How to get Synit running on an emulated PostmarketOS device

Begin by following the generic PostmarketOS instructions for running using QEMU, reprised here briefly, and then build and install the Synit packages and (optionally) the SqueakPhone user interface.

Build and install qemu-amd64 PostmarketOS

First, run pmbootstrap init (choose qemu, amd64, and a console UI); or, if you’ve done that previously, run pmbootstrap config device qemu-amd64.

Then, run pmbootstrap install to build the rootfs.

Finally, run pmbootstrap qemu --video 720x1440@60 to (create, if none has previously been created, and) start an emulated PostmarketOS device. You’ll run that same command each time you boot up the machine, so create an alias or script for it, if you like.

Set up ssh access to the emulated device

I have the following stanza in my ~/.ssh/config:

Host pm-qemu
    HostName localhost
    Port 2222
    User user
    StrictHostKeyChecking no
    UserKnownHostsFile /dev/null

Log in to the device using a username and password (SSH_AUTH_SOCK= ssh pm-qemu) and set up SSH key access via ~/.ssh/authorized_keys on the device, however you like to do it. I use vouch.id to log into my machines using an SSH certificate, so I do the following:

mkdir -p .local/bin
cd .local/bin
wget https://vouch.id/download/vouch
chmod a+x vouch
sudo apk add python3
echo 'export VOUCH_ID_PRINCIPAL=tonyg@leastfixedpoint.com' >> ~/.profile

Then I log out and back in again to pick up the VOUCH_ID_PRINCIPAL variable, followed by running

vouch server setup --accept-principals tonyg

(Substitute your own preferred certificate principal username, of course.) After this, I can use the vouch.id app to authorize SSH logins.

Allow port forwarding over SSH to the device

Edit /etc/ssh/sshd_config to have AllowTcpForwarding yes. This will let you use e.g. port-forwarded VNC over your SSH connection to the device once you have the user interface set up.

Build and install the Synit packages

Follow the build and installation instructions to check out and build the code.

Once you’ve checked out the synit module and have all the necessary build dependencies installed, change directory to synit/packaging/squid and run start.sh in one terminal window. Leave this open for the remainder of the build process. Open another terminal, go to synit/packaging, and run make keyfile. Then, run make ARCH=x86_64.

Hopefully the build will complete successfully. Once it has done so, change to synit/scripts and run ./upload-bundle.sh pm-qemu. Then log in to the emulated device and run the ./transmogrify.sh script from the /home/user directory. Reboot the device. When it comes back, you will find that it is running Synit (check ps output to see that synit-pid1 is in fact PID 1).

Build and install the user interface packages

To build (and run locally) the SqueakPhone image, ensure your Unix user is in the input group. Follow the instructions in the SqueakPhone README; namely, first install squeaker, check out the squeak-phone repository, and run make images/current inside it.

Then, on the device, create a file /home/user/dpi.override containing just 256. On the host machine, send your image to the device with ./push-image-to-phone.sh pm-qemu. It should automatically start.

Copyright © 2021–2023 Tony Garnock-Jones, CC BY 4.0