kernel plugin: properly generate Ubuntu kernel .config

Recent Ubuntu kernels (>= Jammy) are now using a new format to store
their .config, called annotations [1].

The kernel plugin is trying to assemble a .config using the old config
chunks stored in `debian.<kernel>/config/*` that are not available
anymore in the kernels that are using this new annotations model.

Instead of trying to manually assemble the config we should rely on
`debian/rules genconfigs` that is more portable across different Ubuntu
kernels and releases.

[ Thanks to Guo-Rong for fixing all the test case failures. ]

[1] https://lists.ubuntu.com/archives/kernel-team/2023-June/140230.html

Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

snapcraft_legacy/plugins/v2/_kernel_build.py

@@ -278,17 +278,20 @@ def _do_base_config_cmd(
  logger.info("Using ubuntu config flavour %s", config_flavour)
  conf_cmd = textwrap.dedent(
  """ echo "Assembling Ubuntu config..."
- branch=$(cut -d'.' -f 2- < ${{KERNEL_SRC}}/debian/debian.env)
- baseconfigdir=${{KERNEL_SRC}}/debian.${{branch}}/config
- archconfigdir=${{KERNEL_SRC}}/debian.${{branch}}/config/${{DEB_ARCH}}
- ubuntuconfig=${{baseconfigdir}}/config.common.ubuntu
- archconfig=${{archconfigdir}}/config.common.${{DEB_ARCH}}
- flavourconfig=${{archconfigdir}}/config.flavour.{config_flavour}
- cat ${{ubuntuconfig}} ${{archconfig}} ${{flavourconfig}} \
-> {dest_dir}/.config 2>/dev/null || true
  if [ -f ${{KERNEL_SRC}}/debian/rules ] && [ -x ${{KERNEL_SRC}}/debian/rules ]; then
+ # Generate Ubuntu kernel configs
+ pushd ${{KERNEL_SRC}}
+ fakeroot debian/rules clean genconfigs || true
+ popd
+
+ # Pick the right kernel .config for the target arch and flavour
+ ubuntuconfig=${{KERNEL_SRC}}/CONFIGS/${{DEB_ARCH}}-config.flavour.{config_flavour}
+ cat ${{ubuntuconfig}} > {dest_dir}/.config
+
+ # Clean up kernel source directory
  pushd ${{KERNEL_SRC}}
  fakeroot debian/rules clean
+ rm -rf CONFIGS/
  popd
  fi""".format(
  config_flavour=config_flavour, dest_dir=dest_dir

tests/legacy/unit/plugins/v2/test_kernel.py

@@ -1302,17 +1302,20 @@ def _is_sub_array(array, sub_array):
  "if [ ! -e ${SNAPCRAFT_PART_BUILD}/.config ]; then",
  textwrap.dedent(
  """ echo "Assembling Ubuntu config..."
- branch=$(cut -d'.' -f 2- < ${KERNEL_SRC}/debian/debian.env)
- baseconfigdir=${KERNEL_SRC}/debian.${branch}/config
- archconfigdir=${KERNEL_SRC}/debian.${branch}/config/${DEB_ARCH}
- ubuntuconfig=${baseconfigdir}/config.common.ubuntu
- archconfig=${archconfigdir}/config.common.${DEB_ARCH}
- flavourconfig=${archconfigdir}/config.flavour.raspi
- cat ${ubuntuconfig} ${archconfig} ${flavourconfig} \
-> ${SNAPCRAFT_PART_BUILD}/.config 2>/dev/null || true
  if [ -f ${KERNEL_SRC}/debian/rules ] && [ -x ${KERNEL_SRC}/debian/rules ]; then
+ # Generate Ubuntu kernel configs
+ pushd ${KERNEL_SRC}
+ fakeroot debian/rules clean genconfigs || true
+ popd
+
+ # Pick the right kernel .config for the target arch and flavour
+ ubuntuconfig=${KERNEL_SRC}/CONFIGS/${DEB_ARCH}-config.flavour.raspi
+ cat ${ubuntuconfig} > ${SNAPCRAFT_PART_BUILD}/.config
+
+ # Clean up kernel source directory
  pushd ${KERNEL_SRC}
  fakeroot debian/rules clean
+ rm -rf CONFIGS/
  popd
  fi"""
  ),

tests/unit/parts/plugins/test_kernel.py

@@ -1401,17 +1401,20 @@ def _is_sub_array(array, sub_array):
  "if [ ! -e ${CRAFT_PART_BUILD}/.config ]; then",
  textwrap.dedent(
  """ echo "Assembling Ubuntu config..."
- branch=$(cut -d'.' -f 2- < ${KERNEL_SRC}/debian/debian.env)
- baseconfigdir=${KERNEL_SRC}/debian.${branch}/config
- archconfigdir=${KERNEL_SRC}/debian.${branch}/config/${DEB_ARCH}
- ubuntuconfig=${baseconfigdir}/config.common.ubuntu
- archconfig=${archconfigdir}/config.common.${DEB_ARCH}
- flavourconfig=${archconfigdir}/config.flavour.raspi
- cat ${ubuntuconfig} ${archconfig} ${flavourconfig} \
-> ${CRAFT_PART_BUILD}/.config 2>/dev/null || true
  if [ -f ${KERNEL_SRC}/debian/rules ] && [ -x ${KERNEL_SRC}/debian/rules ]; then
+ # Generate Ubuntu kernel configs
+ pushd ${KERNEL_SRC}
+ fakeroot debian/rules clean genconfigs || true
+ popd
+
+ # Pick the right kernel .config for the target arch and flavour
+ ubuntuconfig=${KERNEL_SRC}/CONFIGS/${DEB_ARCH}-config.flavour.raspi
+ cat ${ubuntuconfig} > ${CRAFT_PART_BUILD}/.config
+
+ # Clean up kernel source directory
  pushd ${KERNEL_SRC}
  fakeroot debian/rules clean
+ rm -rf CONFIGS/
  popd
  fi"""
  ),