[Buildroot] [PATCH v2] Makefile: Update mtime of $(TARGET_DIR)/usr in target-finalize

[Peter Korsgaard <peter@korsgaard.com>]

>>>>> "Chris" == Chris Lesiak <chris.lesiak@licor.com> writes:

 > The systemd ConditionNeedsUpdate option is useful when offline updates
 > of the vendor operating system resources in /usr require updating of
 > /etc or /var on the next following boot.

 > Two examples of services making use of this option are
 > systemd-hwdb-update.service and systemd-sysusers.service.

 > ConditionNeedsUpdate=/etc will be true if the mtime of /etc/.updated
 > is older than the mtime of /usr.  After services conditional on
 > ConditionNeedsUpdate have run, systemd-update-done.service will
 > synch the mtime of /usr to /etc/.updated so that the condition will
 > be false on subsequent boots.

 > For systems with writable /usr partitions where updates are done to
 > the running system, the update program will touch /usr as a final step.
 > But with Buildroot, where updates are often done by dumping a new
 > image onto the device, and where /usr is on a filesystem mounted
 > read-only, touching /usr as part of the update process is not practical.
 > Instead, it should be done a build time.

 > For testers, please note that systemd-update-done in v234 added a
 > regression where the mtime of /etc/.updated is set to the current time
 > instead of the mtime or /usr.  This will be fixed in v239.

 > For more details, see:
 > http://0pointer.de/public/systemd-man/systemd.unit.html
 > http://0pointer.de/public/systemd-man/systemd-update-done.service.html

 > Signed-off-by: Chris Lesiak <chris.lesiak@licor.com>
 > Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
 > ---
 > Changed v1 --> v2
 >   - Provide a more detailed commit message.

Committed to 2018.02.x, thanks.

-- 
Bye, Peter Korsgaard