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Comment by transpute | Hacker News Reader

In decreasing order of preference:

  OSS TF-A at EL3 + OSS DDR training (RK3399)
  OSS TF-A at EL3 + closed DDR training (RK3588)
  OSS uboot + closed TF-A 
  closed uboot + closed TF-A

Those who need the features of RK3588 can compare it to competitors which are less open.

Those who don't need the features of RK3588 can use the older and fully open RK3399.

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> OSS TF-A at EL3 + closed DDR training (RK3588)

That should be "blob which does stuff, including DDR training, at EL3".

That blob certainly does DDR training. Maybe it does other stuff. But all of it is done at EL3.

> In decreasing order of preference

"Warning! Diagram is not drawn to scale."

> That blob certainly does DDR training. Maybe it does other stuff. But all of it is done at EL3.

If someone wants to find out, they can load it in IDA/Ghidra?

If it was that easy we'd have a cleanroom FOSS implementation by now. It's been more than two years!

https://wiki.raptorcs.com/wiki/Project_Ortega

Cleanroom reverse engineering for the purpose of publishing new driver code, to avoid legal/IP minefields, is super-expensive. It should be a much narrower scope to determine whether a binary blob's actions are limited to memory training, since there is no requirement to publish reusable source code.

Looks like Collabora is already monitoring the blob, so it's not entirely a mystery:

  At the moment of writing this article, we have identified a few differences from the binary blob previously used, which we can highlight as following:

  Binary BL31 contains some unknown code to get HDMI-RX PHY access working.
  The cpufreq support in binary BL31 is different from TF-A. 

  There could be more issues that are unknown at the moment and users should be aware of it.

> Cleanroom reverse engineering for the purpose of publishing new driver code, to avoid legal/IP minefields, is super-expensive

Project Ortega did it to an entire gigabit ethernet controller for the princely sum of zero dollars:

https://media.ccc.de/v/37c3-11781-adventures_in_reverse_engi...

https://wiki.raptorcs.com/wiki/Project_Ortega

> Binary BL31 contains some unknown code to get HDMI-RX PHY access working.

That doesn't sound like DDR training to me. Maybe now you see the problem?

> That doesn't sound like DDR training to me. Maybe now you see the problem?

It is absolutely a problem, but it's bounded by the ability to inspect and question code/behavior outside the officially claimed rationale. We can prefer open systems and also shine a bright light on the behavior of closed systems.

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