buildCurrentSymlinkedKernel: add support for chroot build

Save config to /etc/kernelconf and use it for rebuilds. this should
prevent raceconditions between enabling a feature and rebooting and
upgrading the kernel. (the upgraded kernel should no be based on the new
feature build.)

buildCurrentSymlinkedKernel.sh

@@ -3,6 +3,8 @@
 SRC_TREE="/usr/src/linux"
 SRC_CONFIG=".config"
 
+CONFIGDIR="/etc/kernelconf"
+
 declare -a OUT
 
 umask 022
@@ -18,10 +20,11 @@ if [[ "$1" == "--force" ]] ; then
   FORCE="1"
 fi
 
-if [[ -f /proc/config.gz ]] ; then
-  OLDCONFIG="1"
-fi
-
+for config in "/proc/config.gz" "$CONFIGDIR/latest" ; do
+  if [[ -f "$config" ]] ; then
+    OLDCONFIG="$config"
+  fi
+done
 
 if [[ "$NOCONFIG" || "$FORCE" ]]  ; then
   echo "**************** building kernel  ***********"
@@ -29,10 +32,10 @@ if [[ "$NOCONFIG" || "$FORCE" ]]  ; then
   TIMESTAMP=$(date +%F-%H_%M_%S)
 
   if [[ "$NOCONFIG" ]] ; then
-    if [[ "$OLDCONFIG" ]] ; then
+    if [[ -n "$OLDCONFIG" ]] ; then
       OUT+=("********** Using old config ************")
       echo "${OUT[-1]}"
-      zcat /proc/config.gz > .config
+      zcat -f "$config" > .config
     else
       OUT+=("********** WARNING! No old config has been found! Using defconfig! ************")
       echo "${OUT[-1]}"
@@ -68,7 +71,14 @@ if [[ "$NOCONFIG" || "$FORCE" ]]  ; then
   echo Summary:
   IFS=$'\n' echo -e "${OUT[*]}"
   echo diff between current running und last build config:
-  diff .config <(zcat /proc/config.gz )
+  diff .config <(zcat -f "${OLDCONFIG}" )
+
+  if [[ -d "$CONFIGDIR" ]] ; then
+    VERSIONSTRING=$(basename $(realpath $(pwd)))
+    TARGET="$CONFIGDIR/${VERSIONSTRING}_$(date --iso=minutes)"
+    cp .config "$TARGET"
+    ln -f -rs "$TARGET" "$CONFIGDIR/latest"
+  fi
 
 fi