x86: when choosing PCI starting address, print out gap information

This makes for better messages on what is going on. It also
allows us (if we want to), to pick the PCI starting address
somewhere else in the gap. That may be a good idea (ie do a

	pci_mem_start = (gapstart + (gapsize >> 3) + 0xfffff) & ~0xfffff;

or similar.

arch/i386/kernel/setup.c

@@ -1168,7 +1168,7 @@ legacy_init_iomem_resources(struct resource *code_resource, struct resource *dat
  */
 static void __init register_memory(void)
 {
-	unsigned long gapsize;
+	unsigned long gapstart, gapsize;
 	unsigned long long last;
 	int	      i;
 
@@ -1184,8 +1184,12 @@ static void __init register_memory(void)
 	for (i = 0; i < STANDARD_IO_RESOURCES; i++)
 		request_resource(&ioport_resource, &standard_io_resources[i]);
 
-	/* Tell the PCI layer not to allocate too close to the RAM area.. */
+	/*
+	 * Search for the bigest gap in the low 32 bits of the e820
+	 * memory space.
+	 */
 	last = 0x100000000ull;
+	gapstart = 0x10000000;
 	gapsize = 0x400000;
 	i = e820.nr_map;
 	while (--i >= 0) {
@@ -1201,13 +1205,25 @@ static void __init register_memory(void)
 
 			if (gap > gapsize) {
 				gapsize = gap;
-				pci_mem_start = ((unsigned long) end + 0xfffff) & ~0xfffff;
+				gapstart = end;
 			}
 		}
 		if (start < last)
 			last = start;
 	}
-	printk("Allocating PCI resources starting at %08lx\n", pci_mem_start);
+
+	/*
+	 * Start allocating dynamic PCI memory a bit into the gap,
+	 * aligned up to the nearest megabyte.
+	 *
+	 * Question: should we try to pad it up a bit (do something
+	 * like " + (gapsize >> 3)" in there too?). We now have the
+	 * technology.
+	 */
+	pci_mem_start = (gapstart + 0xfffff) & ~0xfffff;
+
+	printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
+		pci_mem_start, gapstart, gapsize);
 }
 
 /* Use inline assembly to define this because the nops are defined