Making changes to the device tree

[Aditya Badole]

Hi all!
I wanted to make some changes to the device tree, specifically the memory nodes. I tried hacking something together in generators/rocket-chip/src/main/scala/diplomacy/DeviceTree.scala, but I'm not sure if that's the way to go. I'm building the AFI for the CVA6 config. Appreciate any advice.

Thanks in advance!

[Jerry Zhao]

Can you describe in more detail what you are trying to alter?

-Jerry

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[Aditya Badole]

Hi Jerry,
Essentially I want some section of the main memory to not be visible to the OS. Specifically, I want to reserve a block of about 256MB at the end of the physical region.

[Jerry Zhao]

IMO it is easier to hack around in SW to achieve this goal, than to mess around with the in-ROM-DTB.

I would do this by modifying the generated DTS by hand to excise the last 256 MB. Then configure OpenSBI to pass my modified DTS to the kernel, instead of the one baked into the ROM. 

-Jerry

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