diff --git a/hw/xfree86/common/xf86Bus.c b/hw/xfree86/common/xf86Bus.c
index 33a6336aa..8bd29795f 100644
--- a/hw/xfree86/common/xf86Bus.c
+++ b/hw/xfree86/common/xf86Bus.c
@@ -655,3 +655,225 @@ xf86GetEntityPrivate(int entityIndex, int privIndex)
 
     return &(xf86Entities[entityIndex]->entityPrivates[privIndex]);
 }
+
+/*
+ * Check if the slot requested is free.  If it is already in use, return FALSE.
+ */
+
+Bool
+xf86CheckSlot(const void *ptr, BusType type)
+{
+    int i;
+
+#ifdef XSERVER_LIBPCIACCESS
+    const struct pci_device *pci_ptr = (type == BUS_PCI ?
+             (const struct pci_device *)ptr : NULL);
+#endif
+
+#ifdef XSERVER_PLATFORM_BUS
+    const struct xf86_platform_device *plat_ptr = (type == BUS_PLATFORM ?
+             (const struct xf86_platform_device *)ptr : NULL);
+#endif
+
+    GDevPtr fb_ptr = (type == BUS_NONE ?
+             (GDevPtr)ptr : NULL);
+    const char *msPath = NULL;
+    const char *fbPath = NULL;
+
+    if (ptr == NULL) {
+        return FALSE;
+    }
+
+#ifdef XSERVER_PLATFORM_BUS
+    /* XSERVER_PLATFORM_BUS assumes XSERVER_LIBPCIACCESS */
+    if (plat_ptr) {
+        pci_ptr = plat_ptr->pdev;
+        msPath = plat_ptr->attribs->path;
+    }
+#endif
+
+    if (type == BUS_NONE) {
+        if (!strcasecmp(fb_ptr->driver, "modesetting")) {
+   /*
+    * If xf86ClaimFbSlot() is called by modesetting driver,
+    * busID has not been set and the device name was not specified
+    * via "kmsdev" option, the default "/dev/dri/card0" is used.
+    *
+    * We have to check whether a platform device has previously
+    * grabbed the device we are going to claim.
+    */
+            msPath = xf86FindOptionValue(fb_ptr->options, "kmsdev");
+            if (msPath == NULL) {
+                /* Autoconfigured */
+                msPath = "/dev/dri/card0";
+            }
+        }
+        else
+        if (!strcasecmp(fb_ptr->driver, "fbdev")) {
+   /*
+    * fbdev driver can also call xf86ClaimFbSlot() for
+    * an autoconfigured device, or the device name can be set
+    * via "fbdev" option.
+    */
+            fbPath = xf86FindOptionValue(fb_ptr->options, "fbdev");
+            if (fbPath == NULL) {
+                /* Autoconfigured */
+                fbPath = "";
+            }
+        }
+    }
+
+   /*
+    * Having prepared all data about a candidate, we walk
+    * through all previous entities to check for a collision.
+    */
+
+    for (i = 0; i < xf86NumEntities; i++) {
+        const EntityPtr pent = xf86Entities[i];
+#ifdef XSERVER_LIBPCIACCESS
+        struct pci_device *pci_other;
+#endif
+        const char *msOther = NULL;
+        const char *fbOther = NULL;
+
+        if (pent->numInstances <= 0) {
+        /* All devices are unclaimed, ignore this entity */
+            continue;
+        }
+
+        if ((fbPath != NULL) && (*fbPath == '\0')) {
+            /* Autoconfigured fbdev device is incompatible with anything */
+            LogMessageVerb(X_INFO, 1,
+                "\"%s\" must be the only device, but \"%s\" is present.\n",
+                fb_ptr->identifier, pent->devices[0]->identifier);
+            return FALSE;
+        }
+
+#ifdef XSERVER_LIBPCIACCESS 
+        pci_other = xf86GetPciInfoForEntity(i);
+        /* First compare PCI addresses */
+        if (pci_ptr && pci_other) {
+            if (MATCH_PCI_DEVICES(pci_other, pci_ptr)) {
+            /* This PCI slot has been claimed, fail */
+                if (msPath) {
+                    LogMessageVerb(X_INFO, 1,
+                        " Platform device \"%s\" skipped because\n",
+                        msPath);
+                }
+                else {
+                    LogMessageVerb(X_INFO, 1,
+                        " PCI device skipped because\n");
+                }
+                LogMessageVerb(X_INFO, 1,
+                    "  PCI bus id %u@%u:%u:%u has already been claimed by \"%s\".\n",
+                    pci_ptr->domain, pci_ptr->bus, pci_ptr->dev, pci_ptr->func, 
+                    pent->devices[0]->identifier);
+                return FALSE;
+            }
+            else
+            /* This is another device, skip */
