On 21/05/13 18:34, Michael Heimpold wrote:
Hi Wolfgang Denx,
Closing a file descriptor does not guarantee that the data has been successfully saved to disk, as the kernel might defer the write.
What is the exact problem you are trying to fix?
I mean, when exactly does adding the sync play a role?
I'm using fw_setenv during system update process. The sequence of such a shell script is something like (much simplified):
... fw_setenv state=2 dd if=... of=/dev/mmcblk0... fw_setenv state=1 ... reboot
Not sure what final "OS" environment you're running, but I would think that "reboot" would sync for you ?
For instance, under BusyBox, we have:-
# reboot --help BusyBox v1.14.0 (2012-02-15 10:28:26 GMT) multi-call binary
Usage: reboot [-d delay] [-n] [-f]
Reboot the system
Options: -d Delay interval for rebooting -n No call to sync() -f Force reboot (don't go through init)
... and under Ubuntu, we have ...
$ reboot --help Usage: reboot [OPTION]... Reboot the system.
Options: -n, --no-sync don't sync before reboot or halt ...
So by default, reboot would (should ?) call sync automatically.
This might point to some other issue ?
Mark J.