Index: sys/dev/pci/pci_map.c
===================================================================
RCS file: /cvsroot/src/sys/dev/pci/pci_map.c,v
retrieving revision 1.32
diff -p -u -r1.32 pci_map.c
--- sys/dev/pci/pci_map.c	26 Dec 2014 05:09:03 -0000	1.32
+++ sys/dev/pci/pci_map.c	17 Jan 2016 01:13:03 -0000
@@ -288,6 +288,7 @@ pci_mapreg_submap(const struct pci_attac
 	bus_addr_t base;
 	bus_size_t size;
 	int flags;
+	int error;
 
 	if (PCI_MAPREG_TYPE(type) == PCI_MAPREG_TYPE_IO) {
 		if ((pa->pa_flags & PCI_FLAGS_IO_OKAY) == 0)
@@ -309,6 +310,10 @@ pci_mapreg_submap(const struct pci_attac
 		pcireg_t 	mask;
 		int		s;
 		/* we have to enable the ROM address decoder... */
+		char devinfo[256];
+		pci_devinfo(pa->pa_id, pa->pa_class, false, devinfo,
+		    sizeof devinfo);
+		printf("pci: %s: enabling rom decoder\n", devinfo);
 		s = splhigh();
 		mask = pci_conf_read(pa->pa_pc, pa->pa_tag, reg);
 		mask |= PCI_MAPREG_ROM_ENABLE;
@@ -326,8 +331,17 @@ pci_mapreg_submap(const struct pci_attac
 	if ((size < maxsize) || (size < (offset + maxsize)))
 		return 1;
 
-	if (bus_space_map(tag, base, maxsize, busflags | flags, &handle))
+	error = bus_space_map(tag, base, maxsize, busflags | flags, &handle);
+	if (error) {
+		if (reg == PCI_MAPREG_ROM) {
+			char devinfo[256];
+			pci_devinfo(pa->pa_id, pa->pa_class, false, devinfo,
+			    sizeof devinfo);
+			printf("pci: %s: map ROM failed: %d\n", devinfo,
+			    error);
+		}
 		return 1;
+	}
 
 	if (tagp != NULL)
 		*tagp = tag;
@@ -350,12 +364,17 @@ pci_find_rom(const struct pci_attach_arg
 	uint16_t	ptr;
 	int		done = 0;
 
+	printf("pci_find_rom: size %"PRIuMAX"\n", (uintmax_t)sz);
+
 	/*
 	 * no upper bound check; i cannot imagine a 4GB ROM, but
 	 * it appears the spec would allow it!
 	 */
-	if (sz < 1024)
+	if (sz < 1024) {
+		printf("pci_find_rom: size too small: %"PRIuMAX" < 1024",
+		    (uintmax_t)sz);
 		return 1;
+	}
 
 	while (offset < sz && !done){
 		struct pci_rom_header	hdr;
@@ -367,8 +386,14 @@ pci_find_rom(const struct pci_attach_arg
 		    offset + offsetof (struct pci_rom_header, romh_data_ptr));
 
 		/* no warning: quite possibly ROM is simply not populated */
-		if (hdr.romh_magic != PCI_ROM_HEADER_MAGIC)
+		if (hdr.romh_magic != PCI_ROM_HEADER_MAGIC) {
+			printf("pci_find_rom: bad magic: %04"PRIx16
+			    "at %"PRIxMAX"\n",
+			    hdr.romh_magic,
+			    (uintmax_t)(bsh + offset +
+				offsetof(struct pci_rom_header, romh_magic)));
 			return 1;
+		}
 
 		ptr = offset + hdr.romh_data_ptr;
 		
@@ -414,11 +439,15 @@ pci_find_rom(const struct pci_attach_arg
 		}
 		
 		/* last image check */
-		if (rom.rom_indicator & PCI_ROM_INDICATOR_LAST)
+		if (rom.rom_indicator & PCI_ROM_INDICATOR_LAST) {
+			printf("pci_find_rom: rom indicator check failed\n");
 			return 1;
+		}
 
 		/* offset by size */
 		offset += imagesz;
 	}
+
+	printf("pci_find_rom: no rom found\n");
 	return 1;
 }