In order to see the SPD (detailed memory information) data, the user currently has to manually load the needed kernel driver. Which driver to load depends on the memory type. Depending on the driver user, the devices may even have to be instantiated manually and this is a non-trivial multi-step task. Plus you need to be root to do it.

I would like to attempt to automatize all this at least in the most common and simple cases like Intel x86 desktop. The idea would be to figure out the memory type and the I2C address of the SPD EEPROMs based on DMI data. If the DMI data is of good quality then it should be possible to automatically figure out which driver to use and to instantiate the devices at boot time.

If this works then running "decode-dimms" (or any other equivalent tool) should just work after boot without any preparatory work, for all users.

I plan to start implementing this for DDR3 memory and the i2c-i801 SMBus controller driver because that's what I have on my workstation. If it works, doing the same for DDR4 shouldn't be too difficult. Once this works for the i2c-i801, it should be pretty trivial to do the same with other SMBus controller drivers, for example i2c-piix4.

Excluded from the scope are large server systems with multiple SMBus controllers or multiplexed SMBus. Also excluded are OF/DT systems as I would expect SPD EEPROMs to be declared in the device tree so they would already be instantiated without further effort.

Looking for mad skills in:

i2c-tools kernel smbus dmi

This project is part of:

Hack Week 18

Activity

  • 3 months ago: a_faerber liked Out-of-the-box SPD support
  • 3 months ago: jdelvare added keyword "dmi" to Out-of-the-box SPD support
  • 3 months ago: jdelvare added keyword "smbus" to Out-of-the-box SPD support
  • 3 months ago: jdelvare added keyword "kernel" to Out-of-the-box SPD support
  • 3 months ago: jdelvare added keyword "i2c-tools" to Out-of-the-box SPD support
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