X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fx86_64%2Fkernel%2Fe820-xen.c;fp=arch%2Fx86_64%2Fkernel%2Fe820-xen.c;h=1e0b67b02f308fe5aba6f510d896b20b2b1e57c7;hb=1db395853d4f30d6120458bd279ede1f882a8525;hp=0000000000000000000000000000000000000000;hpb=34a75f0025b9cf803b6a88db032e6ad6950c9313;p=linux-2.6.git

diff --git a/arch/x86_64/kernel/e820-xen.c b/arch/x86_64/kernel/e820-xen.c
new file mode 100644
index 000000000..1e0b67b02
--- /dev/null
+++ b/arch/x86_64/kernel/e820-xen.c
@@ -0,0 +1,753 @@
+/* 
+ * Handle the memory map.
+ * The functions here do the job until bootmem takes over.
+ * $Id: e820.c,v 1.4 2002/09/19 19:25:32 ak Exp $
+ *
+ *  Getting sanitize_e820_map() in sync with i386 version by applying change:
+ *  -  Provisions for empty E820 memory regions (reported by certain BIOSes).
+ *     Alex Achenbach <xela@slit.de>, December 2002.
+ *  Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ *
+ */
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/ioport.h>
+#include <linux/string.h>
+#include <linux/kexec.h>
+#include <linux/module.h>
+
+#include <asm/page.h>
+#include <asm/e820.h>
+#include <asm/proto.h>
+#include <asm/bootsetup.h>
+#include <asm/sections.h>
+#include <xen/interface/memory.h>
+
+/* 
+ * PFN of last memory page.
+ */
+unsigned long end_pfn; 
+EXPORT_SYMBOL(end_pfn);
+
+/* 
+ * end_pfn only includes RAM, while end_pfn_map includes all e820 entries.
+ * The direct mapping extends to end_pfn_map, so that we can directly access
+ * apertures, ACPI and other tables without having to play with fixmaps.
+ */ 
+unsigned long end_pfn_map; 
+
+/* 
+ * Last pfn which the user wants to use.
+ */
+unsigned long end_user_pfn = MAXMEM>>PAGE_SHIFT;  
+
+extern struct resource code_resource, data_resource;
+
+/* Check for some hardcoded bad areas that early boot is not allowed to touch */ 
+static inline int bad_addr(unsigned long *addrp, unsigned long size)
+{ 
+	unsigned long addr = *addrp, last = addr + size; 
+
+#ifndef CONFIG_XEN
+	/* various gunk below that needed for SMP startup */
+	if (addr < 0x8000) { 
+		*addrp = 0x8000;
+		return 1; 
+	}
+
+	/* direct mapping tables of the kernel */
+	if (last >= table_start<<PAGE_SHIFT && addr < table_end<<PAGE_SHIFT) { 
+		*addrp = table_end << PAGE_SHIFT; 
+		return 1;
+	} 
+
+	/* initrd */ 
+#ifdef CONFIG_BLK_DEV_INITRD
+	if (LOADER_TYPE && INITRD_START && last >= INITRD_START && 
+	    addr < INITRD_START+INITRD_SIZE) { 
+		*addrp = INITRD_START + INITRD_SIZE; 
+		return 1;
+	} 
+#endif
+	/* kernel code + 640k memory hole (later should not be needed, but 
+	   be paranoid for now) */
+	if (last >= 640*1024 && addr < __pa_symbol(&_end)) { 
+		*addrp = __pa_symbol(&_end);
+		return 1;
+	}
+
+	if (last >= ebda_addr && addr < ebda_addr + ebda_size) {
+		*addrp = ebda_addr + ebda_size;
+		return 1;
+	}
+
+	/* XXX ramdisk image here? */ 
+#else
+	if (last < (table_end<<PAGE_SHIFT)) {
+		*addrp = table_end << PAGE_SHIFT;
+		return 1;
+	}
+#endif
+	return 0;
+} 
+
+#ifndef CONFIG_XEN
+/*
+ * This function checks if any part of the range <start,end> is mapped
+ * with type.
