How to enter real mode

[Collins Chen]

Dear Ron,
     I want to back to real mode in crt0.S, following are my codes. But I find
it don't back to real mode, it is still in protected mode. Do you know what is
the matter with the codes? Thanks!

Regards,
Collins

movl %cr0, %eax
andb $0xfe, %al
movl %eax, %cr0
ljmp      $0x8000, $.backreal
backreal: