In 78599c32ef, CFI endproc decoration was
added to locore64.S. However, it missed the subtle detail that
__restartkernel_virtual() falls through to __restartkernel(). This was
causing boot failure on PowerMac G5, as it tried to execute the
epilogue as code.
Fix this by branching to __restartkernel() instead of intentionally
running off the end of the function.
While here, add some additional notes on how the virtual mode restart
works.
MFC after: 3 days
d26f2a50ff