Proper way to sync an SD card prior to reboot

[Sebastian Huber]

On 2014-06-19 00:25, Jim Panetta wrote:
>
> To prevent any data loss due to non-flushed buffers at a commanded reboot, we
> would like to sync a multi-partition SD card during our reboot procedure.
>
> Is it enough to issue rtems_disk_fd_sync(fd) for each mounted partition?

No, this is the wrong function.  File systems may have stale data in their data 
structures.

For FAT you can use fsync() or fdatasync() on the root directory.  You can also 
unmount the file system, but for this all open nodes must be closed (including 
working directories, etc.).

>
> Or should we be using unlink(path) as Sebastion Huber mentioned in his
> correspondence with Ali Nasir this April?
> (http://article.gmane.org/gmane.os.rtems.user/22186)
>
> Environment RTEMS 4.11, Zynq (ARM Cortex-A9)
>
>    --Jim Panetta
>


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Sebastian Huber, embedded brains GmbH

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