diff --git a/README.md b/README.md
index 4ebb3bf..4928c99 100644
--- a/README.md
+++ b/README.md
@@ -90,11 +90,16 @@ details.
 
 Use the following environment variables:
 
- * WM2_VERBOSE: value from 0 (default, no logging) - 3 (tracing).
+ * `WM2_VERBOSE:` value from 0 (default, no logging) - 3 (tracing).
    the -v/--verbose option increases log level by one.
- * WM2_DEBUG: 0 (default) or 1. Enables verbose output of certain
+ * `WM2_DEBUG`: 0 (default) or 1. Enables verbose output of certain
    commands called by weak-modules2. Equivalent to --debug.
- * WM2_LOGFILE: redirect the output to the given file.
+ * `WM2_LOGFILE`: redirect the output to the given file.
+
+### Other environment variables
+
+ * `WM2_DEPMOD_INC`: set this to a non-empty string to enable the experimental
+   "incremental depmod" feature. This will speed up KMP installations.
 
 ## Kernel scriptlet files
 
diff --git a/kernel-scriptlets/rpm-script b/kernel-scriptlets/rpm-script
index 002fc48..e2687da 100644
--- a/kernel-scriptlets/rpm-script
+++ b/kernel-scriptlets/rpm-script
@@ -281,6 +281,9 @@ EOF
 	[ -z "$certs" ] || /usr/lib/module-init-tools/kernel-scriptlets/cert-$op --ca-check 1 --certs "$certs" "$@"
 	;;
     posttrans)
+	if test -x /usr/lib/module-init-tools/regenerate-initrd-posttrans; then
+	    /bin/bash -c 'set +e; /usr/lib/module-init-tools/regenerate-initrd-posttrans' || script_rc=$?
+	fi
 	;;
     *)
 	echo Unknown scriptlet "$op" >&2
diff --git a/weak-modules2 b/weak-modules2
index 94df90b..e1206f6 100644
--- a/weak-modules2
+++ b/weak-modules2
@@ -113,10 +113,11 @@ doit() {
     else
 	:
     fi
+    log "Done $1"
 }
 
 strip_mod_extensions() {
-    sed -rn '/^_kernel_$/p;s/\.ko(\.[gx]z|\.zst)?$//p'
+    sed -rn 's/\.ko(\.[gx]z|\.zst)?$//p'
 }
 
 # Name of the symlink that makes a module available to a given kernel
@@ -158,9 +159,9 @@ add_kmp_modules() {
     local module symlink
     while read module; do
 	symlink=$(symlink_to_module $module $krel)
-	doit mkdir -p ${opt_debug:+-v} $basedir${symlink%/*} || exit 1
-	doit ln -sf ${opt_debug:+-v} $module $basedir$symlink || exit 1
-	dlog "add_kmp_modules: added $module to $krel"
+	mkdir -p $basedir${symlink%/*} || exit 1
+	ln -sf $module $basedir$symlink || exit 1
+	dlog "add_kmp_modules: added $module to $krel in $basedir"
     done < $tmpdir/modules-$kmp
 }
 
@@ -173,7 +174,7 @@ remove_kmp_modules() {
     local module symlink
     while read module; do
 	symlink=$(symlink_to_module $module $krel)
-	doit rm -f ${opt_debug:+-v} $basedir$symlink
+	rm -f $basedir$symlink
 	dlog "remove_kmp_modules: removed $module from $krel"
     done < $tmpdir/modules-$kmp
 }
@@ -195,7 +196,8 @@ create_temporary_modules_dir() {
 
 # Check for unresolved symbols
 has_unresolved_symbols() {
-    local krel=$1 basedir=$2 output status args sym_errors _f
+    local krel=$1 basedir=$2 kmp=$3 kmp_mods=() inc=
+    local output status args sym_errors _f
 
