Hi, On 03/10/2014 02:33, Jinqiang Zeng wrote: > 2014-10-02 10:01 GMT-07:00 Clemens Gruber <clemens.gruber@xxxxxxxxxxxx>: >> Hi, >> >> I am just trying to solve a similar problem as Luca described. I have a >> TQMa28 board running Linux 3.17-rc7 though. >> The capacitors keep the system up for about 1500 more milliseconds after >> the power fails. A GPIO line is set to high as soon as the main power is >> lost. >> >> So I have not much time to quit an important user space process and to >> clean up the ext4 root filesystem before the power fails. >> >> At the moment I pass rootflags=data=journal,commit=1 in the kernel >> commandline to lower the risk of data loss. >> In the user space application I open important files using the O_SYNC flag. >> >> Is there something else I should do to avoid data loss? >> >> How would you implement the "emergency cleanup on power-failure" logic? >> Dedicated driver (similar to the mentioned gpio-event driver?), >> implement it with UIO, let a userspace application running as root >> select /dev/uioX and cleaning up? > how about using netlink to notify the usersapce app on gpio interrupt . thanks to all for your replies. Anyway, I solved the issue simply using the GPIO driver (no kernel modifications needed): - export GPIO number (es 7): $ echo 7 > /sys/class/gpio/export - set direction: $ echo "in" > /sys/class/gpio/gpio7/direction - set event that triggers interrupt: $ echo "falling" > /sys/class/gpio/gpio7/edge Then I create a user space application that executes a poll system call on "/sys/class/gpio/gpio7/value". Regards --- Luca Ellero http://http://www.brickedbrain.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
