The description of the kernelvec‘s  behavior is inaccurate.

book-riscv-rev5.pdf

section 4.5, pdf page 48.

<img width="1028" height="171" alt="Image" src="https://github.com/user-attachments/assets/1e56bb00-40e2-4b92-89e5-17f0cabf5b59" />


The description that all 32 registers are pushed onto the stack is inaccurate. In reality, only caller-saved registers are saved. See the kernelvec function code for details.