I had, until recently, a problem when it came to test memory on the nodes in my lab. Until now, I was able to PXE boot memtest+, but had to go down to the lab and plug a screen to check the output. Multiple annoyances: first I had to move my ass to the lab room, then I add to do some difficult things to plug a screen to the node, then I had to come back from time to time and look at the output. All of these right in front of the cooling units, which blow some really cold air now that they work correctly.
This morning I investigated in the source code of memtest+ and found out it supports output to serial consoles since recently!
A little upgrade later, I can now boot memtest+ with the console=ttyS0,57600 command line parameter and just watch my serial line output, without moving at all! Yay!
DEFAULT memtest console=ttyS0,57600 LABEL memtest KERNEL images/tools/memtest
(Btw for those who’ll find funny to use DEFAULT memtest… PXE boot choices are updated via a cgi script called from an intranet tool, which itself is wrapped in a little GTK systray applet. This applet allows to reboot, shut down, power on, reinstall various distributions, follow serial line, open an ssh connection, on the lab’s nodes. This tool is also useable via command line for scripting power).