What's the value of %cs before jump in pm32 on booting?

[jiangtao.jit]

Hi all:

on booting of x86
top of file arch/x86/boot/pmjump.S
there is code
-------------------
GLOBAL(protected_mode_jump)
	movl	%edx, %esi
	xorl	%ebx, %ebx
	movw	%cs, %bx
	shll	$4, %ebx
	addl	%ebx, 2f
...
-------------------

what's the value of %cs here? how was it loaded?
i would really appreciate if someone provide me some references
thank you very much


2011-08-11 
jiangtao.jit