From NetBSD:

From NetBSD:
Add a check in the kernel reload device (/dev/reload) to protect
against the MMU switch code being in different locations between
the running kernel and the new kernel.  Returns ENODEV if the reload
fails.
Change the error return from EFAULT to ENOEXEC when kernel_reload
gets a short write on the exec header.
Missed a prototype for kernel_reload().