Separate beaglebone kernel build

src/freedombone-image-customise

 cd /root/$PROJECT_NAME
 git checkout bashrc/stretch
 make install
+cp image_build/bbb-4.9.0.tar.gz /boot/bbb.tar.gz
 EOF
 
 chroot "$rootdir" ${PROJECT_NAME}-image-hardware-setup 2>&1 | \

src/freedombone-image-hardware-setup

     initRd=initrd.img-$version
     vmlinuz=vmlinuz-$version
 
+    # optionally use a separately compiled kernel
+    bbb_dtb_file=/usr/lib/$kernelVersion/${bbb_dtb}.dtb
+    if [ -f /boot/bbb.tar.gz ]; then
+        cd /boot
+        tar -xzvf /boot/bbb.tar.gz
+        if [ -f /boot/bbb/dtbs/${bbb_dtb}.dtb ]; then
+            if [ -f /boot/bbb/zImage ]; then
+                bbb_dtb_file=/boot/bbb/dtbs/${bbb_dtb}.dtb
+                vmlinuz=/boot/bbb/zImage
+            fi
+        fi
+    fi
+
     mkdir /tmp/initrd-repack
 
     (cd /tmp/initrd-repack ; \
     rm -rf /tmp/initrd-repack
 
     (cd /boot ; \
-     cp /usr/lib/$kernelVersion/${bbb_dtb}.dtb dtb ; \
+     cp ${bbb_dtb_file} dtb ; \
      cat $vmlinuz dtb >> temp-kernel ; \
      mkimage -A arm -O linux -T kernel -n "Debian kernel ${version}" \
              -C none -a 0x82000000 -e 0x82000000 -d temp-kernel uImage ; \