in handling an interrupt, kernel first saves all the register contents , in
the SAVE_ALL macro, in the last part of this macro, it adjusts the
data segment selectors for kernel mode.
in kernel 2.4, the __KERNEL_DS segment is loaded into %ds and %es, at line
98 of: http://lxr.linux.no/#linux-old+v2.4.31/arch/i386/kernel/entry.S
but in kernel 2.6, __USER_DS segment is loaded into %ds and %es, at line
227 of : http://lxr.linux.no/#linux+v2.6.33/arch/x86/kernel/entry_32.S
I understand that on x86,
