KDS_SEL
CTASSERT(KDS_SEL == KCS_SEL + 8);
CTASSERT(KDS_SEL == KCS_SEL + 8);
vgc->user_regs.ds = KDS_SEL;
vgc->user_regs.es = KDS_SEL;
vgc->user_regs.ss = KDS_SEL;
vgc->kernel_ss = KDS_SEL;
movw $KDS_SEL, %cx; \
load_segment_registers((KCS_SEL | SEL_KPL), KFS_SEL, KGS_SEL, KDS_SEL);
load_segment_registers(KCS_SEL, KFS_SEL, KGS_SEL, KDS_SEL);
xen_stack_switch(KDS_SEL,
__set_ds(KDS_SEL);