[Buildroot] [PATCH 2/4] llvm: enable bpf

Fabrice Fontaine fontaine.fabrice at gmail.com
Sat Nov 3 14:45:15 UTC 2018


Dear Valentin,
Le sam. 3 nov. 2018 à 15:24, Valentin Korenblit
<valentinkorenblit at gmail.com> a écrit :
>
> Fabrice, Thomas,
>
> Dear Thomas,
> Le sam. 3 nov. 2018 à 14:14, Thomas Petazzoni
> <thomas.petazzoni at bootlin.com> a écrit :
>
> Hello,
>
> On Sat,  3 Nov 2018 13:27:56 +0100, Fabrice Fontaine wrote:
>
> BPF (in-kernel bytecode machine) is needed by libv4l
>
> Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>
> ---
>  package/llvm/llvm.mk | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/package/llvm/llvm.mk b/package/llvm/llvm.mk
> index 1f9bd447f5..dae5d3f16d 100644
> --- a/package/llvm/llvm.mk
> +++ b/package/llvm/llvm.mk
> @@ -54,6 +54,9 @@ ifeq ($(BR2_PACKAGE_LLVM_AMDGPU),y)
>  LLVM_TARGETS_TO_BUILD += AMDGPU
>  endif
>
> +# Build BPF (in-kernel bytecode machine)
> +LLVM_TARGETS_TO_BUILD += BPF
>
> Perhaps we should make this optional ? Or maybe the build time
> difference is not that significant ?
>
> llvm and clang are already taking a long time to build on my "old"
> machine, I didn't notice a significant difference with or without BPF
> but I didn't measure it.
>
> I think we should add a new option just like we did with AMDGPU backend
> as we said we were only going to build backend for target archictecture
> by default.
I would like some advice to add this option, this BPF option should be
selectable even if BR2_PACKAGE_LLVM is not set as llvm is not needed
on the target.

So should I put some kind of hidden option like:
config BR2_PACKAGE_HOST_LLVM_TARGET_BPF
        bool

and select it in libv4l/Config.in?
>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com
>
> Best Regards,
>
> Fabrice
>
> Best regards,
>
> Valentin
Best Regards,

Fabrice



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