     if [ ! -e $tmpdir/symvers-$krel ]; then
 	for _f in /boot/symvers-$krel.gz /usr/lib/modules/$krel/symvers.gz; do
@@ -212,8 +214,23 @@ has_unresolved_symbols() {
 	echo "warning: $tmpdir/symvers-$krel not available" >&2
 	args=(-F /boot/System.map-$krel)
     fi
-    output="$("$DEPMOD" -b "$basedir" -ae "${args[@]}" $krel 2>&1)"
+    if [[ $WM2_DEPMOD_INC && $kmp ]]; then
+	inc=-I
+	kmp_mods=($(cat $tmpdir/modules-$kmp))
+	# prepend $basedir
+	kmp_mods=("${kmp_mods[@]/#/$basedir}")
+    fi
+    log "$DEPMOD -b $basedir -ae ${args[@]} $inc $krel ${kmp_mods[@]}"
+    output="$("$DEPMOD" -b "$basedir" -ae "${args[@]}" $inc $krel ${kmp_mods[@]} 2>&1)"
     status=$?
+    log "$DEPMOD finished"
+    if [[ $status -ne 0 && $WM2_DEPMOD_INC && $kmp ]]; then
+	# Fallback to full depmod
+	log "$DEPMOD -b $basedir -ae ${args[@]} $krel"
+	output="$("$DEPMOD" -b "$basedir" -ae "${args[@]}" $krel 2>&1)"
+	status=$?
+	log "$DEPMOD finished"
+    fi
     if [ $status -ne 0 ]; then
 	echo "$output" >&2
 	echo "depmod exited with error $status" >&2
@@ -266,7 +283,7 @@ __can_replace_kmp() {
 	return 1
     fi
     doit=1 add_kmp_modules "$new_kmp" "$krel" "$basedir"
-    if has_unresolved_symbols "$krel" "$basedir"; then
+    if has_unresolved_symbols "$krel" "$basedir" "$new_kmp"; then
 	doit=1 remove_kmp_modules "$new_kmp" "$krel" "$basedir"
 	doit=1 add_kmp_modules "$old_kmp" "$krel" "$basedir"
 	return 1
@@ -372,7 +389,7 @@ previous_version_of_kmp() {
 }
 
 get_initrd_basenames() {
-    $LSINITRD /boot/initrd-$1 | \
+    doit $LSINITRD /boot/initrd-$1 | \
 	sed -rn 's:.*\<lib/modules/.*/::p' | \
 	strip_mod_extensions
 
@@ -382,9 +399,11 @@ get_initrd_basenames() {
 }
 
 # test if rebuilding initrd is needed for $krel.
-# stdin - list of changed modules ("_kernel_" for the whole kernel)
+# arg 1: kernel version
+# arg 2: if non-empty, assume kernel package (must rebuild)
+# stdin - list of changed modules (if arg 2 is empty)
 needs_initrd() {
-    local krel=$1
+    local krel=$1 is_kernel=$2
 
     # Don't generate an initrd for kdump here. It's done automatically with mkdumprd when
     # /etc/init.d/boot.kdump is called to load the kdump kernel. See mkdumprd(8) why
@@ -405,13 +424,14 @@ needs_initrd() {
 	return 0
     fi
 
-    local changed_basenames=($(strip_mod_extensions | sort -u))
-    dlog "needs_initrd: changed_basenames: " $changed_basenames
-
-    if [ "$changed_basenames" = "_kernel_" ]; then
+    if [[ $is_kernel ]]; then
 	dlog "needs_initrd: yes, kernel package"
 	return 0
     fi
+
+    local changed_basenames=($(strip_mod_extensions | sort -u))
+    dlog "needs_initrd: changed_basenames: " $changed_basenames
+
     if [ ! -e /boot/initrd-$krel ]; then
 	dlog "needs_initrd: yes, initrd doesn't exist yet"
 	return 0
@@ -429,25 +449,49 @@ needs_initrd() {
     return 1
 }
 
-# run depmod and rebuild initrd for kernel version $krel
-# stdin - list of changed modules ("_kernel_" for a whole kernel)
-run_depmod_build_initrd() {
-    local krel=$1
-    local status=0
+# run depmod
+# first arg - kernel release; more args - modules to add (if any),
+# will enable depmod incremental mode
+run_depmod() {
+    local krel=$1 inc= status=
 
-    if [ -d /lib/modules/$krel -a -f /boot/System.map-$krel ] ; then
-	doit "$DEPMOD" -F /boot/System.map-$krel -ae $krel || return 1
+    [ -d /lib/modules/$krel -a -f /boot/System.map-$krel ] || \
+	return
+
+    shift
+    if [[ $WM2_DEPMOD_INC && $# -gt 0 ]]; then
+	inc=-I
     fi
-    if needs_initrd $krel; then
-	local image
-	for x in vmlinuz image vmlinux linux bzImage uImage Image zImage; do
-	    if [ -f /boot/$x-$krel ]; then
-		image=$x
-		break
-	    fi
-	done
+    doit "$DEPMOD" -F /boot/System.map-"$krel" -ae $inc "$krel" "$@"
+    status=$?
+    if [[ $status -ne 0 && $inc ]]
+       # fall back to full depmod
+       doit "$DEPMOD" -F /boot/System.map-"$krel" -ae "$krel"
+    fi
+}
+
+get_image_name() {
+    local krel=$1 x
+
+    for x in vmlinuz image vmlinux linux bzImage uImage Image zImage; do
+	if [ -f /boot/"$x-$krel" ]; then
+	    echo "$x"
+	    return
+	fi
+    done
+}
+
+# rebuild initrd for kernel version $krel
+# stdin - list of changed modules
+build_initrd() {
+    local krel=$1 is_kernel=$2 may_delay=$3
+    local status=0
+
+    if needs_initrd $krel $is_kernel; then
+	local image=$(get_image_name "$krel")
+
 	if [ -n "$image" ]; then
-	    if test -n "$INITRD_IN_POSTTRANS"; then
+	    if [[ "$may_delay" ]]; then
 		mkdir -p /run/regenerate-initrd
 		doit touch /run/regenerate-initrd/$image-$krel
 	    else
@@ -498,8 +542,16 @@ walk_kmps() {
     done
 }
 
