GPRIV_SEL
static uint32_t _kprivsel = GSEL(GPRIV_SEL, SEL_KPL);
ASSYM(KPSEL, GSEL(GPRIV_SEL, SEL_KPL));
gdt_segs[GPRIV_SEL].ssd_limit = atop(0 - 1);
gdt_segs[GPRIV_SEL].ssd_base = (int)pc;
dblfault_tss->tss_fs = GSEL(GPRIV_SEL, SEL_KPL);
gdt_segs[GPRIV_SEL].ssd_base = (int)pc;