Re: [PATCH] linux-custom: Speedup build of target specific linux-kbuild package

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

On 04.06.24 17:39, Stefan Koch wrote:
> Avoids time expensive QEMU-emulated merging of kernel config
> by using a pregenerated kernel config for target specific linux-kbuild
> 

Hmm, it's a bit heavier to install, but we already have the config
packaged: in linux-image under /boot/config-*. Or is this not always the
case?

Jan

> Using DEPENDS instead of RDEPENDS ensures creation of
> pregenerated kernel config before build of target specific linux-kbuild
> 
> Signed-off-by: Stefan Koch <stefan-koch@siemens.com>
> ---
>  .../linux/files/debian/control.tmpl            |  8 ++++++++
>  .../linux/files/debian/isar/common.tmpl        |  2 ++
>  .../linux/files/debian/isar/configure.tmpl     | 18 ++++++++++++++----
>  .../linux/files/debian/isar/install.tmpl       | 15 +++++++++++++++
>  meta/recipes-kernel/linux/linux-custom.inc     | 14 +++++++++-----
>  5 files changed, 48 insertions(+), 9 deletions(-)
> 
> diff --git a/meta/recipes-kernel/linux/files/debian/control.tmpl b/meta/recipes-kernel/linux/files/debian/control.tmpl
> index e0e932a0..fa2b4e12 100644
> --- a/meta/recipes-kernel/linux/files/debian/control.tmpl
> +++ b/meta/recipes-kernel/linux/files/debian/control.tmpl
> @@ -50,6 +50,14 @@ Description: Linux kernel debugging symbols for @KR@
>   This package will come in handy if you need to debug the kernel. It provides
>   all the necessary debug symbols for the kernel and its modules.
>  
> +Package: linux-config-${KERNEL_NAME_PROVIDED}
> +Build-Profiles: <kconfig>
> +Architecture: all
> +Depends: ${perl:Depends}, ${shlib:Depends}
> +Description: ${KERNEL_NAME_PROVIDED} Linux kernel config for @KR@
> + This package provides the kernel config for @KR@
> + The target specific linux-kbuild package benefits from a reduced build time.
> +
>  Package: linux-kbuild-${KERNEL_NAME_PROVIDED}
>  Build-Profiles: <kbuild !cross>
>  Architecture: any
> diff --git a/meta/recipes-kernel/linux/files/debian/isar/common.tmpl b/meta/recipes-kernel/linux/files/debian/isar/common.tmpl
> index 86af70c5..6666c414 100644
> --- a/meta/recipes-kernel/linux/files/debian/isar/common.tmpl
> +++ b/meta/recipes-kernel/linux/files/debian/isar/common.tmpl
> @@ -10,6 +10,7 @@ KERNEL_PKG_IMAGE=linux-image-${KERNEL_NAME_PROVIDED}
>  KERNEL_PKG_KERN_HEADERS=linux-headers-${KERNEL_NAME_PROVIDED}
>  KERNEL_PKG_LIBC_HEADERS=linux-libc-dev
>  KERNEL_PKG_LIBC_HEADERS_CROSS=linux-libc-dev-${DISTRO_ARCH}-cross
> +KERNEL_PKG_KERN_CONFIG=linux-config-${KERNEL_NAME_PROVIDED}
>  KERNEL_PKG_KERN_KBUILD=linux-kbuild-${KERNEL_NAME_PROVIDED}
>  KERNEL_PKG_KERN_KBUILD_CROSS=${KERNEL_PKG_KERN_KBUILD}-${DISTRO_ARCH}-cross
>  
> @@ -32,6 +33,7 @@ deb_dbg_dir=${deb_img_dir}-dbg
>  deb_kern_hdr_dir=${deb_top_dir}/${KERNEL_PKG_KERN_HEADERS}
>  deb_libc_hdr_dir=${deb_top_dir}/${KERNEL_PKG_LIBC_HEADERS}
>  deb_libc_hdr_cross_dir=${deb_top_dir}/${KERNEL_PKG_LIBC_HEADERS_CROSS}
> +deb_kern_config_dir=${deb_top_dir}/${KERNEL_PKG_KERN_CONFIG}
>  deb_kern_kbuild_dir=${deb_top_dir}/${KERNEL_PKG_KERN_KBUILD}
>  deb_kern_kbuild_cross_dir=${deb_top_dir}/${KERNEL_PKG_KERN_KBUILD_CROSS}
>  
> diff --git a/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl b/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl
> index 389c9a85..19797b84 100644
> --- a/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl
> +++ b/meta/recipes-kernel/linux/files/debian/isar/configure.tmpl
> @@ -10,10 +10,20 @@ do_configure() {
>      # Trace what we do here
>      set -x
>  
> -    # 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 ${KERNEL_CONFIG_FRAGMENTS}
> +    configdir=/usr/lib/linux-config-${PV}
> +    if [ -e ${configdir}/kernelconfig ]; then
> +        # Prefer pregenerated kernel config
> +        # So, very expensive QEMU-emulated merge_config.sh
