PCI_CB_MEMLIMIT0
sc->sc_memlimit[0] = pci_conf_read(pc, tag, PCI_CB_MEMLIMIT0);
pci_conf_write(pc, tag, PCI_CB_MEMLIMIT0, sc->sc_memlimit[0]);
pci_conf_write(pc, tag, PCI_CB_MEMLIMIT0, 0);