Re: [PATCH 1/1] auto disable cross for kmod build against distro kernels

[Jan Kiszka <jan.kiszka@siemens.com>]

On 18.01.24 11:31, Felix Moessbauer wrote:
> Cross compiling kernel modules for distro kernels is not supported in debian.
> To simplify downstream kernel module builds, we automatically turn off cross
> compilation for a user-provided module when building it for a distro kernel.
> 
> This patch further replaces the hard-coded list of distro kernels with
> the DISTRO_KERNELS variable to avoid code duplication.
> 
> Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
> ---
>  RECIPE-API-CHANGELOG.md                       |  6 +++++
>  .../example-module/example-module.bb          | 22 -------------------
>  meta/recipes-kernel/linux-module/module.inc   | 10 +++++++++
>  3 files changed, 16 insertions(+), 22 deletions(-)
> 
> diff --git a/RECIPE-API-CHANGELOG.md b/RECIPE-API-CHANGELOG.md
> index bea12871..b1e5a5ab 100644
> --- a/RECIPE-API-CHANGELOG.md
> +++ b/RECIPE-API-CHANGELOG.md
> @@ -566,3 +566,9 @@ supported, but a warning is issued when it is used. Future versions will drop
>  When building a custom kernel module, the `KBuild` file might be located in
>  a subdirectory. To support this use-case, set `MODULE_DIR=$(PWD)/subdir` in
>  the module build recipe.
> +
> +### Automatically disable cross for kmod builds against distro kernels
> +
> +Cross compiling kernel modules for distro kernels is not supported in debian.
> +To simplify downstream kernel module builds, we automatically turn of cross
> +compilation for a user-provided module when building it for a distro kernel.
> diff --git a/meta-isar/recipes-kernel/example-module/example-module.bb b/meta-isar/recipes-kernel/example-module/example-module.bb
> index 5ebed102..22f3cc47 100644
> --- a/meta-isar/recipes-kernel/example-module/example-module.bb
> +++ b/meta-isar/recipes-kernel/example-module/example-module.bb
> @@ -5,28 +5,6 @@
>  #
>  # SPDX-License-Identifier: MIT
>  
> -# Cross-compilation is not supported for the default Debian kernels.
> -# For example, package with kernel headers for ARM:
> -#   linux-headers-armmp
> -# has hard dependencies from linux-compiler-gcc-4.8-arm, what
> -# conflicts with the host binaries.
> -python() {
> -    if d.getVar('KERNEL_NAME') in [
> -        'armmp',
> -        'arm64',
> -        'rpi-rpfv',
> -        'amd64',
> -        '686-pae',
> -        '4kc-malta',
> -        'riscv64',
> -        'kernel',
> -        'kernel7',
> -        'kernel7l',
> -        'kernel8',
> -    ]:
> -        d.setVar('ISAR_CROSS_COMPILE', '0')
> -}
> -
>  require recipes-kernel/linux-module/module.inc
>  
>  SRC_URI += "file://src"
> diff --git a/meta/recipes-kernel/linux-module/module.inc b/meta/recipes-kernel/linux-module/module.inc
> index 269da6ae..eddbf177 100644
> --- a/meta/recipes-kernel/linux-module/module.inc
> +++ b/meta/recipes-kernel/linux-module/module.inc
> @@ -28,6 +28,16 @@ SRC_URI += "file://debian/"
>  
>  AUTOLOAD ?= ""
>  
> +# Cross-compilation is not supported for the default Debian kernels.
> +# For example, package with kernel headers for ARM:
> +#   linux-headers-armmp
> +# has hard dependencies from linux-compiler-gcc-4.8-arm, what
> +# conflicts with the host binaries.
> +python() {
> +    if d.getVar('KERNEL_NAME') in d.getVar('DISTRO_KERNELS').split():
> +        d.setVar('ISAR_CROSS_COMPILE', '0')
> +}
> +

What do we do if this changes one day, in trixie e.g? Or is even fixed
for bookworm?

Jan

>  inherit dpkg
>  
>  TEMPLATE_FILES = "debian/control.tmpl \

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