[yocto] Password updates to compressed root image in flash
dbilsby at tekmicro.co.uk
Mon Feb 1 03:47:23 PST 2016
We have a project which will use a Xilinx Zynq running embedded Linux
built by Yocto (probably kernel 4.0). The system will boot from QSPI,
this will contain the FSBL, u-boot, compressed kernel and compressed
rootfs. The rootfs will be expanded into an initramfs which will then be
used as the running systems rootfs (rw).
How given this arrangement do you make passwd updates persistent across
reboots as currently the update will only affect the RAM copy of
/etc/passwd and not get written back to the password file stored in the
compressed rootfs image in flash?
Similarly how can things like the public key which DropBear generates at
boot time be stored permanently so it does not get regenerated every time?
This seems like such an obvious question, however I have not found an
answer when searching. I thought it may be possible to split the rootfs
into effectively a read-only part (read-write but non-persistent) and a
read-write part (persistent) and the splice the two together, but I'm
not sure how best to do this. Flash space is very tight on this system
so keeping the rootfs in flash uncompressed is not an option.
Any suggestions as to how this is best handled very much appreciated.
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