+# first arg - kernel release
+# 2nd arg: is this a base pkg (-> must rebuild initrd)?
+# 3rd arg: can the initrd build be delayed to %posttrans?
+# other args - modules to add, enables depmod incremental
+# stdin: list of module basenames to feed into build_initrd / needs_initrd
 kernel_changed() {
-    local krel=$1 flavor=${1##*-}
+    local krel=$1 is_basepkg=$2 may_delay=$3 flavor=${1##*-}
+    shift
+    shift
+    shift
 
     if [ ! -f /boot/System.map-$krel ]; then
 	# this kernel does not exist anymore
@@ -514,13 +566,14 @@ kernel_changed() {
 	walk_kmps "$krel"
     fi
 
-    echo "_kernel_" | run_depmod_build_initrd "$krel"
+    run_depmod "$krel" "$@"
+    build_initrd "$krel" "$is_basepkg" "$may_delay"
 }
 
 add_kernel() {
     local krel=$1
 
-    kernel_changed $krel
+    kernel_changed "$krel" initrd_needed "$INITRD_IN_POSTTRANS"
 }
 
 remove_kernel() {
@@ -536,17 +589,58 @@ remove_kernel() {
 
 add_kernel_modules() {
     local krel=$1
-    cat >/dev/null
+    local initrd_needed=yes
+
+    sed -rn '/\.ko(|\.xz|\.gz|\.zst)/p' >$tmpdir/kernel-modules
+    sed 's:.*/::' <$tmpdir/kernel-modules >$tmpdir/kernel-basenames
+
+    # If INITRD_IN_POSTTRANS isn't set, and a kernel base package
+    # is installed / updated together with subpackages, the base package
+    # is processed first. If a module from a subpackage is necessary
+    # in the initrd, it will be missing at that stage, and the initrd
+    # will be built without it. Therefore we need to force initrd rebuild
+    # in that case. If INITRD_IN_POSTTRANS is set, this won't happen, and
+    # we only need to force initrd creation if one of the modules of
+    # our subpkg are present in the initrd.
+    if [[ $INITRD_IN_POSTTRANS ]]; then
+	initrd_needed=
+    fi
+    kernel_changed "$krel" "$initrd_needed" "$INITRD_IN_POSTTRANS" \
+		   $(cat $tmpdir/kernel-modules) \
+		   <$tmpdir/kernel-basenames
+}
+
+# for package deletion, there's no %posttrans, therefore delaying the
+# initrd rebuild is not generally possible. But if some other package
+# has scheduled a rebuild for the given kernel already, we can.
+# (this would happen on a KMP update, for example).
+may_delay_on_removal() {
+    local krel=$1 res=
+
+    if [[ $INITRD_IN_POSTTRANS ]]; then
+	if [[ -e /run/regenerate-initrd/all ]]; then
+	    res="1"
+	else
+	    local image=$(get_image_name "$krel")
 
-    kernel_changed $krel
+	    if [[ -e /run/regenerate-initrd/$image-$krel ]]; then
+		res="1"
+	    fi
+	fi
+    fi
+    dlog "may_delay_on_removal => \"$res\""
+    echo "$res"
 }
 
 remove_kernel_modules() {
     local krel=$1
-    cat >/dev/null
+
+    sed -rn '/\.ko(|\.xz|\.gz|\.zst)/p' >$tmpdir/kernel-modules
+    sed 's:.*/::' <$tmpdir/kernel-modules >$tmpdir/kernel-basenames
 
     # FIXME: remove KMP symlinks that no longer work
-    kernel_changed $krel
+    kernel_changed "$krel" "" "$(may_delay_on_removal "$krel")" \
+		   <$tmpdir/kernel-basenames
 }
 
 add_kmp() {
@@ -567,15 +661,13 @@ add_kmp() {
         esac
 	dlog "add_kmp: processing $kmp for $krel"
 	[ -d $dir -a -f /boot/System.map-$krel ] || continue
-	if opt_debug=1 has_unresolved_symbols "$krel" "/"; then
-	    echo "Warning: /lib/modules/$krel is inconsistent" >&2
-	    echo "Warning: weak-updates symlinks might not be created" >&2
-	fi
 
