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[2/3] drm/amdgpu: Temporarily disable broken Clang builds due to blown stack-frame

Message ID 20221125092517.3074989-3-lee@kernel.org
State New
Headers
Series Fix a bunch of allmodconfig errors |

Commit Message

Lee Jones Nov. 25, 2022, 9:25 a.m. UTC 
  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>
---
 drivers/gpu/drm/Kconfig | 7 +++++++
 1 file changed, 7 insertions(+)

Comments

Arnd Bergmann Nov. 25, 2022, 10:06 a.m. UTC | #1 
On Fri, Nov 25, 2022, at 10:25, 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>
> ---
>  drivers/gpu/drm/Kconfig | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 34f5a092c99e7..1fa7b9760adb8 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -265,6 +265,7 @@ source "drivers/gpu/drm/radeon/Kconfig"
> 
>  config DRM_AMDGPU
>  	tristate "AMD GPU"
> +	depends on BROKEN || !CC_IS_CLANG || !(X86_64 || SPARC64 || ARM64)

The logic looks fine, this has been broken for so long without anyone
paying attention that limiting the broken code to the working architectures
is probably the best way to avoid trouble.

However, as far as I can tell, the problem doesn't affect the
entire driver, only the "new" display engine, so I would probably
try to limit this to turning off CONFIG_DRM_AMD_DC for architectures
that don't have a fixed clang.

     Arnd
diff mbox series

Patch

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 34f5a092c99e7..1fa7b9760adb8 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -265,6 +265,7 @@  source "drivers/gpu/drm/radeon/Kconfig"
 
 config DRM_AMDGPU
 	tristate "AMD GPU"
+	depends on BROKEN || !CC_IS_CLANG || !(X86_64 || SPARC64 || ARM64)
 	depends on DRM && PCI && MMU
 	select FW_LOADER
 	select DRM_DISPLAY_DP_HELPER
@@ -289,6 +290,12 @@  config DRM_AMDGPU
 	help
 	  Choose this option if you have a recent AMD Radeon graphics card.
 
+	  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.
+
 	  If M is selected, the module will be called amdgpu.
 
 source "drivers/gpu/drm/amd/amdgpu/Kconfig"