CSC -> CMAC consume-arm: a per-power-session resource with no register footprint, below what black-box probing can reach. An independent RK3568 bring-up reaches a matching engaged-but-empty wall; an open-stack RK3588 effort runs multi-op fp16 matmul and LLM prefill through the same driver, cross-confirming five findings. We publish the full ledger, two upstreamable bugs, and the conditions that would reopen it." />

CSC -> CMAC consume-arm: a per-power-session resource with no register footprint, below what black-box probing can reach. An independent RK3568 bring-up reaches a matching engaged-but-empty wall; an open-stack RK3588 effort runs multi-op fp16 matmul and LLM prefill through the same driver, cross-confirming five findings. We publish the full ledger, two upstreamable bugs, and the conditions that would reopen it." />

CSC -> CMAC consume-arm: a per-power-session resource with no register footprint, below what black-box probing can reach. An independent RK3568 bring-up reaches a matching engaged-but-empty wall; an open-stack RK3588 effort runs multi-op fp16 matmul and LLM prefill through the same driver, cross-confirming five findings. We publish the full ledger, two upstreamable bugs, and the conditions that would reopen it." />

Bringing Up the RK3576 NPU on Mainline Linux: A Byte-Exact Single-Task Path and a Falsification-First Negative Result on Chained-Task Compute | Zenodo

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Published July 2026

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Bringing Up the RK3576 NPU on Mainline Linux: A Byte-Exact Single-Task Path and a Falsification-First Negative Result on Chained-Task Compute

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Hu, Jiaxing1

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The Rockchip RK3576 ships a 6 TOPS NPU whose only fully open software stack is the mainline drivers/accel/rocket driver plus the Mesa Teflon delegate, byte-perfect on the sibling RK3588, yet all-zero on the RK3576. Positive: after root-causing an int8 requantization error (rescale multiplier emitted at Q14 where the hardware consumes Q4, a 2^10 over-scale saturating every output), a single int8 convolution is byte-exact against a CPU reference. Negative (the main contribution): any job with more than one task computes exactly one, the first after the NPU power domain resumes; each later task engages its units, DMAs real input, and advances the sequencer, yet its multiply-accumulate never commits (measured for int8; whether fp16 escapes the wall is argued from mechanism, not yet measured). Under a falsification-first rule we drive the chain through three dispatch mechanisms and refute every software-observable cause: dispatch grammar, the full register write set, config geometry, buffer/cache/IOMMU state, clock/power, and firmware. The vendor's closed stack, on the same kernel, chains dozens of tasks per session, matching every write we make. Our best-supported localization is the on-chip CBUF -> CSC -> CMAC consume-arm: a per-power-session resource with no register footprint, below what black-box probing can reach. An independent RK3568 bring-up reaches a matching engaged-but-empty wall; an open-stack RK3588 effort runs multi-op fp16 matmul and LLM prefill through the same driver, cross-confirming five findings. We publish the full ledger, two upstreamable bugs, and the conditions that would reopen it.

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https://github.com/gahingwoo/linux-rk3576-npu

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Keywords

RK3576

NPU

mainline Linux

rocket driver

reverse engineering

int8 quantization

hardware accelerator

falsification

requantization

RKNN

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10.5281/zenodo.21348017

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