udev-cache: fix to use udev-cache correctly

Previouly, the udev-cache has no real effect even if it's installed
into the system. The key problem here is that at first boot, the
/etc/dev.tar is not present, thus resulting /dev/shm/udev.cache not
created on first boot even if udev-cache is enabled.

This patch fixes this problem. The /dev/shm/udev.cache will be created
if necessary, that is, on first boot or when some part of the system is
changed. In the latter case, the udev cache may not be valid.

[YOCTO #4738]

(From OE-Core rev: 84e0ec2e677fb0236a38478372cdd75797cf5a2e)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 1 insertions, 3 deletions

diff --git a/meta/recipes-core/udev/udev/udev-cache b/meta/recipes-core/udev/udev/udev-cache
index 01fec6e96e..8a84fa9dc8 100644
--- a/meta/recipes-core/udev/udev/udev-cache
+++ b/meta/recipes-core/udev/udev/udev-cache
@@ -17,12 +17,10 @@ export TZ=/etc/localtime
 
 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache
 
-if [ "$DEVCACHE" != "" ]; then
+if [ "$DEVCACHE" != "" -a -e /dev/shm/udev.cache ]; then
         echo "Populating dev cache"
         (cd /; tar cf "$DEVCACHE" dev)
         mv /dev/shm/udev.cache /etc/udev/cache.data
-else
-        rm -f /dev/shm/udev.cache
 fi
 
 exit 0