udev-cache: take a read-only rootfs into consideration
v2 cover udev-cache: take a read-only rootfs into consideration
From: Chen Qi <[email protected]>
The following changes since commit 042203531b10b37ac9a8201b376f5dec403e51d8:
sanity.bbclass: Fix COREBASE sanity tests (2013-06-27 12:48:56 +0100)
are available in the git repository at:
git://git.pokylinux.org/poky-contrib ChenQi/udev-cache-readonly
http://git.pokylinux.org/cgit.cgi/poky-contrib/log/?h=ChenQi/udev-cache-readonly
Chen Qi (1):
udev-cache: take a read-only rootfs into consideration
meta/recipes-core/udev/udev/init | 54 +++++++++++++++++++------------- meta/recipes-core/udev/udev/udev-cache | 6 ++++ 2 files changed, 38 insertions(+), 22 deletions(-)
Signature · 1 line
1.7.9.5
PATCH v2 1/1 udev-cache: take a read-only rootfs into consideration
From: Chen Qi <[email protected]>
In case of a read-only rootfs, we skip the process of generating udev cache, as the data cannot be persisted between reboots.
However, it's possbile that the $DEVCACHE (default to /etc/dev.tar) exists in a read-only rootfs, no matter how it's generated or installed. In such situation, we try to use $DEVCACHE if possible.
Besides the basic changes in the logic of udev cache handling, this patch also adds code to output more information if the udev cache is not used and VERBOSE enabled.
This patch also changes the readfile function to readfiles function so that it could handle more than one file at once.
--- meta/recipes-core/udev/udev/init | 54 +++++++++++++++++++------------- meta/recipes-core/udev/udev/udev-cache | 6 ++++ 2 files changed, 38 insertions(+), 22 deletions(-)
meta/recipes-core/udev/udev/init +32 -22
@@ -18,15 +18,17 @@ export TZ=/etc/localtime [ -x @UDEVD@ ] || exit 1 [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache [ -f /etc/udev/udev.conf ] && . /etc/udev/udev.conf +[ -f /etc/default/rcS ] && . /etc/default/rcS -readfile () { - filename=$1 +readfiles () { READDATA="" - if [ -r $filename ]; then - while read line; do - READDATA="$READDATA$line" - done < $filename - fi + for filename in $@; do + if [ -r $filename ]; then + while read line; do + READDATA="$READDATA$line" + done < $filename + fi + done } case "$1" in
@@ -52,29 +54,37 @@ case "$1" in mount -a -t tmpfs 2>/dev/null mkdir -p /var/volatile/tmp - # cache handling + # Cache handling. + # A list of files which are used as a criteria to judge whether the udev cache could be reused. + CMP_FILE_LIST="/proc/version /proc/cmdline /proc/devices /proc/atags" if [ "$DEVCACHE" != "" ]; then - readfile /proc/version - VERSION="$READDATA" - readfile /proc/cmdline - CMDLINE="$READDATA" - readfile /proc/devices - DEVICES="$READDATA" - readfile /proc/atags - ATAGS="$READDATA" - if [ -e $DEVCACHE ]; then - readfile /etc/udev/cache.data - if [ "$READDATA" = "$VERSION$CMDLINE$DEVICES$ATAGS" ]; then + readfiles $CMP_FILE_LIST + NEWDATA="$READDATA" + readfiles /etc/udev/cache.data + OLDDATA="$READDATA" + if [ "$OLDDATA" = "$NEWDATA" ]; then (cd /; tar xf $DEVCACHE > /dev/null 2>&1) not_first_boot=1 [ "$VERBOSE" != "no" ] && echo "udev: using cache file $DEVCACHE" [ -e /dev/shm/udev.cache ] && rm -f /dev/shm/udev.cache else - echo "$VERSION$CMDLINE$DEVICES$ATAGS" > /dev/shm/udev.cache + # Output detailed reason why the cached /dev is not used + if [ "$VERBOSE" != "no" ]; then + echo "udev: udev cache not used" + echo "udev: we use $CMP_FILE_LIST as criteria to judge whether the cache /dev could be resued" + echo "udev: olddata: $OLDDATA" + echo "udev: newdata: $NEWDATA" + fi + echo "$NEWDATA" > /dev/shm/udev.cache fi - else - echo "$VERSION$CMDLINE$DEVICES$ATAGS" > /dev/shm/udev.cache + else + if [ "$ROOTFS_READ_ONLY" != "yes" ]; then + # If rootfs is not read-only, it's possible that a new udev cache would be generated; + # otherwise, we do not bother to read files. + readfiles $CMP_FILE_LIST + echo "$READDATA" > /dev/shm/udev.cache + fi fi fi
meta/recipes-core/udev/udev/udev-cache +6 -0
@@ -15,8 +15,14 @@ export TZ=/etc/localtime [ -x @UDEVD@ ] || exit 1 [ -d /sys/class ] || exit 1 +[ -f /etc/default/rcS ] && . /etc/default/rcS [ -f /etc/default/udev-cache ] && . /etc/default/udev-cache +if [ "$ROOTFS_READ_ONLY" = "yes" ]; then + [ "$VERBOSE" != "no" ] && echo "udev-cache: read-only rootfs, skip generating udev-cache" + exit 0 +fi + if [ "$DEVCACHE" != "" -a -e /dev/shm/udev.cache ]; then echo "Populating dev cache" (cd /; tar cf "$DEVCACHE" dev)
Signature · 1 line
1.7.9.5