I wrote in 2024 a blog post about how cheap and low powered Chromebook was one of my favorite devices to use day to day. At the time I was praising how well ChromeOS worked, especially thanks Crostini, a full Linux VM that you can run inside ChromeOS.
Two years later, things changed. I still have the same Chromebook Lenovo Duet
3, and up until now I would sporadically use it. However the experience is
getting worse for each day: I need to constantly resize the disk VM a few
MBs
because otherwise Crostini would fail to start, corrupted characters in the
Terminal app that means I
needed to disable the 2D Canvas Acceleration in chrome:flags.
None of those issues are deal breaker since they both have workarounds, but they're all recent issues. I kind think that this is the result of Android and ChromeOS getting merged. Google seems to be focusing more in getting Android to work well as a desktop OS (and this shows, I have a Pixel 9 Pro and its Linux Terminal VM is getting much better) than to improve ChromeOS. That makes sense, in some ways Android is a much more capable OS than ChromeOS, but on the other hand it is sad to see ChromeOS to wither in real time.
Since I was kind frustrated with ChromeOS, I decided to take a look at something that I knew supported my Lenovo Duet 3 for some time: postmarketOS. For those who don't know, postmarketOS is an Alpine Linux based-distro focused in replacing the original OS from old phones (generally running Android) with a "true" Linux distro. They also seem to support some Chromebooks because of their unique architecture and luckily they support my device under the google-trogdor platform.
I will not go too deep in the install instructions, I recommend following the
official
instructions
plus this blog post for Duet
3 itself.
I did go a step further and replaced the pmbootstrap install command with:
$ pmbootstrap install --disk=/dev/mmcblk1 --fde --filesystem=btrfs
The --fde flag enables Full Disk Encryption that I think it is a must have
for a portable device. Keep in mind that this will ask the password at every
boot and the password screen will always show in vertical instead of horizontal
orientation, one of the quirks of using a LCD panel for tablets instead of one
for laptops.
The --filesystem=btrfs uses the (in)famous
btrfs filesystem instead of the default
ext4. I don't have strong opinions either in favor or against btrfs, but since
this is a more traditional distro (e.g., it is not an immutable distro like
NixOS), I think that having support for snapshots is a must. This
--filesystem=btrfs sets a pretty good subvolume layout too:
# sudo btrfs subvolume list /
ID 256 gen 321 top level 5 path @
ID 257 gen 341 top level 5 path @home
ID 258 gen 298 top level 5 path @root
ID 259 gen 111 top level 5 path @snapshots
ID 260 gen 13 top level 5 path @srv
ID 261 gen 9 top level 5 path @tmp
ID 262 gen 341 top level 5 path @var
ID 263 gen 13 top level 262 path @var/lib/portables
ID 264 gen 167 top level 262 path @var/lib/machines
# mount | grep btrfs
/dev/mapper/root on / type btrfs (rw,relatime,compress=zstd:2,ssd,space_cache=v2,subvolid=256,subvol=/@)
/dev/mapper/root on /.snapshots type btrfs (rw,relatime,compress=zstd:2,ssd,space_cache=v2,subvolid=259,subvol=/@snapshots)
/dev/mapper/root on /root type btrfs (rw,relatime,compress=zstd:2,ssd,space_cache=v2,subvolid=258,subvol=/@root)
/dev/mapper/root on /srv type btrfs (rw,relatime,compress=zstd:2,ssd,space_cache=v2,subvolid=260,subvol=/@srv)
/dev/mapper/root on /var type btrfs (rw,relatime,compress=zstd:2,ssd,space_cache=v2,subvolid=262,subvol=/@var)
/dev/mapper/root on /home type btrfs (rw,relatime,compress=zstd:2,ssd,space_cache=v2,subvolid=257,subvol=/@home)
To be clear, this @snapshots subvol is not used by anything by default. I am
using it with btrbk to get daily backups
though:
$ cat /etc/btrbk/btrbk.conf
compat busybox
timestamp_format long
snapshot_preserve_min 2d
snapshot_preserve 7d
volume /
snapshot_dir /.snapshots
subvolume .
$ systemctl cat btrbk.timer
# /etc/systemd/system/btrbk.timer
[Unit]
Description=Run btrbk daily
[Timer]
OnCalendar=daily
Persistent=true
RandomizedDelaySec=30min
[Install]
WantedBy=timers.target
$ systemctl cat btrbk.service
# /etc/systemd/system/btrbk.service
[Unit]
Description=btrbk Btrfs snapshots
Documentation=man:btrbk(1) man:btrbk.conf(5)
ConditionPathExists=/etc/btrbk/btrbk.conf
[Service]
Type=oneshot
ExecStart=/usr/bin/btrbk run
If you're coming from Alpine the commands above seems suspicious. Why systemd? Well, postmarketOS supports systemd, mostly because of KDE and GNOME, and I since I am using the later and prefer systemd anyway, this was more of a blessing than a curse to me. Having systemd installed by default also made installing Nix a breeze in postmarketOS, I just needed to do:
# doas-sudo-shim is missing some flags that are needed for the nix-installer,
# so we need to replace it with proper sudo
$ doas apk add curl sudo !doas !doas-sudo-shim
# The new experimental Nix installer: https://github.com/NixOS/nix-installer/
$ curl -sSfL https://artifacts.nixos.org/nix-installer | sh -s -- install --enable-flakes
And yes, I decided to use GNOME because I think this form factor (a hybrid laptop/tablet) works perfectly with it. I always thought that GNOME was a well polished interface but it is kind limiting for a desktop environment (this is why I particularly prefer KDE for desktops). But this device is not a desktop and GNOME fits like a glove.
Do I recommend postmarketOS for this device? It depends on your needs. I recommend reading the Wiki entry for the device first. For example, the pen is not working for me (but it seems there is a workaround), neither docking (if I undock and dock the device again the device stays in portrait). I don't use the pen so the first issue doesn't matter to me, and for the second issue I disabled the rotation sensor like the Wiki says. Also the external display support is wonky enough that I stopped trying to use it for now. Another issue is that this device is working well enough in v25.12 release, but I tried edge once (the rolling release channel) and my touchpad started to work in absolute instead of relative mode. Sadly because I wanted to use edge to get GNOME 50, but I hope those issues get ironed out until the next stable release.
But on the other hand, this is an actual Linux distro. Given the limitations and issues, it is working really well. Before trying postmarketOS I thought the only reason ChromeOS worked as well in this device as it did is because Google invested a lot to optimise the OS and browser to run well in low end devices. And while this is probably true, GNOME is also running really well here, and GNOME is considered one of the heaviest desktop environments in Linux. Also I am really happy to use Firefox as my browser instead of Chrome, since I used Firefox everywhere else except in ChromeOS. I was worried that Firefox would run too slow here since I tried it once via Crostini, but running it natively in postmarketOS feels relatively snappy (considering the hardware constraints).
While Crostini was really good, there was still some overhead of running a Linux VM in a already constrained device. For example, cloning nixpkgs in this device took "only" ~15 minutes, while it took more than half an hour to clone in ChromeOS.
So for me, postmarketOS is a revelation. It kind remembers me at the time when I installed Arch Linux in my Netbook and making it usable again after fighting a Windows installation. It is making this device usable again for my needs, and I can say that the Duet 3 is back to becoming my favorite device again, just this time without ChromeOS.