PCI_MSI_MASK64
mask = pci_conf_read(pc, tag, off + PCI_MSI_MASK64);
pci_conf_write(pc, tag, off + PCI_MSI_MASK64,
mask = pci_conf_read(pc, tag, off + PCI_MSI_MASK64);
pci_conf_write(pc, tag, off + PCI_MSI_MASK64,