On 2026/03/16 02:13, Jonathan Carter wrote:
Yikes. Ok lets see how much mksquashfs can shave off that with a huge
dictionary and xz compression:
4.4G extracted.squashfs
Woah. That's less than 10% of the total uncompressed data!
I tried to every tip I could find to get that smaller using just
squashfs. The best I could do was score 80MB by running hardlink -cv on
the tree to hardlink files in advance. Everything else just either made
the process slower or the resulting image larger, so I think squashfs
options are about exhausted.
So I thought I'd check what the biggest files are shared across the
media, since there might be some sacrifices that are worth while.
The top one already seems like an easy one!
218526876
extracted/mate-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
218526876
extracted/lxqt-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
218526876
extracted/lxde-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
218526876
extracted/kde-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
218526876
extracted/gnome-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
218526876
extracted/cinnamon-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
218515930
extracted/xfce-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
That's 218MiB for an initrd.img that we don't use. The one we boot for
live is on the USB media filesystem, and on the target system, it's
generated from scratch. Since that is its size already compressed, that
could make a yummy saving by just deleting it as part of the build
process. And this would be beneficial even for our existing images.
The second biggest file is libQt6WebEngineCore.so.6.9.2:
201778840
extracted/xfce-filesystem.squashfs/usr/lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6.9.2
201778840
extracted/mate-filesystem.squashfs/usr/lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6.9.2
201778840
extracted/lxqt-filesystem.squashfs/usr/lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6.9.2
201778840
extracted/lxde-filesystem.squashfs/usr/lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6.9.2
201778840
extracted/kde-filesystem.squashfs/usr/lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6.9.2
201778840
extracted/gnome-filesystem.squashfs/usr/lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6.9.2
201778840
extracted/cinnamon-filesystem.squashfs/usr/lib/x86_64-linux-gnu/libQt6WebEngineCore.so.6.9.2
184513406
extracted/standard-filesystem.squashfs/boot/initrd.img-6.18.12+deb14-amd64
I believe that's only necessary if you display web pages in Calamares,
which we don't do. It might be possible to drop this dependency, or have
a calamares binary with libQt6WebEngineCore support and one without, so
that derivatives who'd like to use that feature still can.
Thunderbird's libxul is next:
176609760 extracted/lxqt-filesystem.squashfs/usr/lib/thunderbird/libxul.so
176609760 extracted/gnome-filesystem.squashfs/usr/lib/thunderbird/libxul.so
176609760
extracted/cinnamon-filesystem.squashfs/usr/lib/thunderbird/libxul.so
I think it's better to just remove thunderbird, it doesn't have that
much use on a live image, and if someone really wants to install it,
then it's easy enough.
Then there's a bunch of stuff we'd want. Firefox's libxul (pity that
Firefox and Thunderbird can't share that), libllvm, libwebkit2gtk and
then another large thunderbird file:
87696513 extracted/lxqt-filesystem.squashfs/usr/share/thunderbird/omni.ja
87696513 extracted/gnome-filesystem.squashfs/usr/share/thunderbird/omni.ja
Then there's some package lists that I was sure was deleted in the past:
58409448
extracted/xfce-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
58409448
extracted/standard-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
58409448
extracted/mate-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
58409448
extracted/lxqt-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
58409448
extracted/lxde-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
58409448
extracted/kde-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
58409448
extracted/gnome-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
58409448
extracted/cinnamon-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_source_Sources
56077914
extracted/xfce-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
56077914
extracted/standard-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
56077914
extracted/mate-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
56077914
extracted/lxqt-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
56077914
extracted/lxde-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
56077914
extracted/kde-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
56077914
extracted/gnome-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
56077914
extracted/cinnamon-filesystem.squashfs/var/lib/apt/lists/deb.debian.org_debian_dists_forky_main_binary-amd64_Packages
That probably compresses very well, but still it's probably best to
delete those after build.
-Jonathan
