Index: sys/dev/pci/pci.c
===================================================================
--- sys/dev/pci/pci.c
+++ sys/dev/pci/pci.c
@@ -2900,6 +2900,14 @@
 {
 	struct pci_devinfo *dinfo;
 	int ln2range;
+	pci_addr_t map;
+	uint16_t cmd;
+
+	/* Clear the MEMEN or PORTEN bit */
+	map = pm->pm_value;
+	cmd = pci_read_config(dev, PCIR_COMMAND, 2);
+	pci_write_config(dev, PCIR_COMMAND,
+	    cmd & ~(PCI_BAR_MEM(map) ? PCIM_CMD_MEMEN : PCIM_CMD_PORTEN), 2);
 
 	/* The device ROM BAR is always a 32-bit memory BAR. */
 	dinfo = device_get_ivars(dev);
@@ -2914,6 +2922,9 @@
 	if (ln2range == 64)
 		pm->pm_value |= (pci_addr_t)pci_read_config(dev,
 		    pm->pm_reg + 4, 4) << 32;
+
+	/* Restore the original value of PCIR_COMMAND */
+	pci_write_config(dev, PCIR_COMMAND, cmd, 2);
 }
 
 struct pci_map *