diff -ur grub-2.04.orig/util/grub-mkconfig.in grub-2.04/util/grub-mkconfig.in
--- grub-2.04.orig/util/grub-mkconfig.in	2019-08-18 15:43:15.196000000 +0200
+++ grub-2.04/util/grub-mkconfig.in	2019-08-18 15:43:33.498000000 +0200
@@ -133,6 +133,21 @@
 
 # Device containing our userland.  Typically used for root= parameter.
 GRUB_DEVICE="`${grub_probe} --target=device /`"
+
+# Rewrite to sane LVM node (Code from PLD Linux geninitrd):
+# /dev/mapper/sys-rootfs -> /dev/sys/rootfs
+# /dev/mapper/blodnatt-blah--bleh -> /dev/blodnatt/blah-bleh
+# /dev/mapper/vg--meaw-root -> /dev/vg-meaw/root
+case "$GRUB_DEVICE" in
+	/dev/mapper/*-*)
+		LVM2_LV_NAME='' LVM2_VG_NAME=''
+		eval $(lvs --noheadings --nameprefixes "$GRUB_DEVICE" 2>/dev/null)
+		if [ -n "$LVM2_VG_NAME$LVM2_LV_NAME" ]; then
+			GRUB_DEVICE=/dev/$LVM2_VG_NAME/$LVM2_LV_NAME
+		fi
+	;;
+esac
+
 GRUB_DEVICE_UUID="`${grub_probe} --device ${GRUB_DEVICE} --target=fs_uuid 2> /dev/null`" || true
 GRUB_DEVICE_PARTUUID="`${grub_probe} --device ${GRUB_DEVICE} --target=partuuid 2> /dev/null`" || true