+ */
+int __meminit
+e820_any_mapped(unsigned long start, unsigned long end, unsigned type)
+{ 
+	int i;
+	for (i = 0; i < e820.nr_map; i++) { 
+		struct e820entry *ei = &e820.map[i]; 
+		if (type && ei->type != type) 
+			continue;
+		if (ei->addr >= end || ei->addr + ei->size <= start)
+			continue; 
+		return 1; 
+	} 
+	return 0;
+}
+#endif
+
+/*
+ * This function checks if the entire range <start,end> is mapped with type.
+ *
+ * Note: this function only works correct if the e820 table is sorted and
+ * not-overlapping, which is the case
+ */
+int __init e820_all_mapped(unsigned long start, unsigned long end, unsigned type)
+{
+	int i;
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		if (type && ei->type != type)
+			continue;
+		/* is the region (part) in overlap with the current region ?*/
+		if (ei->addr >= end || ei->addr + ei->size <= start)
+			continue;
+
+		/* if the region is at the beginning of <start,end> we move
+		 * start to the end of the region since it's ok until there
+		 */
+		if (ei->addr <= start)
+			start = ei->addr + ei->size;
+		/* if start is now at or beyond end, we're done, full coverage */
+		if (start >= end)
+			return 1; /* we're done */
+	}
+	return 0;
+}
+
+/* 
+ * Find a free area in a specific range. 
+ */ 
+unsigned long __init find_e820_area(unsigned long start, unsigned long end, unsigned size) 
+{ 
+	int i; 
+	for (i = 0; i < e820.nr_map; i++) { 
+		struct e820entry *ei = &e820.map[i]; 
+		unsigned long addr = ei->addr, last; 
+		if (ei->type != E820_RAM) 
+			continue; 
+		if (addr < start) 
+			addr = start;
+		if (addr > ei->addr + ei->size) 
+			continue; 
+		while (bad_addr(&addr, size) && addr+size < ei->addr + ei->size)
+			;
+		last = addr + size;
+		if (last > ei->addr + ei->size)
+			continue;
+		if (last > end) 
+			continue;
+		return addr; 
+	} 
+	return -1UL;		
+} 
+
+/* 
+ * Free bootmem based on the e820 table for a node.
+ */
+void __init e820_bootmem_free(pg_data_t *pgdat, unsigned long start,unsigned long end)
+{
+	int i;
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i]; 
+		unsigned long last, addr;
+
+		if (ei->type != E820_RAM || 
+		    ei->addr+ei->size <= start || 
+		    ei->addr >= end)
+			continue;
+
+		addr = round_up(ei->addr, PAGE_SIZE);
+		if (addr < start) 
+			addr = start;
+
+		last = round_down(ei->addr + ei->size, PAGE_SIZE); 
+		if (last >= end)
+			last = end; 
+
+		if (last > addr && last-addr >= PAGE_SIZE)
+			free_bootmem_node(pgdat, addr, last-addr);
+	}
+}
+
+/*
+ * Find the highest page frame number we have available
+ */
+unsigned long __init e820_end_of_ram(void)
+{
+	int i;
+	unsigned long end_pfn = 0;
+	
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i]; 
+		unsigned long start, end;
+
+		start = round_up(ei->addr, PAGE_SIZE); 
+		end = round_down(ei->addr + ei->size, PAGE_SIZE); 
+		if (start >= end)
+			continue;
+		if (ei->type == E820_RAM) { 
+		if (end > end_pfn<<PAGE_SHIFT)
+			end_pfn = end>>PAGE_SHIFT;
+		} else { 
+			if (end > end_pfn_map<<PAGE_SHIFT) 
+				end_pfn_map = end>>PAGE_SHIFT;
+		} 
+	}
+
+	if (end_pfn > end_pfn_map) 
+		end_pfn_map = end_pfn;
+	if (end_pfn_map > MAXMEM>>PAGE_SHIFT)
+		end_pfn_map = MAXMEM>>PAGE_SHIFT;
+	if (end_pfn > end_user_pfn)
+		end_pfn = end_user_pfn;
+	if (end_pfn > end_pfn_map) 
+		end_pfn = end_pfn_map; 
+
+	return end_pfn;	
+}
+
+/* 
+ * Compute how much memory is missing in a range.
+ * Unlike the other functions in this file the arguments are in page numbers.
