[v6,12/14] mesa: use simpler mesa-tools-native recipe as dependency for libclc

From: Quentin Schulz <quentin.schulz@cherry.de>

libclc is required for some drivers (asahi, panfrost and intel at the
very least).
libclc brings very expensive dependencies such as llvm and clang.
Building clang and llvm for each target architecture is very expensive,
but mesa allows to depend on prebuilt host binaries (mesa-clc and
precomp-compiler). Those are built by mesa as well, but can be compiled
in mesa-native instead of mesa, making the dependency expensive but only
once regardless of the number of target architectures to build for.
Ideally the mesa-clc and precomp-compiler would only be compiled in
mesa-native if target mesa requires libclc support, however this is not
possible as a target recipe cannot impact or depend on a native recipe's
configuration. We thus have two choices, always build libclc in
mesa-native with its heavy dependencies and impact every build or force
the user to modify the mesa-native recipe in a custom layer (as a native
recipe cannot use target's OVERRIDES). The latter is unacceptable so the
former seems to be the only option. Another big downside is that
mesa-native currently builds drivers (amd, nouveau, svga) which we may
have absolutely no interest in building, increasing the build time and
possibly dependencies list).

A third choice is to spin-off the native mesa recipe with libclc support
into a new recipe without drivers and only what's necessary to build
mesa-clc and precomp-compiler binaries.
This allows to keep a "clean" mesa-native recipe for whoever needs those
drivers built-in (e.g. for testing, for qemu-native, or whatever else)
and only bring the libclc dependency when required by the target recipe.

Because libclc is now only built for the host, opencl support now needs
to explicitly bring libclc and others to build as libclc won't bring it
in the build environment anymore.

Suggested-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
---
 meta/recipes-graphics/mesa/mesa-tools-native.bb | 19 +++++++++++++++++++
 meta/recipes-graphics/mesa/mesa.inc             | 15 ++++-----------
 2 files changed, 23 insertions(+), 11 deletions(-)

Hi all,

On 8/22/25 2:53 PM, Quentin Schulz wrote:
> From: Quentin Schulz <quentin.schulz@cherry.de>
> 
> libclc is required for some drivers (asahi, panfrost and intel at the
> very least).
> libclc brings very expensive dependencies such as llvm and clang.
> Building clang and llvm for each target architecture is very expensive,
> but mesa allows to depend on prebuilt host binaries (mesa-clc and
> precomp-compiler). Those are built by mesa as well, but can be compiled
> in mesa-native instead of mesa, making the dependency expensive but only
> once regardless of the number of target architectures to build for.
> Ideally the mesa-clc and precomp-compiler would only be compiled in
> mesa-native if target mesa requires libclc support, however this is not
> possible as a target recipe cannot impact or depend on a native recipe's
> configuration. We thus have two choices, always build libclc in
> mesa-native with its heavy dependencies and impact every build or force
> the user to modify the mesa-native recipe in a custom layer (as a native
> recipe cannot use target's OVERRIDES). The latter is unacceptable so the
> former seems to be the only option. Another big downside is that
> mesa-native currently builds drivers (amd, nouveau, svga) which we may
> have absolutely no interest in building, increasing the build time and
> possibly dependencies list).
> 
> A third choice is to spin-off the native mesa recipe with libclc support
> into a new recipe without drivers and only what's necessary to build
> mesa-clc and precomp-compiler binaries.
> This allows to keep a "clean" mesa-native recipe for whoever needs those
> drivers built-in (e.g. for testing, for qemu-native, or whatever else)
> and only bring the libclc dependency when required by the target recipe.
> 
> Because libclc is now only built for the host, opencl support now needs
> to explicitly bring libclc and others to build as libclc won't bring it
> in the build environment anymore.
> 
> Suggested-by: Ross Burton <ross.burton@arm.com>
> Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
> ---
>   meta/recipes-graphics/mesa/mesa-tools-native.bb | 19 +++++++++++++++++++
>   meta/recipes-graphics/mesa/mesa.inc             | 15 ++++-----------
>   2 files changed, 23 insertions(+), 11 deletions(-)
> 
> diff --git a/meta/recipes-graphics/mesa/mesa-tools-native.bb b/meta/recipes-graphics/mesa/mesa-tools-native.bb
> new file mode 100644
> index 0000000000000000000000000000000000000000..dab1a037851cca6b33eae4b69a6a141fbbcd801b
> --- /dev/null
> +++ b/meta/recipes-graphics/mesa/mesa-tools-native.bb
> @@ -0,0 +1,19 @@
> +require mesa.inc
> +inherit native

I think I should have inherit_defer native here instead? To make sure 
regardless of what the user does in a bbappend (well aside from using 
another inherit_defer), native is always the last inherited class?

Cheers,
Quentin