kbuild: do not try to build content of initramfs

When a file supplied via CONFIG_INITRAMFS pointed to a file
for which kbuild had a rule to compile it (foo.c => foo.o)
then kbuild would compile the file before adding the
file to the initramfs.

Teach make that files included in initramfs shall not be updated by adding
an 'empty command'. (See "Using Empty Commands" in info make).

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

diff --git a/usr/Makefile b/usr/Makefile
index e93824269da2aeebdd99c41aebda07a0eb0e5993..5b31c0b61c76a908a42f3b42b8868f3a4de06536 100644 (file)
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -35,6 +35,9 @@ quiet_cmd_initfs = GEN     $@
       cmd_initfs = $(initramfs) -o $@ $(ramfs-args) $(ramfs-input)
 
 targets := initramfs_data.cpio.gz
+# do not try to update files included in initramfs
+$(deps_initramfs): ;
+
 $(deps_initramfs): klibcdirs
 # We rebuild initramfs_data.cpio.gz if:
 # 1) Any included file is newer then initramfs_data.cpio.gz