Phoronix reported on Oct. 29, 2026, that Linux 7.4’s RISC-V changes had merged to Git. The main change lets the kernel detect fast misaligned access at runtime and skip software alignment during user-copy operations on compatible cores. This makes the optimized path available to distribution kernels built without NONPORTABLE, as described in Andy Chiu’s patch series.
How runtime detection changes the user-copy path
Linux 7.3 required the optimization to be enabled at compile time. Linux 7.4 instead checks at runtime whether a core supports fast misaligned access. When that condition is met, the kernel can skip software alignment during user-copy.
| Kernel version | How eligibility is determined | Effect on generic kernels |
| Linux 7.3 | The optimization had to be enabled at compile time. | The approach limited use in generic builds intended for mixed RISC-V hardware. |
| Linux 7.4 | The kernel detects fast misaligned access at runtime. | Distribution kernels built without NONPORTABLE can use the optimized path on compatible cores. |
The change makes the optimization usable across more general kernel builds, while keeping the fast path conditional on the capability detected in the processor core.
The patch’s path into Linux 7.4
Andy Chiu of Tenstorrent submitted the two-patch series on Sept. 11, 2026. Paul Walmsley said it was queued for v7.4 on Oct. 6; a Patchwork notification recorded its application to riscv/linux.git for-next by Walmsley. The RISC-V pull summary also lists a self-test for vectorized user-copy.
What the earlier bandwidth figure measures
The up-to-11% bandwidth improvement is not a Linux 7.4 benchmark. Phoronix attributed the figure to Tenstorrent tests of the earlier optimization; the Linux 7.4 change shifts how kernels become eligible to use that path.
