Re: [PATCH] meta: kernel: Make specifying KERNEL_CONFIG_FRAGMENTS more flexible

[Zhihang Wei <wzh@ilbers.de>]

On 3/23/26 08:03, 'Jan Kiszka' via isar-users wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
>
> This allows to add kernel config fragments from other sources than just
> individual files in SRC_URI.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>
> isar-cip-core will first use this, currently externalizing part of its
> in-tree fragments to the cip-kernel-config repo.
>
>   RECIPE-API-CHANGELOG.md                       |  9 +++++
>   meta/classes-recipe/linux-kernel.bbclass      | 37 ++++++++++++-------
>   .../linux/files/debian/isar/configure.tmpl    |  2 +-
>   3 files changed, 33 insertions(+), 15 deletions(-)
>
> diff --git a/RECIPE-API-CHANGELOG.md b/RECIPE-API-CHANGELOG.md
> index e44b4b9d..2eff4fc3 100644
> --- a/RECIPE-API-CHANGELOG.md
> +++ b/RECIPE-API-CHANGELOG.md
> @@ -972,3 +972,12 @@ we introduce the variables ``MMAPTOPT_NOEXPKEYSIGN`` and ``DISTRO_MM_OPTS``.
>   While the former provides an argument to disable the key expiry checking, the
>   latter allows users to inject custom options into ``mmdebstrap``. For details,
>   see ``man mmdebstrap``. Use with care!
> +
> +### Provide additional fragments via KERNEL_CONFIG_FRAGMENTS
> +
> +Custom kernel builds can now inject config fragments into the build which were
> +not provided via individual SRC_URI entries. If a kernel source tree contains a
> +fragment, this can be specified via adding `${S}/path/to/fragment.cfg` to
> +`KERNEL_CONFIG_FRAGMENTS`. If a fragment was checked out into ${WORKDIR} as
> +part of a repository, a tarball, or some other directory structure, just
> +specify it relative to ${WORKDIR} in `KERNEL_CONFIG_FRAGMENTS`.
> diff --git a/meta/classes-recipe/linux-kernel.bbclass b/meta/classes-recipe/linux-kernel.bbclass
> index 6e383408..9429996f 100644
> --- a/meta/classes-recipe/linux-kernel.bbclass
> +++ b/meta/classes-recipe/linux-kernel.bbclass
> @@ -83,7 +83,7 @@ TEMPLATE_VARS += "                \
>       KERNEL_LIBC_DEV_ARCH          \
>       LINUX_VERSION_EXTENSION       \
>       KERNEL_NAME_PROVIDED          \
> -    KERNEL_CONFIG_FRAGMENTS       \
> +    KCONFIG_FRAGMENTS             \
>       KCFLAGS                       \
>       KAFLAGS                       \
>       DISTRIBUTOR                   \
> @@ -214,8 +214,10 @@ KERNEL_ARCH ??= "${@get_kernel_arch(d)}"
>   # set KERNEL_FILE without depending on package arch used in bitbake.conf
>   KERNEL_FILE:forcevariable = "${@ 'vmlinux' if d.getVar('KERNEL_ARCH') in ['mipsel', 'riscv', 'arm64'] else 'vmlinuz'}"
>   
> +KERNEL_CONFIG_FRAGMENTS ?= ""
> +
>   def config_fragments(d):
> -    fragments = []
> +    fragments = d.getVar('KERNEL_CONFIG_FRAGMENTS').split()
>       sources = d.getVar("SRC_URI").split()
>       for s in sources:
>           _, _, local, _, _, parm = bb.fetch.decodeurl(s)
> @@ -284,17 +286,21 @@ def get_kernel_config_target(d):
>   
>       return config_target
>   
> -def get_kernel_config_fragments(d):
> -    src_frags = " ".join(config_fragments(d))
> -    out_frags = " ".join(map(lambda frag: 'debian/fragments/' + frag, config_fragments(d)))
> -
> -    linux_version_extension = d.getVar('LINUX_VERSION_EXTENSION')
> -    if linux_version_extension:
> -        out_frags += " debian/isar/version.cfg"
> +KERNEL_CONFIG_FRAGMENTS:append = " \
> +    ${@'${S}/debian/isar/version.cfg' if d.getVar('LINUX_VERSION_EXTENSION') else ''}"
>   
> -    return out_frags
> +def get_kernel_config_fragments(d):
> +    out_frags = ""
> +    S = d.getVar('S') + '/'
> +    for frag in config_fragments(d):
> +        if frag.startswith(S):
> +            out_frags += ' ' + frag[len(S):]
> +        else:
> +            out_frags += ' debian/fragments/' + frag
> +    return out_frags.strip()
>   
> -KERNEL_CONFIG_FRAGMENTS = "${@get_kernel_config_fragments(d)}"
> +# internal list of config fragments
> +KCONFIG_FRAGMENTS = "${@get_kernel_config_fragments(d)}"
>   
>   dpkg_configure_kernel() {
>   	grep -q "KERNEL_CONFIG_TARGET=" ${S}/debian/isar/configure ||
> @@ -313,9 +319,12 @@ EOF
>   	src_frags="${@ " ".join(config_fragments(d)) }"
>   	rm -rf ${S}/debian/fragments
>   	for frag in ${src_frags}; do
> -		basedir=$(dirname ${frag})
> -		mkdir -p ${S}/debian/fragments/${basedir}
> -		cp ${WORKDIR}/${frag} ${S}/debian/fragments/${basedir}/
> +		# skip frag if it starts with ${S}, thus is part of the sources
> +		if [ "${frag#${S}}" = "$frag" ]; then
> +			basedir=$(dirname ${frag})
> +			mkdir -p ${S}/debian/fragments/${basedir}
> +			cp ${WORKDIR}/${frag} ${S}/debian/fragments/${basedir}/
> +		fi
>   	done
>   }
>   
> diff --git a/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl b/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl
> index 73f554ed..75c920b8 100644
> --- a/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl
> +++ b/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl
> @@ -26,7 +26,7 @@ do_configure() {
>           # Process kernel config target and fragments
>           ${MAKE} O=${KERNEL_BUILD_DIR} ${KERNEL_CONFIG_TARGET}
>           ./scripts/kconfig/merge_config.sh -O ${KERNEL_BUILD_DIR}/ \
> -            ${KERNEL_BUILD_DIR}/.config ${KERNEL_CONFIG_FRAGMENTS}
> +            ${KERNEL_BUILD_DIR}/.config ${KCONFIG_FRAGMENTS}
>       fi
>   
>       # Stop tracing
Could you add a test case for this usage?

Zhihang

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