[PATCH 21.02 03/11] ramips: mt7621: Add support for ZyXEL NR7101

Bjørn Mork bjorn at mork.no
Tue Jun 8 04:10:55 PDT 2021

Tested-by: Bjørn Mork <bjorn at mork.no>

Unrelated, but confused the hell out of me:

I tested this by sysupgrading from a master based installation using a
5.10 kernel.  And ended up with a tmpfs overlay because of:

[    9.833676] UBIFS (ubi0:1): Mounting in unauthenticated mode
[    9.845003] UBIFS error (ubi0:1 pid 561): ubifs_mount: 'compressor "zstd" is not compiled in
[    9.862780] mount_root: failed to mount -t ubifs /dev/ubi0_1 /tmp/overlay: No error information
[    9.880490] mount_root: overlay filesystem has not been fully initialized yet
[    9.895085] mount_root: switching to ubifs overlay
[    9.904741] mount_root: switching to ubifs failed - fallback to ramoverlay

So I reinstalled the 21.02 build by sysupgrading from the running 21.02,
and everything was fine again - as expected.

I realize that I did this to myself, and that this sort of downgrade
using sysupgrade is a pretty weird usecase.  But maybe there are other
similar situations where we can end up with an unmountable UBIFS due to
the missing compressor?

The problem seems to be as simple as CONFIG_UBIFS_FS_ZSTD being
undefined in target/linux/generic/config-5.4 in 21.02.  It is defined
for a number of targets, though. Just not ralink.

This was fixed in master by commit

  be7b56027899 ("kernel: enable lzo, zlib and zstd in ubifs").

Obvious candidate for backport to 21.02?


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