tree a30a66eaa6fb8f91cbd4a1252715f2399b0f5029
parent fa53cc8dac4eae2d9c595aa33520d448dbec2b3f
author Jan Kundrát <jan.kundrat@cesnet.cz> 1516038514 +0100
committer Jan Kundrát <jan.kundrat@cesnet.cz> 1516039088 +0100

clearfog: Prepare data for flashing via USB to eMMC

At first, I tried to use just one `genimage` configuration file for this
purpose, but I wasn't able to come up with any method to either leverage
the sparseness of the sdcard.img file, or to make `genimage` compress
it. It would be quite wasteful to create huge image files, after all.
However, I wasn't able to find any proper way for doing that just with
`genimage`. I tried:

- The `tar` and `cpio` backends which implement compression. This didn't
work because it seems that one cannot redefine their actual *content*.
- Using `exec_pre` and `exec_post` to force a command. That didn't work
either because genimage checks for file availability prior to running
them.

In the end, this extra shell script simply compresses the SD card image
and calls `genimage` once more. I chose `mksquashfs` because it was much
faster with sparse input than both `gzip` and `bzip2`.

Change-Id: Ia80443108e879fe89b0815e45e5338c5eebf33f3