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Kernel 5.15.39 compiled in Easy Bookworm

May 13, 2022 — BarryK

Partly this was to test that the 'devx' SFS works, and it does.

But also, rufwoof recommended that lz4 be enabled for squashfs in the Linux kernel, as this compression format has very fast decompression. rufwoof's post:

The first time that you boot Easy, the QuickSetup window appears. You can also run it anytime via "Setup -> Quicksetup first-run settings" in the menu. In QuickSetup, there is a checkbox labeled "Recompress easy.sfs" -- tick that, and easy.sfs will be changed from xz-compression to gz-compression. This will give faster reading of files from easy.sfs, and you might notice slightly snappier performance on an older computer.

Having enabled lz4 for squashfs, I intend to change QuickSetup so that it changes xz to lz4, thus giving even more snappy performance.

While I was at it, also enabled lz4 compression for the f2fs filesystem. That's important, as planning to investigate moving the working-partition from ext4 to f2fs. The latter is named "Flash Friendly Filesystem" -- three "F" characters, which lead the creator to the "f2fs" acronym. Interesting that he/she didn't go for "fffs"!

There was another post in the forum, by peebee, informing that the developer of aufs has released a new version for the 5.15.36 kernel. As I have compiled the 5.15.39 kernel, I had to update the aufs patch. Forum post:

For the record, here is how I downloaded and created the source tarball of aufs:

# git clone aufs-aufs5-standalone
# cd aufs-aufs5-standalone/
# git branch -a
# git checkout remotes/origin/aufs5.15.36
# cd ..
# mkdir aufs5-5.15.36-20220513
# cp -a aufs-aufs5-standalone/* aufs5-5.15.36-20220513/
# dir2tgz aufs5-5.15.36-20220513/

This tarball was then used in the kernel build source, patches and scripts, uploaded here:

The build script exposed a problem. After completing the compile, "make headers_install" failed. I was surprised that this runs 'rsync', which does not work as a library is missing, 'libxxhash.o.0'.

The way that you can confirm this, is to run this in a terminal:

# ldd /usr/bin/rsync

Then, to find the package that has this missing library file, go to

I ran the package manager and installed the missing package, 'libxxhash0', and did the entire kernel compile again. This time. success.

This leads to an important point: if you have installed Easy Bookworm to a USB stick, and when a new release comes out, the "udpate" icon on the desktop won't work, as it uses rsync. So, install 'libxxhash0' and you will be ready to update.    

Tags: easy