NV_CIO_CRE_4B
regp->CRTC[NV_CIO_CRE_4B] = savep->CRTC[NV_CIO_CRE_4B] | 0x80;
rd_cio_state(dev, head, regp, NV_CIO_CRE_4B);
wr_cio_state(dev, head, regp, NV_CIO_CRE_4B);
bios->is_mobile = NVReadVgaCrtc(dev, 0, NV_CIO_CRE_4B) & 0x40;