+ */
+unsigned long __init
+e820_hole_size(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long ram = 0;
+	unsigned long start = start_pfn << PAGE_SHIFT;
+	unsigned long end = end_pfn << PAGE_SHIFT;
+	int i;
+	for (i = 0; i < e820.nr_map; i++) {
+		struct e820entry *ei = &e820.map[i];
+		unsigned long last, addr;
+
+		if (ei->type != E820_RAM ||
+		    ei->addr+ei->size <= start ||
+		    ei->addr >= end)
+			continue;
+
+		addr = round_up(ei->addr, PAGE_SIZE);
+		if (addr < start)
+			addr = start;
+
+		last = round_down(ei->addr + ei->size, PAGE_SIZE);
+		if (last >= end)
+			last = end;
+
+		if (last > addr)
+			ram += last - addr;
+	}
+	return ((end - start) - ram) >> PAGE_SHIFT;
+}
+
+/*
+ * Mark e820 reserved areas as busy for the resource manager.
+ */
+void __init e820_reserve_resources(struct e820entry *e820, int nr_map)
+{
+	int i;
+	for (i = 0; i < nr_map; i++) {
+		struct resource *res;
+		res = alloc_bootmem_low(sizeof(struct resource));
+		switch (e820[i].type) {
+		case E820_RAM:	res->name = "System RAM"; break;
+		case E820_ACPI:	res->name = "ACPI Tables"; break;
+		case E820_NVS:	res->name = "ACPI Non-volatile Storage"; break;
+		default:	res->name = "reserved";
+		}
+		res->start = e820[i].addr;
+		res->end = res->start + e820[i].size - 1;
+		res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+		request_resource(&iomem_resource, res);
+		if (e820[i].type == E820_RAM) {
+			/*
+			 *  We don't know which RAM region contains kernel data,
+			 *  so we try it repeatedly and let the resource manager
+			 *  test it.
+			 */
+			request_resource(res, &code_resource);
+			request_resource(res, &data_resource);
+#ifdef CONFIG_KEXEC
+			request_resource(res, &crashk_res);
+#endif
+		}
+	}
+}
+
+/* 
+ * Add a memory region to the kernel e820 map.
+ */ 
+void __init add_memory_region(unsigned long start, unsigned long size, int type)
+{
+	int x = e820.nr_map;
+
+	if (x == E820MAX) {
+		printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
+		return;
+	}
+
+	e820.map[x].addr = start;
+	e820.map[x].size = size;
+	e820.map[x].type = type;
+	e820.nr_map++;
+}
+
+void __init e820_print_map(char *who)
+{
+	int i;
+
+	for (i = 0; i < e820.nr_map; i++) {
+		printk(" %s: %016Lx - %016Lx ", who,
+			(unsigned long long) e820.map[i].addr,
+			(unsigned long long) (e820.map[i].addr + e820.map[i].size));
+		switch (e820.map[i].type) {
+		case E820_RAM:	printk("(usable)\n");
+				break;
+		case E820_RESERVED:
+				printk("(reserved)\n");
+				break;
+		case E820_ACPI:
+				printk("(ACPI data)\n");
+				break;
+		case E820_NVS:
+				printk("(ACPI NVS)\n");
+				break;
+		default:	printk("type %u\n", e820.map[i].type);
+				break;
+		}
+	}
+}
+
+/*
+ * Sanitize the BIOS e820 map.
+ *
+ * Some e820 responses include overlapping entries.  The following 
+ * replaces the original e820 map with a new one, removing overlaps.
+ *
+ */
+static int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
+{
+	struct change_member {
+		struct e820entry *pbios; /* pointer to original bios entry */
+		unsigned long long addr; /* address for this change point */
+	};
+	static struct change_member change_point_list[2*E820MAX] __initdata;
+	static struct change_member *change_point[2*E820MAX] __initdata;
+	static struct e820entry *overlap_list[E820MAX] __initdata;
+	static struct e820entry new_bios[E820MAX] __initdata;
+	struct change_member *change_tmp;
+	unsigned long current_type, last_type;
+	unsigned long long last_addr;
+	int chgidx, still_changing;
+	int overlap_entries;
+	int new_bios_entry;
+	int old_nr, new_nr, chg_nr;
+	int i;
+
+	/*
+		Visually we're performing the following (1,2,3,4 = memory types)...