+                continue;
+        }
+
+        if (pent->bus.type == BUS_PCI) {
+            /* No other means to compare, accept */
+            continue;
+        }
+#endif
+
+        if (pent->bus.type == BUS_NONE) {
+            if (!strcasecmp(pent->driver->driverName, "fbdev")) {
+                if ((type != BUS_NONE) || (fbPath == NULL)) {
+                    /* fbdev without busID is incompatible with other types */
+                    LogMessageVerb(X_INFO, 1,
+                        " Only fbdev without PCI bus id can be claimed after \"%s\".\n",
+                        pent->devices[0]->identifier);
+                    return FALSE;
+                }
+                /* Examine the first device only */
+                fbOther = xf86FindOptionValue(pent->devices[0]->options, "fbdev");
+                if (fbOther == NULL) {
+                    /* Autoconfigured, reject */
+                    LogMessageVerb(X_INFO, 1,
+                        " Can\'t claim anything after \"%s\".\n",
+                        pent->devices[0]->identifier);
+                    return FALSE;
+                }
+                if (strcmp(fbPath, fbOther)) {
+                    /* No conflict */
+                    continue;
+                }
+                else {
+                    /* This framebuffer device has been claimed already */
+                    LogMessageVerb(X_INFO, 1,
+                        " Framebuffer device \"%s\" has already been claimed by \"%s\".\n",
+                        fbPath, pent->devices[0]->identifier);
+                    return FALSE;
+                }
+            }
+        }
+
+#ifdef XSERVER_PLATFORM_BUS
+        if (pent->bus.type == BUS_PLATFORM) {
+            msOther = pent->bus.id.plat->attribs->path;
+        } else
+#endif
+        if (pent->bus.type == BUS_NONE) {
+            if (!strcasecmp(pent->driver->driverName, "modesetting")) {
+                /* Examine the first device only */
+                msOther = xf86FindOptionValue(pent->devices[0]->options, "kmsdev");
+                if ((msOther == NULL) && (pci_other == NULL)) {
+                    /* Autoconfigured */
+                    msOther = "/dev/dri/card0";
+                }
+            }
+        }
+
+        if ((msPath != NULL) && (msOther != NULL) && !strcmp(msPath, msOther)) {
+            /* This DRI device has been claimed already */
+                    LogMessageVerb(X_INFO, 1,
+                        " DRI device \"%s\" has already been claimed by \"%s\".\n",
+                        msPath, pent->devices[0]->identifier);
+            return FALSE;
+        }
+    }
+
+#ifdef XSERVER_PLATFORM_BUS
+    if (type == BUS_PLATFORM) {
+        if (pci_ptr)
+            LogMessageVerb(X_INFO, 1,
+                " Platform device \"%s\" at %u@%u:%u:%u can be claimed.\n",
+                msPath, pci_ptr->domain, pci_ptr->bus, pci_ptr->dev, pci_ptr->func);
+        else
+            LogMessageVerb(X_INFO, 1,
+                " Platform device \"%s\" can be claimed.\n",
+                 msPath);
+    }
+    else
+#endif
+#ifdef XSERVER_LIBPCIACCESS 
+    if (type == BUS_PCI) {
+        LogMessageVerb(X_INFO, 1,
+            " PCI device %u@%u:%u:%u can be claimed.\n",
+            pci_ptr->domain, pci_ptr->bus, pci_ptr->dev, pci_ptr->func);
+    }
+    else
+#endif
+    if (type == BUS_NONE) {
+        if (msPath)
+            LogMessageVerb(X_INFO, 1,
+                "\"%s\" can be claimed by modesetting driver as \"%s\".\n",
+                msPath, fb_ptr->identifier);
+        else
+        if (fbPath)
+            LogMessageVerb(X_INFO, 1,
+                "\"%s\" can be claimed by fbdev driver as \"%s\".\n",
+                fbPath, fb_ptr->identifier);
+        else
+            LogMessageVerb(X_INFO, 1,
+                "\"%s\" can be claimed.\n",
+                 fb_ptr->identifier);
+    }
+
+    return TRUE;
+}
diff --git a/hw/xfree86/common/xf86Bus.h b/hw/xfree86/common/xf86Bus.h
index d8e8bf3e2..933bef492 100644
--- a/hw/xfree86/common/xf86Bus.h
+++ b/hw/xfree86/common/xf86Bus.h
@@ -83,4 +83,5 @@ void xf86RemoveDevFromEntity(int entityIndex, GDevPtr dev);
 
