Index: sys/compat/linuxkpi/common/include/linux/pci.h
===================================================================
--- sys/compat/linuxkpi/common/include/linux/pci.h
+++ sys/compat/linuxkpi/common/include/linux/pci.h
@@ -311,19 +311,27 @@
 		return (SYS_RES_MEMORY);
 }
 
+struct resource_list_entry *linux_pci_reserve_bar(struct pci_dev *pdev,
+		    struct resource_list *rl, int type, int rid);
+
 static inline struct resource_list_entry *
-linux_pci_get_rle(struct pci_dev *pdev, int type, int rid)
+linux_pci_get_rle(struct pci_dev *pdev, int type, int rid, bool reserve_bar)
 {
 	struct pci_devinfo *dinfo;
 	struct resource_list *rl;
+	struct resource_list_entry *rle;
 
 	dinfo = device_get_ivars(pdev->dev.bsddev);
 	rl = &dinfo->resources;
-	return resource_list_find(rl, type, rid);
+	rle = resource_list_find(rl, type, rid);
+	/* Reserve resources for this BAR if needed. */
+	if (rle == NULL && reserve_bar)
+		rle = linux_pci_reserve_bar(pdev, rl, type, rid);
+	return (rle);
 }
 
 static inline struct resource_list_entry *
-linux_pci_get_bar(struct pci_dev *pdev, int bar)
+linux_pci_get_bar(struct pci_dev *pdev, int bar, bool reserve)
 {
 	int type;
 
@@ -331,7 +339,7 @@
 	if (type < 0)
 		return (NULL);
 	bar = PCIR_BAR(bar);
-	return (linux_pci_get_rle(pdev, type, bar));
+	return (linux_pci_get_rle(pdev, type, bar, reserve));
 }
 
 static inline struct device *
@@ -521,7 +529,7 @@
 	struct pci_devres *dr;
 	struct pci_mmio_region *mmio, *p;
 
-	if ((rle = linux_pci_get_bar(pdev, bar)) == NULL)
+	if ((rle = linux_pci_get_bar(pdev, bar, false)) == NULL)
 		return;
 
 	/*
@@ -779,7 +787,7 @@
 		pci_release_msi(pdev->dev.bsddev);
 		return avail;
 	}
-	rle = linux_pci_get_rle(pdev, SYS_RES_IRQ, 1);
+	rle = linux_pci_get_rle(pdev, SYS_RES_IRQ, 1, false);
 	pdev->dev.irq_start = rle->start;
 	pdev->dev.irq_end = rle->start + avail;
 	for (i = 0; i < nreq; i++)
@@ -832,7 +840,7 @@
 	if ((error = -pci_alloc_msi(pdev->dev.bsddev, &avail)) != 0)
 		return error;
 
-	rle = linux_pci_get_rle(pdev, SYS_RES_IRQ, 1);
+	rle = linux_pci_get_rle(pdev, SYS_RES_IRQ, 1, false);
 	pdev->dev.irq_start = rle->start;
 	pdev->dev.irq_end = rle->start + avail;
 	pdev->irq = rle->start;
Index: sys/compat/linuxkpi/common/src/linux_pci.c
===================================================================
--- sys/compat/linuxkpi/common/src/linux_pci.c
+++ sys/compat/linuxkpi/common/src/linux_pci.c
@@ -368,7 +368,7 @@
 		PCI_GET_ID(parent, dev, PCI_ID_RID, &rid);
 	pdev->devfn = rid;
 	pdev->pdrv = pdrv;
-	rle = linux_pci_get_rle(pdev, SYS_RES_IRQ, 0);
+	rle = linux_pci_get_rle(pdev, SYS_RES_IRQ, 0, false);
 	if (rle != NULL)
 		pdev->dev.irq = rle->start;
 	else
@@ -624,6 +624,25 @@
 	return (_linux_pci_register_driver(pdrv, dc));
 }
 
+struct resource_list_entry *
+linux_pci_reserve_bar(struct pci_dev *pdev, struct resource_list *rl,
+    int type, int rid)
+{
+	device_t dev;
+	struct resource *res;
+
+	KASSERT(type == SYS_RES_IOPORT || type == SYS_RES_MEMORY,
+	    ("trying to reserve non-BAR type %d", type));
+
+	dev = pdev->pdrv != NULL && pdev->pdrv->isdrm ?
+	    device_get_parent(pdev->dev.bsddev) : pdev->dev.bsddev;
+	res = pci_reserve_map(device_get_parent(dev), dev, type, &rid, 0, ~0,
+	    1, 1, 0);
+	if (res == NULL)
+		return (NULL);
+	return (resource_list_find(rl, type, rid));
+}
+
 unsigned long
 pci_resource_start(struct pci_dev *pdev, int bar)
 {
@@ -631,7 +650,7 @@
 	rman_res_t newstart;
 	device_t dev;
 
-	if ((rle = linux_pci_get_bar(pdev, bar)) == NULL)
+	if ((rle = linux_pci_get_bar(pdev, bar, true)) == NULL)
 		return (0);
 	dev = pdev->pdrv != NULL && pdev->pdrv->isdrm ?
 	    device_get_parent(pdev->dev.bsddev) : pdev->dev.bsddev;
@@ -648,7 +667,7 @@
 {
 	struct resource_list_entry *rle;
 
-	if ((rle = linux_pci_get_bar(pdev, bar)) == NULL)
+	if ((rle = linux_pci_get_bar(pdev, bar, true)) == NULL)
 		return (0);
 	return (rle->count);
 }
Index: sys/dev/pci/pci.c
===================================================================
--- sys/dev/pci/pci.c
+++ sys/dev/pci/pci.c
@@ -5365,7 +5365,7 @@
 }
 #endif /* DDB */
 
-static struct resource *
+struct resource *
 pci_reserve_map(device_t dev, device_t child, int type, int *rid,
     rman_res_t start, rman_res_t end, rman_res_t count, u_int num,
     u_int flags)
Index: sys/dev/pci/pci_private.h
===================================================================
--- sys/dev/pci/pci_private.h
+++ sys/dev/pci/pci_private.h
@@ -163,6 +163,10 @@
 struct pci_map *pci_add_bar(device_t dev, int reg, pci_addr_t value,
 		    pci_addr_t size);
 
+struct resource *pci_reserve_map(device_t dev, device_t child, int type,
+		    int *rid, rman_res_t start, rman_res_t end,
+		    rman_res_t count, u_int num, u_int flags);
+
 struct resource *pci_alloc_multi_resource(device_t dev, device_t child,
 		    int type, int *rid, rman_res_t start, rman_res_t end,
 		    rman_res_t count, u_long num, u_int flags);