GFFB_CRTC0
pcrt = GFFB_READ_4(GFFB_CRTC0 + 0x081C) & 0xFFFFFFFC;
GFFB_WRITE_4(GFFB_CRTC0 + 0x081C, pcrt);
GFFB_READ_4(GFFB_CRTC0 + GFFB_DISPLAYSTART),
GFFB_WRITE_4(GFFB_CRTC0 + GFFB_DISPLAYSTART, sc->sc_fboffset);