search for: unload_prep

In pxelinux.asm the xchg instruction in xchg ax,ax . data_on_top: should be xchg ax,dx, I think At the end of pxe_get_cached_info routine,there is and ax,ax jnz .err It is supposed to test for AX status, but since pxenv does pushad and popad, AX doesn't contain status. In fact the other routines calling pxenv don't have this bug.