GUFS_SEL
gdt_segs[GUFS_SEL].ssd_limit = atop(0 - 1);
PCPU_SET(fsgs_gdt, &gdt[GUFS_SEL].sd);
PCPU_SET(fsgs_gdt, &gdt[GUFS_SEL].sd);
PCPU_SET(fsgs_gdt, &gdt[myid * NGDT + GUFS_SEL].sd);
td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);
td->td_frame->tf_fs = GSEL(GUFS_SEL, SEL_UPL);