Conversation
conor

Conor Dooley

Edited 1 year ago
Today's interesting discovery is that the c908 on the k230 (despite not really advertising it) supports Zicbom and the T-Head custom CMO stuff.

Apparently the Chinese documentation says it supports it but the English documentation just says "RISC-V Base Cache Management Operation ISA Extensions Version 1.0-rc2-2c97b28, 2021-11-05: Frozen.". In comparison, about a third of the user manual talks about the T-Head CMOs.

edit: I realise it is expected that the document would cover the custom stuff in far more detail, but for the other standard extensions it claims to support, it at least mentions that it supports the instruction and what it does.

https://occ-intl-prod.oss-ap-southeast-1.aliyuncs.com/resource//1699268369347/XuanTie-C908-UserManual.pdf

Made for an interesting conversation on IRC with dramforever, revy and cyy this afternoon :)
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CyReVolt@mastodon.social

Daniel aka CyReVolt 🐢

Reply to @conor

@conor
Do you have a copy of the C908 manual? It is no longer accessible.
I have registered an account on the international XuanTie website to get a manual, no idea if it is the same thing; it is 4.9 MB, sha256 2a3085f920fa4120b9de0a7bfbe253c0c01736bc3fe07ec26f5759e74c43adf7 XuanTie-C908-UserManual_xrvm_20240530.pdf.

I have been poking at the K230 quite a bit now and having an issue reading the time CSR, always getting `0`. Same with the MMIO mtime high/low registers. Do you have an idea? 🥺

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conor

Conor Dooley

Reply to @CyReVolt@mastodon.social
@CyReVolt Unfortunately, I don't seem to have downloaded that document, sorry.
I don't think I've really done anything with my k230 board since about the time of that post, so I have no real memory of anything to do with it, let alone details of CSRs :/
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CyReVolt@mastodon.social

Daniel aka CyReVolt 🐢

Reply to @conor

@conor Alright, no worries, thank you for the reply! =)

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