> +        # can be skipped for target specific linux-kbuild package
> +        mkdir -p ${KERNEL_BUILD_DIR}
> +        cp ${configdir}/kernelconfig ${KERNEL_BUILD_DIR}/.config
> +        ${MAKE} O=${KERNEL_BUILD_DIR} olddefconfig
> +    else
> +        # 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 ${KERNEL_CONFIG_FRAGMENTS}
> +    fi
>  
>      # Stop tracing
>      set +x
> diff --git a/meta/recipes-kernel/linux/files/debian/isar/install.tmpl b/meta/recipes-kernel/linux/files/debian/isar/install.tmpl
> index 00011517..3387671c 100644
> --- a/meta/recipes-kernel/linux/files/debian/isar/install.tmpl
> +++ b/meta/recipes-kernel/linux/files/debian/isar/install.tmpl
> @@ -33,6 +33,13 @@ do_install() {
>      # Trace what we do here
>      set -x
>  
> +    if echo "${DEB_BUILD_PROFILES}" | grep -q "kconfig"; then
> +        # Install kernel config
> +        # The target specific linux-kbuild package can speedup
> +        # the build using this pregenerated kernel config
> +        install_kconf ${deb_kern_config_dir}
> +    fi
> +
>      if echo "${DEB_BUILD_PROFILES}" | grep -q "kbuild"; then
>          # Install kernel scripts and tools
>          if echo "${DEB_BUILD_PROFILES}" | grep -q "cross"; then
> @@ -223,6 +230,14 @@ install_headers() {
>      kernel_headers
>  }
>  
> +install_kconf() {
> +    kernel_kconf_dir=usr/lib/linux-config-${PV}
> +    destdir=${1}/${kernel_kconf_dir}
> +
> +    mkdir -p ${destdir}
> +    cp ${O}/${KCONF} ${destdir}/kernelconfig
> +}
> +
>  install_kbuild() {
>      kernel_kbuild_dir=usr/lib/linux-kbuild-${krel}
>      destdir=${1}/${kernel_kbuild_dir}
> diff --git a/meta/recipes-kernel/linux/linux-custom.inc b/meta/recipes-kernel/linux/linux-custom.inc
> index 647f09dd..b21a90f3 100644
> --- a/meta/recipes-kernel/linux/linux-custom.inc
> +++ b/meta/recipes-kernel/linux/linux-custom.inc
> @@ -25,6 +25,7 @@ KBUILD_DEPENDS ?= "build-essential:native, \
>                     flex, \
>                     git, \
>                     kmod, \
> +                   linux-config-${KERNEL_NAME_PROVIDED} <kbuild !kconfig>, \
>                     rsync,"
>  
>  KERNEL_DEBIAN_DEPENDS ?= "initramfs-tools | linux-initramfs-tool, \
> @@ -106,14 +107,14 @@ python() {
>  }
>  
>  # Default profiles and provides
> -BUILD_PROFILES = "kernel kbuild"
> +BUILD_PROFILES = "kernel kconfig kbuild"
>  
>  # We only offer the -kbuildtarget variant when actually cross compiling
>  BBCLASSEXTEND:append:cross-profile = " kbuildtarget"
>  
>  # When cross-profile is active:
> -# build only kernel with the default variant of the recipe
> -BUILD_PROFILES:cross-profile = "kernel"
> +# build only kernel and package config with the default variant of the recipe
> +BUILD_PROFILES:cross-profile = "kernel kconfig"
>  
>  # -native: kbuild package for host
>  BUILD_PROFILES:class-native = "kbuild"
> @@ -122,14 +123,17 @@ RECIPE_PROVIDES:class-native = " \
>      linux-kbuild-${KERNEL_NAME_PROVIDED}"
>  # Use pseudo target to pull in the base variant of the recipe.
>  # Will be auto-extended with -native by multiarch.bbclass.
> -RDEPENDS:class-native += "${BPN}-pseudo"
> +# Using DEPENDS, see below
> +DEPENDS:class-native += "${BPN}-pseudo"
>  
>  # -kbuildtarget: kbuild package for target, enforcing non-cross-build
>  BUILD_PROFILES:class-kbuildtarget = "kbuild"
>  RECIPE_PROVIDES:class-kbuildtarget = " \
>      linux-headers-${KERNEL_NAME_PROVIDED} \
>      linux-kbuild-${KERNEL_NAME_PROVIDED}"
> -RDEPENDS:class-kbuildtarget = "${BPN}"
> +# Using DEPENDS instead of RDEPENDS to ensure creation of pregenerated
> +# kernel config before build of target specific linux-kbuild package
> +DEPENDS:class-kbuildtarget = "${BPN}"
>  ISAR_CROSS_COMPILE:class-kbuildtarget = "0"
>  
>  # Make bitbake know we will be producing linux-image and linux-headers packages

-- 
Siemens AG, Technology
Linux Expert Center