 	if kmp_is_present $kmp $krel; then
 	    log "Package $kmp does not need to be added to kernel $krel"
-	    run_depmod_build_initrd "$krel" <$tmpdir/basenames-$kmp || \
-		status=1
+	    run_depmod "$krel" && \
+		build_initrd "$krel" "" "$INITRD_IN_POSTTRANS" \
+			     <$tmpdir/basenames-$kmp || \
+		    status=1
 	    continue
 	fi
 	local old_kmp=$(previous_version_of_kmp $kmp $krel)
@@ -584,15 +676,25 @@ add_kmp() {
 	    add_kmp_modules "$kmp" "$krel"
 	    if [ -z "$old_kmp" ]; then
 		log "Package $kmp added to kernel $krel"
-		run_depmod_build_initrd "$krel" <$tmpdir/basenames-$kmp || \
-		    status=1
+		run_depmod "$krel" $(cat $tmpdir/modules-$kmp) && \
+		    build_initrd "$krel" "" "$INITRD_IN_POSTTRANS" \
+				 <$tmpdir/basenames-$kmp || \
+			status=1
 	    else
 		log "Package $old_kmp replaced by package $kmp in kernel $krel"
-		cat $tmpdir/basenames-{$old_kmp,$kmp} \
-		| run_depmod_build_initrd "$krel" || status=1
+		run_depmod "$krel" $(cat $tmpdir/modules-$kmp) && \
+		    cat $tmpdir/basenames-{$old_kmp,$kmp} \
+			| build_initrd "$krel" "" "$INITRD_IN_POSTTRANS" || \
+			status=1
 	    fi
+	elif [[ $old_kmp ]]; then
+	    log "Package $old_kmp kept in kernel $krel (not replaced by $kmp)"
 	else
-	    dlog "add_kmp: skipped $kmp"
+	    echo "FAILED to add $kmp in kernel $krel" >&2
+	    if [[ $opt_debug -gt 0 ]] && \
+		   has_unresolved_symbols "$krel" "/"; then
+		echo "Warning: /lib/modules/$krel is inconsistent" >&2
+	    fi
 	fi
     done
     dlog "add_kmp: status=$status"
@@ -623,12 +725,7 @@ remove_kmp() {
 	[ -d $dir -a -f /boot/System.map-$krel ] || continue
 	dlog "remove_kmp: processing $kmp for $krel"
 	if kmp_is_present $kmp $krel; then
-	    local other_found=0 inconsistent=0
-
-	    if opt_debug=1 has_unresolved_symbols "$krel" "/" \
-			>$tmpdir/unresolved-"$krel" 2>&1; then
-		inconsistent=1
-	    fi
+	    local other_found=0
 
             if [ $krel != "$(cat $tmpdir/krel-$kmp)" ]; then
                 remove_kmp_modules "$kmp" "$krel"
@@ -647,22 +744,20 @@ remove_kmp() {
 	    done < $tmpdir/kmps
 	    if [ -n "$other_kmp" ]; then
 		log "Package $kmp replaced by package $other_kmp in kernel $krel"
-		cat $tmpdir/basenames-{$kmp,$other_kmp} \
-		| run_depmod_build_initrd "$krel" || status=1
+		run_depmod "$krel" && \
+		    cat $tmpdir/basenames-{$kmp,$other_kmp} \
+			| build_initrd "$krel" "" "$(may_delay_on_removal "$krel")" || \
+			status=1
 	    else
 		log "Package $kmp removed from kernel $krel"
 		if [ $other_found -eq 1 ]; then
 		    log "Weak-updates symlinks to no other $kmpshort package could be created"
-		    if [ $inconsistent -eq 1 ]; then
-			echo "Warning: /lib/modules/$krel was inconsistent before removal of $kmp" >&2
-			[ -s $tmpdir/unresolved-"$krel" ] && \
-			    cat $tmpdir/unresolved-"$krel"
-		    fi
 		fi
-		run_depmod_build_initrd "$krel" <$tmpdir/basenames-$kmp || \
-		    status=1
+		run_depmod "$krel" && \
+		    build_initrd "$krel" "" "$(may_delay_on_removal "$krel")" \
+				 <$tmpdir/basenames-$kmp || \
+			status=1
 	    fi
-	    rm -f $tmpdir/unresolved-"$krel"
 	fi
     done
     dlog "remove_kmp: status=$status"
@@ -717,6 +812,7 @@ usage() {
 
 ##############################################################################
 
+echo "weak-modules2 startup" >&2
 save_argv=("$@")
 options=`getopt -o vh --long add-kernel,remove-kernel,add-kmp,remove-kmp \
                       --long add-kernel-modules,remove-kernel-modules \
@@ -842,4 +938,5 @@ case $mode in
     remove_kmp "$1"
 esac
 
+echo "weak-modules2 finished" >&2
 # vim:shiftwidth=4 softtabstop=4