Try to build a special package and copy the vmlinux, built as a side effect

.buildbot/openwrt/build.sh

@@ -49,6 +49,7 @@ make package/nvme-cli/compile
 make package/ansible-core/compile
 ${MAKE} package/asterisk-chan-quectel/compile
 ${MAKE} package/collectd/compile
+${MAKE} package/kernel-custom/compile
 
 sdkdir=$(pwd)
 cd ${pwd}
@@ -112,7 +113,8 @@ PACKAGES="kmod-i2c-bcm2835 kmod-i2c-mux kmod-i2c-mux-pinctrl \
 
 BOOTSOURCE=target/linux/${OPENWRT_TARGET}/image
 BOOTCONFIG=${BOOTSOURCE}/config.txt
-KERNELSOURCE=build_dir/target-${PKG_ARCH}_musl/linux-${OPENWRT_TARGET}_${OPENWRT_DEVICE}/linux-5.10.146
+KERNELDIR=build_dir/target-${PKG_ARCH}_musl/linux-${OPENWRT_TARGET}_${OPENWRT_DEVICE}
+KERNELSOURCE=${KERNELDIR}/linux-5.10.146
 OVERLAYSOURCE=${KERNELSOURCE}/arch/arm64/boot/dts/overlays
 
 # Setup files
@@ -150,10 +152,12 @@ make image PROFILE=${PROFILE} EXTRA_IMAGE_NAME="dualeth" \
 sed -i "s|,i2c_csi_dsi||g" ${BOOTSOURCE}/current.txt
 sed -i "s/CONFIG_TARGET_ROOTFS_PARTSIZE=.*/CONFIG_TARGET_ROOTFS_PARTSIZE=768/g" .config
 
+cp ${sdkdir}/${KERNELDIR}/vmlinux ${KERNELDIR}/${PROFILE}-kernel.bin
+
 make image PROFILE=${PROFILE} EXTRA_IMAGE_NAME="waveshare" \
      PACKAGES=" \
 	${PACKAGES} cryptsetup kmod-ata-ahci smartmontools hdparm fdisk parted \
-	kmod-hwmon-drivetemp btrfs-progs kmod-fs-btrfs kmod-nvme nvme-cli \
+	kmod-hwmon-drivetemp btrfs-progs kmod-fs-btrfs nvme-cli \
         docker dockerd docker-compose block-mount" \
      DISABLED_SERVICES="dropbear" FILES="files" || exit 1
 

feed/kernel-custom/Makefile

@@ -0,0 +1,69 @@
+#
+# Copyright (C) 2006-2010 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+include $(TOPDIR)/rules.mk
+include $(INCLUDE_DIR)/kernel.mk
+
+PKG_NAME:=kernel-custom
+PKG_FLAGS:=hold
+
+PKG_BUILD_DIR:=$(KERNEL_BUILD_DIR)/packages
+SUBTARGETS = $(sort $(filter-out feeds,$(notdir $(wildcard $(TOPDIR)/target/linux/* $(TOPDIR)/target/linux/feeds/*))))
+SUBTARGET_MODULES = $(foreach t,$(SUBTARGETS),$(firstword $(wildcard $(TOPDIR)/target/linux/feeds/$(t)/modules.mk $(TOPDIR)/target/linux/$(t)/modules.mk)))
+SCAN_DEPS=modules/*.mk $(SUBTARGET_MODULES) $(TOPDIR)/include/netfilter.mk
+
+PKG_LICENSE:=GPL-2.0
+PKG_LICENSE_FILES:=
+
+export SHELL:=/bin/sh
+.ONESHELL:
+.SHELLFLAGS = -ec
+
+TARGET_BUILD:=1
+
+include $(INCLUDE_DIR)/kernel-build.mk
+include $(INCLUDE_DIR)/package.mk
+
+define Build/Prepare
+endef
+
+define Build/Configure
+endef
+
+define Kernel/CompileModules
+	$(call Kernel/CompileImage)
+endef
+
+define Build/Compile
+	$(call BuildKernel)
+endef
+
+define KernelPackage/depends
+endef
+
+CONFIG_PACKAGE_kernel=y
+define Package/$(PKG_NAME)
+  SECTION:=sys
+  CATEGORY:=Kernel
+  DEFAULT:=y
+  TITLE:=Virtual kernel package
+  VERSION:=$(LINUX_VERSION)-$(LINUX_RELEASE)-$(LINUX_VERMAGIC)
+  URL:=http://www.kernel.org/
+  PKG_FLAGS:=nonshared
+endef
+
+define Package/$(PKG_NAME)/install
+  # nothing to do
+endef
+
+define Package/$(PKG_NAME)/extra_provides
+	sed -e 's,.*/,,' $(LINUX_DIR)/modules.builtin;
+endef
+
+$(eval $(if $(DUMP),,$(call BuildPackage,$(PKG_NAME))))
+
+include $(sort $(wildcard ./modules/*.mk))