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Date:   Sun, 27 Nov 2022 22:52:38 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Lee Jones <lee@kernel.org>
Cc:     arnd@arndb.de, akpm@linux-foundation.org,
        maarten.lankhorst@linux.intel.com, mripard@kernel.org,
        tzimmermann@suse.de, airlied@gmail.com, daniel@ffwll.ch,
        ndesaulniers@google.com, trix@redhat.com, harry.wentland@amd.com,
        sunpeng.li@amd.com, Rodrigo.Siqueira@amd.com,
        alexander.deucher@amd.com, christian.koenig@amd.com,
        Xinhui.Pan@amd.com, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 1/2] drm/amdgpu: Temporarily disable broken Clang
 builds due to blown stack-frame
Message-ID: <Y4RMphf6BUGLA5B6@dev-arch.thelio-3990X>
References: <20221125120750.3537134-1-lee@kernel.org>
 <20221125120750.3537134-2-lee@kernel.org>
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On Fri, Nov 25, 2022 at 12:07:49PM +0000, Lee Jones wrote:
> calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
> architectures built with Clang (all released versions), whereby the stack
> frame gets blown up to well over 5k.  This would cause an immediate kernel
> panic on most architectures.  We'll revert this when the following bug report
> has been resolved: https://github.com/llvm/llvm-project/issues/41896.
> 
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Lee Jones <lee@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  drivers/gpu/drm/amd/display/Kconfig | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
> index 6925e0280dbe6..f4f3d2665a6b2 100644
> --- a/drivers/gpu/drm/amd/display/Kconfig
> +++ b/drivers/gpu/drm/amd/display/Kconfig
> @@ -5,6 +5,7 @@ menu "Display Engine Configuration"
>  config DRM_AMD_DC
>  	bool "AMD DC - Enable new display engine"
>  	default y
> +	depends on BROKEN || !CC_IS_CLANG || X86_64 || SPARC64 || ARM64
>  	select SND_HDA_COMPONENT if SND_HDA_CORE
>  	select DRM_AMD_DC_DCN if (X86 || PPC_LONG_DOUBLE_128)
>  	help
> @@ -12,6 +13,12 @@ config DRM_AMD_DC
>  	  support for AMDGPU. This adds required support for Vega and
>  	  Raven ASICs.
>  
> +	  calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
> +	  architectures built with Clang (all released versions), whereby the stack
> +	  frame gets blown up to well over 5k.  This would cause an immediate kernel
> +	  panic on most architectures.  We'll revert this when the following bug report
> +	  has been resolved: https://github.com/llvm/llvm-project/issues/41896.
> +
>  config DRM_AMD_DC_DCN
>  	def_bool n
>  	help
> -- 
> 2.38.1.584.g0f3c55d4c2-goog
>