The article argues that RISC‑V’s design creates inefficiencies and fragmentation, especially for low‑cost microcontrollers and high‑performance cores.

RISC‑V is an open instruction set architecture developed by an industry consortium. It is offered without licensing fees and is intended for a range of applications from tiny embedded cores to larger processors.

According to the author, interrupt handling in a base RISC‑V implementation requires at least 44 cycles to save registers and invoke a handler, compared with 27 cycles for a Cortex‑M0 core, which pushes all required registers in hardware. The additional cycles arise from the need to use optional extensions such as Zicsr for interrupt support.

The article also notes that array access, a common operation, is inefficient because the base ISA lacks a register‑plus‑scaled addressing mode; a proposed Zba extension adds two instructions but still results in longer code sequences.

The encoding scheme scatters immediate fields across instruction bits, making decoding complex. Compressed 16‑bit instructions introduce multiple formats that vary by extension, leading to inconsistent interpretations of the same bit pattern.

Optional features such as multiplication, division, CSRs, and a system timer are not required by the base specification, forcing implementers to add proprietary extensions to achieve functionality. This optionality creates incompatible hardware groups and complicates software development, as programs must detect which extensions are present before using specific instructions.

While the low cost of RISC‑V makes it attractive for simple embedded devices, the article suggests that the cumulative effect of high interrupt latency, limited addressing options, and extensive optional extensions may hinder its adoption in performance‑critical markets.