[PATCH 00/31] passage: Define a standard for firmware data flow

Mark Kettenis mark.kettenis at xs4all.nl
Mon Nov 1 19:19:05 CET 2021

> From: François Ozog <francois.ozog at linaro.org>
> Date: Mon, 1 Nov 2021 09:53:40 +0100


> We could further leverage Passage to pass Operating Systems parameters that
> could be removed from device tree (migration of /chosen to Passage). Memory
> inventory would still be in DT but allocations for CMA or GPUs would be in
> Passage. This idea is to reach a point where  device tree is a "pristine"
> hardware description.

I wanted to react on something you said in an earlier thread, but this
discussion seems to be appropriate as well:

The notion that device trees only describe the hardware isn't really
correct.  Device trees have always been used to configure firmware
options (through the /options node) and between firmware and the OS
(through the /chosen node) and to describe firmware interfaces
(e.g. OpenFirmware calls, PSCI (on ARM), RTAS (on POWER)).  This was
the case on the original Open Firmware systems, and is still done on
PowerNV systems that use flattened device trees.

I don't see what the benefits are from using Passage instead.  It
would only fragment things even more.

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