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Comment by bcantrill | Hacker News Reader

On AMD, DIMM training is done by the PSP. And you have to run the PSP to run the SoC, so we have no alternative there.

More generally, we have implemented and opened everything we can; there still remain opaque bits like the PSP, as well as some smaller bits scattered through the machine (e.g., SSD firmware, MCU boot ROMs, VR firmware, etc.). We have endeavored to make as open a system as possible within the constraint of not making our own silicon. And while we haven't talked about it publicly, we will also open our schematics when we ship the rack, allowing everyone to see every component in the BOM. While we do have some (necessary) proprietary blobs in the system, we want to at least be transparant about where they are!

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What's the "VR" in "VR firmware" stand for? Unless Oxide has invented a revolutionary VR-based user interface for server hardware, I expect I misread that line. ;)

Probably voltage regulator.

Oh, sorry: "VR" is a "voltage regulator" in this context. You can see our drivers for these parts in Hubris, our all-Rust system that runs on our service processor.[0] All of our drivers are open, but the parts themselves do contain (small) proprietary firmware blobs.

[0] https://github.com/oxidecomputer/hubris

Why not write your own firmware for these? They may be a lot more sophisticated than I am thinking, but voltage regulators usually have a datasheet/manual with a set of control registers, and you likely want to set those registers based on the physical hardware you have.

The regulators are actually quite sophisticated and have many undocumented registers that set how things like the communications with the processor work, nonlinear control algorithms, etc.

Very interesting. I would assume that parameters for the control algorithms are actually a few of the things you want to set for yourself, since that lets you optimize system stability under load switches. Your board might also have more or less inductance or capacitance than other motherboards, and this can affect the stability and performance of the control loop a lot. It's a shame they don't give you the documentation about those control systems to figure out how to set those parameters for yourself.

> the constraint of not making our own silicon

Is changing that on your roadmap?

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