the compiler would see that the stack-local variables used in
> these macros don't need to stick around, but it doesn't always
> happen...

As a matter of fact, for GCC 12, the warning -Wframe-larger-than=
doesn't show up due to compiler improvement, but for GCC 11.3, it does.

As I have GCC 12 on my machine, I didn't even get the warning.

Anyway, I'll separate the test into multiple functions to avoid any
problems related to stack size.

Best Regards,
- Maíra Canal

> One workaround would be to split up the test case functions into smaller chunks.
> 
> [1] https://lore.kernel.org/linux-kselftest/20210929212713.1213476-1-brendanhiggins@google.com/
> [2] https://lore.kernel.org/linux-kselftest/20220113165931.451305-1-dlatypov@google.com/
> 
> Daniel