https://github.com/riscv/riscv-isa-manual/commit/f2ed45b1791bb602657adc2ea9ab5fc409c62542

https://github.com/riscv/riscv-isa-manual/issues/10

f81b722b is a regression.  If a
read-only segment does not begin on a page boundary, it would cause
the ELF loader to blow up.

* Before waiting for IPI by executing wfi instruction, MSIE bit
  should be set in mie CSR for other harts, else they will get
  stuck at the wfi instruction.