+
+		Sample memory map (w/overlaps):
+		   ____22__________________
+		   ______________________4_
+		   ____1111________________
+		   _44_____________________
+		   11111111________________
+		   ____________________33__
+		   ___________44___________
+		   __________33333_________
+		   ______________22________
+		   ___________________2222_
+		   _________111111111______
+		   _____________________11_
+		   _________________4______
+
+		Sanitized equivalent (no overlap):
+		   1_______________________
+		   _44_____________________
+		   ___1____________________
+		   ____22__________________
+		   ______11________________
+		   _________1______________
+		   __________3_____________
+		   ___________44___________
+		   _____________33_________
+		   _______________2________
+		   ________________1_______
+		   _________________4______
+		   ___________________2____
+		   ____________________33__
+		   ______________________4_
+	*/
+
+	/* if there's only one memory region, don't bother */
+	if (*pnr_map < 2)
+		return -1;
+
+	old_nr = *pnr_map;
+
+	/* bail out if we find any unreasonable addresses in bios map */
+	for (i=0; i<old_nr; i++)
+		if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr)
+			return -1;
+
+	/* create pointers for initial change-point information (for sorting) */
+	for (i=0; i < 2*old_nr; i++)
+		change_point[i] = &change_point_list[i];
+
+	/* record all known change-points (starting and ending addresses),
+	   omitting those that are for empty memory regions */
+	chgidx = 0;
+	for (i=0; i < old_nr; i++)	{
+		if (biosmap[i].size != 0) {
+			change_point[chgidx]->addr = biosmap[i].addr;
+			change_point[chgidx++]->pbios = &biosmap[i];
+			change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
+			change_point[chgidx++]->pbios = &biosmap[i];
+		}
+	}
+	chg_nr = chgidx;
+
+	/* sort change-point list by memory addresses (low -> high) */
+	still_changing = 1;
+	while (still_changing)	{
+		still_changing = 0;
+		for (i=1; i < chg_nr; i++)  {
+			/* if <current_addr> > <last_addr>, swap */
+			/* or, if current=<start_addr> & last=<end_addr>, swap */
+			if ((change_point[i]->addr < change_point[i-1]->addr) ||
+				((change_point[i]->addr == change_point[i-1]->addr) &&
+				 (change_point[i]->addr == change_point[i]->pbios->addr) &&
+				 (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
+			   )
+			{
+				change_tmp = change_point[i];
+				change_point[i] = change_point[i-1];
+				change_point[i-1] = change_tmp;
+				still_changing=1;
+			}
+		}
+	}
+
+	/* create a new bios memory map, removing overlaps */
+	overlap_entries=0;	 /* number of entries in the overlap table */
+	new_bios_entry=0;	 /* index for creating new bios map entries */
+	last_type = 0;		 /* start with undefined memory type */
+	last_addr = 0;		 /* start with 0 as last starting address */
+	/* loop through change-points, determining affect on the new bios map */
+	for (chgidx=0; chgidx < chg_nr; chgidx++)
+	{
+		/* keep track of all overlapping bios entries */
+		if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
+		{
+			/* add map entry to overlap list (> 1 entry implies an overlap) */
+			overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
+		}
+		else
+		{
+			/* remove entry from list (order independent, so swap with last) */
+			for (i=0; i<overlap_entries; i++)
+			{
+				if (overlap_list[i] == change_point[chgidx]->pbios)
+					overlap_list[i] = overlap_list[overlap_entries-1];
+			}
+			overlap_entries--;
+		}
+		/* if there are overlapping entries, decide which "type" to use */
+		/* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
+		current_type = 0;
+		for (i=0; i<overlap_entries; i++)
+			if (overlap_list[i]->type > current_type)
+				current_type = overlap_list[i]->type;
+		/* continue building up new bios map based on this information */
+		if (current_type != last_type)	{
+			if (last_type != 0)	 {
+				new_bios[new_bios_entry].size =
+					change_point[chgidx]->addr - last_addr;
+				/* move forward only if the new size was non-zero */
+				if (new_bios[new_bios_entry].size != 0)
+					if (++new_bios_entry >= E820MAX)
+						break; 	/* no more space left for new bios entries */
+			}
+			if (current_type != 0)	{
+				new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
+				new_bios[new_bios_entry].type = current_type;
+				last_addr=change_point[chgidx]->addr;
+			}
+			last_type = current_type;
+		}
+	}
+	new_nr = new_bios_entry;   /* retain count for new bios entries */
+
+	/* copy new bios mapping into original location */
+	memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
+	*pnr_map = new_nr;
+
+	return 0;
+}
+
+/*
+ * Copy the BIOS e820 map into a safe place.
