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From:   Rob Herring <robh@kernel.org>
Date:   Thu, 3 Jun 2021 14:54:03 -0500
Message-ID: <CAL_JsqLF6WhsoSWtxVUqUPDRMM8qwGwZqWa_xtNqsVyq8OCz6w@mail.gmail.com>
Subject: Re: [PATCH 3/3] drm/pl111: depend on CONFIG_VEXPRESS_CONFIG
To:     Kees Cook <keescook@chromium.org>
Cc:     Dave Airlie <airlied@redhat.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Arnd Bergmann <arnd@kernel.org>,
        kernel test robot <lkp@intel.com>,
        Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
        Emma Anholt <emma@anholt.net>, Rob Clark <robdclark@gmail.com>,
        Sean Paul <sean@poorly.run>,
        Linus Walleij <linus.walleij@linaro.org>,
        Sam Ravnborg <sam@ravnborg.org>, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org,
        freedreno@lists.freedesktop.org
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On Thu, Jun 3, 2021 at 1:42 PM Rob Herring <robh@kernel.org> wrote:
>
> On Wed, Jun 2, 2021 at 4:53 PM Kees Cook <keescook@chromium.org> wrote:
> >
> > Avoid randconfig build failures by requiring VEXPRESS_CONFIG:
> >
> > aarch64-linux-gnu-ld: drivers/gpu/drm/pl111/pl111_versatile.o: in function `pl111_vexpress_clcd_init':
> > pl111_versatile.c:(.text+0x220): undefined reference to `devm_regmap_init_vexpress_config'
>
> pl111_vexpress_clcd_init() starts with:
>
> if (!IS_ENABLED(CONFIG_VEXPRESS_CONFIG))
>                 return -ENODEV;
>
> Isn't that supposed to be enough to avoid an undefined reference?
>
> Making the whole file depend on VEXPRESS_CONFIG is not right either.
> Not all platforms need it.

Specifically, these defconfigs will break as they all use PL111 but
don't need nor enable VEXPRESS_CONFIG:

arch/arm/configs/integrator_defconfig:CONFIG_DRM_PL111=y
arch/arm/configs/lpc18xx_defconfig:CONFIG_DRM_PL111=y
arch/arm/configs/lpc32xx_defconfig:CONFIG_DRM_PL111=y
arch/arm/configs/nhk8815_defconfig:CONFIG_DRM_PL111=y
arch/arm/configs/realview_defconfig:CONFIG_DRM_PL111=y
arch/arm/configs/spear3xx_defconfig:CONFIG_DRM_PL111=y
arch/arm/configs/versatile_defconfig:CONFIG_DRM_PL111=y

These defconfigs should all be failing with the same error, but don't
from what I've tried nor have I seen any kernelci failures.

Rob