Punch list §25 item 4.3.5a complete.
Firmware (EDK2 RISC-V) leaves Sv57 paging active at kernel entry with an
identity mapping that has at least one confirmed hole (PLIC threshold
register). Verified live before acting: satp.MODE/PPN and __kernel_start's
address confirmed identity mapping; switched to Bare mode (csrw satp, x0 +
sfence.vma) in arch_early_init(), ahead of pmm_init()/vmm_init().
Three-arch acceptance boot clean, zero exceptions; riscv64's PLIC_THRESHOLD
write now survives (PLIC driver code itself lands separately with 4.3.5b).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