+ *
+ * Sanity-check it while we're at it..
+ *
+ * If we're lucky and live on a modern system, the setup code
+ * will have given us a memory map that we can use to properly
+ * set up memory.  If we aren't, we'll fake a memory map.
+ *
+ * We check to see that the memory map contains at least 2 elements
+ * before we'll use it, because the detection code in setup.S may
+ * not be perfect and most every PC known to man has two memory
+ * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
+ * thinkpad 560x, for example, does not cooperate with the memory
+ * detection code.)
+ */
+static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
+{
+#ifndef CONFIG_XEN
+	/* Only one memory region (or negative)? Ignore it */
+	if (nr_map < 2)
+		return -1;
+#else
+	BUG_ON(nr_map < 1);
+#endif
+
+	do {
+		unsigned long start = biosmap->addr;
+		unsigned long size = biosmap->size;
+		unsigned long end = start + size;
+		unsigned long type = biosmap->type;
+
+		/* Overflow in 64 bits? Ignore the memory map. */
+		if (start > end)
+			return -1;
+
+#ifndef CONFIG_XEN
+		/*
+		 * Some BIOSes claim RAM in the 640k - 1M region.
+		 * Not right. Fix it up.
+		 * 
+		 * This should be removed on Hammer which is supposed to not
+		 * have non e820 covered ISA mappings there, but I had some strange
+		 * problems so it stays for now.  -AK
+		 */
+		if (type == E820_RAM) {
+			if (start < 0x100000ULL && end > 0xA0000ULL) {
+				if (start < 0xA0000ULL)
+					add_memory_region(start, 0xA0000ULL-start, type);
+				if (end <= 0x100000ULL)
+					continue;
+				start = 0x100000ULL;
+				size = end - start;
+			}
+		}
+#endif
+
+		add_memory_region(start, size, type);
+	} while (biosmap++,--nr_map);
+	return 0;
+}
+
+#ifndef CONFIG_XEN
+void __init setup_memory_region(void)
+{
+	char *who = "BIOS-e820";
+
+	/*
+	 * Try to copy the BIOS-supplied E820-map.
+	 *
+	 * Otherwise fake a memory map; one section from 0k->640k,
+	 * the next section from 1mb->appropriate_mem_k
+	 */
+	sanitize_e820_map(E820_MAP, &E820_MAP_NR);
+	if (copy_e820_map(E820_MAP, E820_MAP_NR) < 0) {
+		unsigned long mem_size;
+
+		/* compare results from other methods and take the greater */
+		if (ALT_MEM_K < EXT_MEM_K) {
+			mem_size = EXT_MEM_K;
+			who = "BIOS-88";
+		} else {
+			mem_size = ALT_MEM_K;
+			who = "BIOS-e801";
+		}
+
+		e820.nr_map = 0;
+		add_memory_region(0, LOWMEMSIZE(), E820_RAM);
+		add_memory_region(HIGH_MEMORY, mem_size << 10, E820_RAM);
+  	}
+	printk(KERN_INFO "BIOS-provided physical RAM map:\n");
+	e820_print_map(who);
+}
+
+#else  /* CONFIG_XEN */
+
+void __init setup_memory_region(void)
+{
+	int rc;
+	struct xen_memory_map memmap;
+	/*
+	 * This is rather large for a stack variable but this early in
+	 * the boot process we know we have plenty slack space.
