Marvels of Memory Auto-configuration (also known as SPD)

System memory configuration is a transparent operation nowadays, something that we all came to expect to just work out of the box. Still, it does happen behind the scenes every single time we boot our computers. This requires the cooperation of hardware components on the mainboard and on memory modules themselves, as well as firmware code to drive these. While it is possible to just let it happen, having a deeper understanding of how it works makes it possible to access valuable information from the operating system at run-time.

I will take you through the history of system memory configuration from the mid 70s to now. We will explore the different types of memory modules, how their configuration data is stored and how the firmware can access them. We will see which problems had to be solved along the way and how they were solved. Lastly we will see how Linux supports reading the memory configuration information and what you can do with that information.