[Buildroot] [PATCH v4 03/11] package/llvm: enable AMDGPU

Valentin Korenblit valentin.korenblit at smile.fr
Fri Mar 30 11:33:47 UTC 2018


Hello Thomas,

On 30/03/2018 11:02, Thomas Petazzoni wrote:
> Hello Valentin,
>
> On Thu, 29 Mar 2018 13:33:38 +0200, Valentin Korenblit wrote:
>
>> +config BR2_PACKAGE_LLVM_AMDGPU
>> +	bool "AMDGPU backend"
>> +	depends on BR2_PACKAGE_LLVM
>> +	help
>> +	  Build AMDGPU target. Select this option if you are going
>> +	  to install mesa3d with llvm and use Gallium Radeon driver.
>> diff --git a/package/llvm/llvm.mk b/package/llvm/llvm.mk
>> index 4e58c96e0f..c819487bdf 100644
>> --- a/package/llvm/llvm.mk
>> +++ b/package/llvm/llvm.mk
>> @@ -226,9 +226,15 @@ LLVM_CONF_OPTS += -DLLVM_BUILD_EXTERNAL_COMPILER_RT=OFF
>>   # Get target architecture
>>   HOST_LLVM_TARGET_ARCH = $(call qstrip,$(BR2_PACKAGE_LLVM_TARGET_ARCH))
>>   
>> +# Build AMDGPU backend
>> +ifeq ($(BR2_PACKAGE_LLVM_AMDGPU),y)
>> +HOST_LLVM_CONF_OPTS += -DLLVM_TARGETS_TO_BUILD="$(HOST_LLVM_TARGET_ARCH);AMDGPU"
>> +LLVM_CONF_OPTS += -DLLVM_TARGETS_TO_BUILD="$(HOST_LLVM_TARGET_ARCH);AMDGPU"
> It feels non-natural that a target Config.in option
> (BR2_PACKAGE_LLVM_AMDGPU) affect the build of the host variant of the
> LLVM package. Is this really intended and necessary ? I.e do you need
> AMDGPU support in the host LLVM variant for it to work in the target
> LLVM ?
>
As you say, it is a mistake. We don't need amdgpu backend for the host, actually we
need host-llvm just to cross-compile llvm.

>> +else
>>   # Build backend for target architecture
>>   HOST_LLVM_CONF_OPTS += -DLLVM_TARGETS_TO_BUILD="$(HOST_LLVM_TARGET_ARCH)"
>>   LLVM_CONF_OPTS += -DLLVM_TARGETS_TO_BUILD="$(HOST_LLVM_TARGET_ARCH)"
>> +endif
> This doesn't look like a very extensible solution.
>
> What about instead:
>
> LLVM_TARGETS_TO_BUILD = $(HOST_LLVM_TARGET_ARCH)
>
> ifeq ($(BR2_PACKAGE_LLVM_AMDGPU),y)
> LLVM_TARGETS_TO_BUILD := $(LLVM_TARGETS_TO_BUILD);AMDGPU
> endif
>
> and then use LLVM_TARGETS_TO_BUILD to pass -DLLVM_TARGETS_TO_BUILD.

That's much better, I'll do that.

> Best regards,
>
> Thomas

Best regards and thanks for the review,

Valentin



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