+	 */
+	struct e820entry map[E820MAX];
+
+	memmap.nr_entries = E820MAX;
+	set_xen_guest_handle(memmap.buffer, map);
+
+	rc = HYPERVISOR_memory_op(XENMEM_memory_map, &memmap);
+	if ( rc == -ENOSYS ) {
+		memmap.nr_entries = 1;
+		map[0].addr = 0ULL;
+		map[0].size = xen_start_info->nr_pages << PAGE_SHIFT;
+		/* 8MB slack (to balance backend allocations). */
+		map[0].size += 8 << 20;
+		map[0].type = E820_RAM;
+		rc = 0;
+	}
+	BUG_ON(rc);
+
+	sanitize_e820_map(map, (char *)&memmap.nr_entries);
+
+	BUG_ON(copy_e820_map(map, (char)memmap.nr_entries) < 0);
+
+	printk(KERN_INFO "BIOS-provided physical RAM map:\n");
+	e820_print_map("Xen");
+}
+#endif
+
+void __init parse_memopt(char *p, char **from) 
+{ 
+	int i;
+	unsigned long current_end;
+	unsigned long end;
+
+	end_user_pfn = memparse(p, from);
+	end_user_pfn >>= PAGE_SHIFT;	
+
+	end = end_user_pfn<<PAGE_SHIFT;
+	i = e820.nr_map-1;
+	current_end = e820.map[i].addr + e820.map[i].size;
+
+	if (current_end < end) {
+		/*
+                 * The e820 map ends before our requested size so
+                 * extend the final entry to the requested address.
+                 */
+		if (e820.map[i].type == E820_RAM)
+			e820.map[i].size = end - e820.map[i].addr;
+		else
+			add_memory_region(current_end, end - current_end, E820_RAM);
+	}
+} 
+
+void __init parse_memmapopt(char *p, char **from)
+{
+	unsigned long long start_at, mem_size;
+
+	mem_size = memparse(p, from);
+	p = *from;
+	if (*p == '@') {
+		start_at = memparse(p+1, from);
+		add_memory_region(start_at, mem_size, E820_RAM);
+	} else if (*p == '#') {
+		start_at = memparse(p+1, from);
+		add_memory_region(start_at, mem_size, E820_ACPI);
+	} else if (*p == '$') {
+		start_at = memparse(p+1, from);
+		add_memory_region(start_at, mem_size, E820_RESERVED);
+	} else {
+		end_user_pfn = (mem_size >> PAGE_SHIFT);
+	}
+	p = *from;
+}
+
+unsigned long pci_mem_start = 0xaeedbabe;
+
+/*
+ * Search for the biggest gap in the low 32 bits of the e820
+ * memory space.  We pass this space to PCI to assign MMIO resources
+ * for hotplug or unconfigured devices in.
+ * Hopefully the BIOS let enough space left.
+ */
+__init void e820_setup_gap(struct e820entry *e820, int nr_map)
+{
+	unsigned long gapstart, gapsize, round;
+	unsigned long last;
+	int i;
+	int found = 0;
+
+	last = 0x100000000ull;
+	gapstart = 0x10000000;
+	gapsize = 0x400000;
+	i = nr_map;
+	while (--i >= 0) {
+		unsigned long long start = e820[i].addr;
+		unsigned long long end = start + e820[i].size;
+
+		/*
+		 * Since "last" is at most 4GB, we know we'll
+		 * fit in 32 bits if this condition is true
+		 */
+		if (last > end) {
+			unsigned long gap = last - end;
+
+			if (gap > gapsize) {
+				gapsize = gap;
+				gapstart = end;
+				found = 1;
+			}
+		}
+		if (start < last)
+			last = start;
+	}
+
+	if (!found) {
+		gapstart = (end_pfn << PAGE_SHIFT) + 1024*1024;
+		printk(KERN_ERR "PCI: Warning: Cannot find a gap in the 32bit address range\n"
+		       KERN_ERR "PCI: Unassigned devices with 32bit resource registers may break!\n");
+	}
+
+	/*
+	 * See how much we want to round up: start off with
+	 * rounding to the next 1MB area.
+	 */
+	round = 0x100000;
+	while ((gapsize >> 4) > round)
+		round += round;
+	/* Fun with two's complement */
+	pci_mem_start = (gapstart + round) & -round;
+
+	printk(KERN_INFO "Allocating PCI resources starting at %lx (gap: %lx:%lx)\n",
+		pci_mem_start, gapstart, gapsize);
+}