Include prune.config to reduce kernel Image size (#1245)

Added prune.config to KBUILD_CONFIG_EXTRA for aarch64 builds to
disable non-target architectures configurations, thus significantly
reducing kernel size.

Author: lumag

recipes-kernel/linux/linux-qcom-next_git.bb

@@ -36,13 +36,13 @@ S = "${UNPACKDIR}/${BP}"
 KBUILD_DEFCONFIG ?= "defconfig"
 KBUILD_DEFCONFIG:qcom-armv7a = "qcom_defconfig"
 
-CONFIG_LIST =  "${@" ".join(find_cfgs(d))}"
-CONFIG_LIST += "${@bb.utils.contains('DISTRO_FEATURES', 'hardened', '${S}/kernel/configs/hardening.config', '', d)}"
+KBUILD_CONFIG_EXTRA = "${@bb.utils.contains('DISTRO_FEATURES', 'hardened', '${S}/kernel/configs/hardening.config', '', d)}"
+KBUILD_CONFIG_EXTRA:append:aarch64 = "${S}/arch/arm64/configs/prune.config"
 
 do_configure:prepend() {
     # Use a copy of the 'defconfig' from the actual repo to merge fragments
     cp ${S}/arch/${ARCH}/configs/${KBUILD_DEFCONFIG} ${B}/.config
 
     # Merge fragment for QCOM value add features
-    ${S}/scripts/kconfig/merge_config.sh -m -O ${B} ${B}/.config ${CONFIG_LIST}
+    ${S}/scripts/kconfig/merge_config.sh -m -O ${B} ${B}/.config ${@" ".join(find_cfgs(d))} ${KBUILD_CONFIG_EXTRA}
 }