kbuild/usr: initramfs list fixed and simplified

Moving logic to scripts/gen_initramfs_list.sh make a nice cleanup in
usr/Makefile.
A new initramfs image will be generated if the initramfs_list file changes.
This patch also fixes the bug with make O=..

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

2 files changed, 62 insertions, 16 deletions

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 3a7663b901f0..6e75ced8b583 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -232,3 +232,30 @@ descend =$(Q)$(MAKE) -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build ob
 # Usage:
 # $(Q)$(MAKE) $(build)=dir
 build := -f $(if $(KBUILD_SRC),$(srctree)/)scripts/Makefile.build obj
+
+# filechk is used to check if the content of a generated file is updated.
+# Sample usage:
+# define filechk_sample
+#	echo $KERNELRELEASE
+# endef
+# version.h : Makefile
+#	$(call filechk,sample)
+# The rule defined shall write to stdout the content of the new file.
+# The existing file will be compared with the new one.
+# - If no file exist it is created
+# - If the content differ the new file is used
+# - If they are equal no change, and no timestamp update
+
+define filechk
+	$(Q)set -e;				\
+	echo '  CHK     $@';			\
+	mkdir -p $(dir $@);			\
+	$(filechk_$(1)) $(2) > $@.tmp;		\
+	if [ -r $@ ] && cmp -s $@ $@.tmp; then	\
+		rm -f $@.tmp;			\
+	else					\
+		echo '  UPD     $@';		\
+		mv -f $@.tmp $@;		\
+	fi
+endef
+
diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
index 59b810396c7b..1d415792ac78 100644
--- a/scripts/gen_initramfs_list.sh
+++ b/scripts/gen_initramfs_list.sh
@@ -2,24 +2,25 @@
 # Copyright (C) Martin Schlemmer <azarah@nosferatu.za.org>
 # Released under the terms of the GNU GPL
 #
-# A script to generate newline separated entries (to stdout) from a directory's
-# contents suitable for use as a cpio_list for gen_init_cpio.
+# Generate a newline separated list of entries from the file/directory pointed
+# out by the environment variable: CONFIG_INITRAMFS_SOURCE
 #
-# Arguements: $1 -- the source directory
+# If CONFIG_INITRAMFS_SOURCE is non-existing then generate a small dummy file.
+#
+# The output is suitable for gen_init_cpio as found in usr/Makefile.
 #
 # TODO:  Add support for symlinks, sockets and pipes when gen_init_cpio
 #        supports them.
 
-usage() {
-	echo "Usage: $0 initramfs-source-dir"
-	exit 1
-}
-
-srcdir=$(echo "$1" | sed -e 's://*:/:g')
+simple_initramfs() {
+	cat <<-EOF
+		# This is a very simple initramfs
 
-if [ "$#" -gt 1 -o ! -d "${srcdir}" ]; then
-	usage
-fi
+		dir /dev 0755 0 0
+		nod /dev/console 0600 0 0 c 5 1
+		dir /root 0700 0 0
+	EOF
+}
 
 filetype() {
 	local argv1="$1"
@@ -76,9 +77,27 @@ parse() {
 	return 0
 }
 
-find "${srcdir}" -printf "%p %m %U %G\n" | \
-while read x; do
-	parse ${x}
-done
+if [ -z $1 ]; then
+	simple_initramfs
+elif [ -f $1 ]; then
+	cat $1
+elif [ -d $1 ]; then
+	srcdir=$(echo "$1" | sed -e 's://*:/:g')
+	dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" 2>/dev/null)
+
+	# If $dirlist is only one line, then the directory is empty
+	if [  "$(echo "${dirlist}" | wc -l)" -gt 1 ]; then
+		echo "${dirlist}" | \
+		while read x; do
+			parse ${x}
+		done
+	else
+		# Failsafe in case directory is empty
+		simple_initramfs
+	fi
+else
+	echo "  $0: Cannot open '$1' (CONFIG_INITRAMFS_SOURCE)" >&2
+	exit 1
+fi
 
 exit 0