Buildroot, Systemd, and Getty

• September 18, 2019
• buildroot  
• systemd  
• getty  
• linux  

I just spent a few hours trying to get systemd to spawn a getty on the vt console for a Linux image that I was building with Buildroot. It turns out that it helps to read the right documentation, which in this case was a blog about systemd console handling.

The money quote for me was:

In systemd, two template units are responsible for bringing up a login prompt on text consoles:

getty@.service is responsible for virtual terminal (VT) login prompts, i.e. those on your VGA screen as exposed in /dev/tty1 and similar devices.

serial-getty@.service is responsible for all other terminals, including serial ports such as /dev/ttyS0. It differs in a couple of ways from getty@.service: among other things the $TERM environment variable is set to vt102 (hopefully a good default for most serial terminals) rather than linux (which is the right choice for VTs only), and a special logic that clears the VT scrollback buffer (and only work on VTs) is skipped.

My Buildroot config wired up a serial-getty but not a getty. Once I added the getty@tty1.service, systemd did what I wanted. Next step is to understand how to control this in Buildroot …