 Bool xf86CallDriverProbe(struct _DriverRec *drv, Bool detect_only);
 
+Bool xf86CheckSlot(const void *ptr, BusType type);
 #endif                          /* _XF86_BUS_H */
diff --git a/hw/xfree86/common/xf86fbBus.c b/hw/xfree86/common/xf86fbBus.c
index 22825d8ae..7dbd5ac2c 100644
--- a/hw/xfree86/common/xf86fbBus.c
+++ b/hw/xfree86/common/xf86fbBus.c
@@ -50,14 +50,18 @@ xf86ClaimFbSlot(DriverPtr drvp, int chipset, GDevPtr dev, Bool active)
     EntityPtr p;
     int num;
 
-    num = xf86AllocateEntity();
-    p = xf86Entities[num];
-    p->driver = drvp;
-    p->chipset = 0;
-    p->bus.type = BUS_NONE;
-    p->active = active;
-    p->inUse = FALSE;
-    xf86AddDevToEntity(num, dev);
+    if (xf86CheckSlot(dev, BUS_NONE)) {
+        num = xf86AllocateEntity();
+        p = xf86Entities[num];
+        p->driver = drvp;
+        p->chipset = 0;
+        p->bus.type = BUS_NONE;
+        p->active = active;
+        p->inUse = FALSE;
+        xf86AddDevToEntity(num, dev);
 
-    return num;
+        return num;
+    } else {
+        return -1;
+    }
 }
diff --git a/hw/xfree86/common/xf86pciBus.c b/hw/xfree86/common/xf86pciBus.c
index 62648efaf..9e697146e 100644
--- a/hw/xfree86/common/xf86pciBus.c
+++ b/hw/xfree86/common/xf86pciBus.c
@@ -411,23 +411,7 @@ xf86CheckPciMemBase(struct pci_device *pPci, memType base)
 Bool
 xf86CheckPciSlot(const struct pci_device *d)
 {
-    int i;
-
-    for (i = 0; i < xf86NumEntities; i++) {
-        const EntityPtr p = xf86Entities[i];
-
-        if ((p->bus.type == BUS_PCI) && (p->bus.id.pci == d)) {
-            return FALSE;
-        }
-#ifdef XSERVER_PLATFORM_BUS
-        if ((p->bus.type == BUS_PLATFORM) && (p->bus.id.plat->pdev)) {
-            struct pci_device *ud = p->bus.id.plat->pdev;
-            if (MATCH_PCI_DEVICES(ud, d))
-                return FALSE;
-        }
-#endif
-    }
-    return TRUE;
+    return xf86CheckSlot(d, BUS_PCI);
 }
 
 #define END_OF_MATCHES(m) \
diff --git a/hw/xfree86/common/xf86platformBus.c b/hw/xfree86/common/xf86platformBus.c
index e8cf44178..1fd4514a3 100644
--- a/hw/xfree86/common/xf86platformBus.c
+++ b/hw/xfree86/common/xf86platformBus.c
@@ -155,25 +155,6 @@ platform_find_pci_info(struct xf86_platform_device *pd, char *busid)
     pci_iterator_destroy(iter);
 }
 
-static Bool
-xf86_check_platform_slot(const struct xf86_platform_device *pd)
-{
-    int i;
-
-    for (i = 0; i < xf86NumEntities; i++) {
-        const EntityPtr u = xf86Entities[i];
-
-        if (pd->pdev && u->bus.type == BUS_PCI &&
-            MATCH_PCI_DEVICES(pd->pdev, u->bus.id.pci)) {
-            return FALSE;
-        }
-        if ((u->bus.type == BUS_PLATFORM) && (pd == u->bus.id.plat)) {
-            return FALSE;
-        }
-    }
-    return TRUE;
-}
-
 static Bool
 OutputClassMatches(const XF86ConfOutputClassPtr oclass,
                    struct xf86_platform_device *dev)
@@ -465,7 +446,7 @@ xf86ClaimPlatformSlot(struct xf86_platform_device * d, DriverPtr drvp,
     EntityPtr p = NULL;
     int num;
 
-    if (xf86_check_platform_slot(d)) {
+    if (xf86CheckSlot(d, BUS_PLATFORM)) {
         num = xf86AllocateEntity();
         p = xf86Entities[num];
         p->driver = drvp;
@@ -511,27 +492,29 @@ static Bool doPlatformProbe(struct xf86_platform_device *dev, DriverPtr drvp,
     Bool foundScreen = FALSE;
     int entity;
 
-    if (gdev && gdev->screen == 0 && !xf86_check_platform_slot(dev))
-        return FALSE;
-
     entity = xf86ClaimPlatformSlot(dev, drvp, 0,
                                    gdev, gdev ? gdev->active : 0);
 
-    if ((entity == -1) && gdev && (gdev->screen > 0)) {
-        unsigned nent;
+    if ((entity == -1) && gdev) {
+        if (gdev->screen == 0)
+            return FALSE;
+        else { /* gdev->screen > 0 */
+            unsigned nent;
 
-        for (nent = 0; nent < xf86NumEntities; nent++) {
-            EntityPtr pEnt = xf86Entities[nent];
+            for (nent = 0; nent < xf86NumEntities; nent++) {
+                EntityPtr pEnt = xf86Entities[nent];
 
-            if (pEnt->bus.type != BUS_PLATFORM)
-                continue;
-            if (pEnt->bus.id.plat == dev) {
-                entity = nent;
-                xf86AddDevToEntity(nent, gdev);
-                break;
+                if (pEnt->bus.type != BUS_PLATFORM)
+                    continue;
+                if (pEnt->bus.id.plat == dev) {
+                    entity = nent;
+                    xf86AddDevToEntity(nent, gdev);
+                    break;
+                }
             }
         }
     }
+
     if (entity != -1) {
         if ((dev->flags & XF86_PDEV_SERVER_FD) && (!drvp->driverFunc ||
                 !drvp->driverFunc(NULL, SUPPORTS_SERVER_FDS, NULL))) {