config: add old kernel build capability for development

helpers/config

@@ -49,6 +49,19 @@ export UPSTREAMRELEASE=24.04
 MIRROR=http://archive.ubuntu.com/ubuntu
 LOCALMIRROR=http://archive.trisquel.org/trisquel
 LOCAL_APT=`mktemp -d` 
+if [[ "$PACKAGE" =~ ^linux(-hwe-[0-9]+\.[0-9]+)?$ && -n "$LP_VERSION" ]]; then
+# Function to truncate the version string to the major version (e.g., 6.5.0)
+truncate_version() {
+    full_version=$1
+    # Match the first three components of the version (X.Y.0)
+    echo "$full_version" | sed -E 's/^([^_]+_[0-9]+\.[0-9]+\.0).*/\1/'
+}
+LP_ARCHIVE_URL="https://launchpad.net/ubuntu/+archive/primary/+sourcefiles/${PACKAGE}/${LP_VERSION}"
+TRUNCATED_VERSION=$(truncate_version "${PACKAGE}_${LP_VERSION}")
+LP_TARBALL="${TRUNCATED_VERSION}.orig.tar.gz"
+LP_DIFF_FILE="${PACKAGE}_${LP_VERSION}.diff.gz"
+LP_DSC_FILE="${PACKAGE}_${LP_VERSION}.dsc"
+fi
 
 if [ -n "$BUILD_UNTIL" ] && (( $(echo "$BUILD_UNTIL $REVISION" | awk '{print ($1 > $2)}') )); then
     echo "Skipping build of helper with BUILD_UNTIL=$BUILD_UNTIL > REVISION=$REVISION"
@@ -146,6 +159,15 @@ cd PACKAGES/$PACKAGE
 [ $UID = 0 ] && id _apt > /dev/null 2>&1 && chown _apt .
 
 #Get package and uncompress it
+if [[ "$PACKAGE" =~ ^linux(-hwe-[0-9]+\.[0-9]+)?$ && -n "$LP_VERSION" ]]; then
+    for file in "${LP_TARBALL}" "${LP_DIFF_FILE}" "${LP_DSC_FILE}"; do
+        echo "Downloading ${file} from ${LP_ARCHIVE_URL}"
+        if ! wget "${LP_ARCHIVE_URL}/${file}" -O "${file}"; then
+            echo "Error: Failed to download ${file}."
+            exit 1
+        fi
+    done
+else
     apt-get update -c $LOCAL_APT/etc/apt.conf
     if [ -n "$FIXED_VER" ]; then
       apt-get source --only-source $PACKAGE=$FIXED_VER --download-only -c ${LOCAL_APT}/etc/apt.conf
@@ -163,6 +185,7 @@ else
       echo WARNING! The dsc file is not gpg signed!
       [ -z "$EXTERNAL" ] && exit 1
     fi
+fi
 
 dpkg-source --no-check -x --skip-patches *.dsc source
 
@@ -276,3 +299,4 @@ patch_Rp1() {
 echo "> Rolling back $(echo $1|xargs basename):"
 patch --no-backup-if-mismatch -R -p1 < $1
 }
+