x86_64: prepare shared kernel/e820.c
authorThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:14:27 +0000 (11:14 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Thu, 11 Oct 2007 09:14:27 +0000 (11:14 +0200)
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
arch/x86_64/kernel/Makefile
arch/x86_64/kernel/e820.c [deleted file]
arch/x86_64/kernel/e820_64.c [new file with mode: 0644]

index e717a324bd8a1687915efe4cc040e6fe9b8aa637..e290dfa84004256c98913dec0d0675753993b092 100644 (file)
@@ -7,7 +7,7 @@ EXTRA_AFLAGS    := -traditional
 obj-y  := process.o signal.o entry.o traps_64.o irq.o \
                ptrace.o time.o ioport.o ldt.o setup.o i8259_64.o sys_x86_64.o \
                x8664_ksyms.o i387.o syscall.o vsyscall.o \
-               setup64.o bootflag.o e820.o reboot.o quirks.o i8237.o \
+               setup64.o bootflag.o e820_64.o reboot.o quirks.o i8237.o \
                pci-dma_64.o pci-nommu.o alternative.o hpet_64.o tsc.o bugs.o \
                perfctr-watchdog.o
 
diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c
deleted file mode 100644 (file)
index 0f4d5e2..0000000
+++ /dev/null
@@ -1,725 +0,0 @@
-/* 
- * Handle the memory map.
- * The functions here do the job until bootmem takes over.
- *
- *  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/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 <linux/mm.h>
-#include <linux/suspend.h>
-#include <linux/pfn.h>
-
-#include <asm/pgtable.h>
-#include <asm/page.h>
-#include <asm/e820.h>
-#include <asm/proto.h>
-#include <asm/bootsetup.h>
-#include <asm/sections.h>
-
-struct e820map e820;
-
-/* 
- * 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.
- */
-static unsigned long __initdata 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; 
-
-       /* various gunk below that needed for SMP startup */
-       if (addr < 0x8000) { 
-               *addrp = PAGE_ALIGN(0x8000);
-               return 1; 
-       }
-
-       /* direct mapping tables of the kernel */
-       if (last >= table_start<<PAGE_SHIFT && addr < table_end<<PAGE_SHIFT) { 
-               *addrp = PAGE_ALIGN(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 = PAGE_ALIGN(INITRD_START + INITRD_SIZE);
-               return 1;
-       } 
-#endif
-       /* kernel code */
-       if (last >= __pa_symbol(&_text) && addr < __pa_symbol(&_end)) {
-               *addrp = PAGE_ALIGN(__pa_symbol(&_end));
-               return 1;
-       }
-
-       if (last >= ebda_addr && addr < ebda_addr + ebda_size) {
-               *addrp = PAGE_ALIGN(ebda_addr + ebda_size);
-               return 1;
-       }
-
-#ifdef CONFIG_NUMA
-       /* NUMA memory to node map */
-       if (last >= nodemap_addr && addr < nodemap_addr + nodemap_size) {
-               *addrp = nodemap_addr + nodemap_size;
-               return 1;
-       }
-#endif
-       /* XXX ramdisk image here? */ 
-       return 0;
-} 
-
-/*
- * This function checks if any part of the range <start,end> is mapped
- * with type.
- */
-int
-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;
-}
-EXPORT_SYMBOL_GPL(e820_any_mapped);
-
-/*
- * 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 = PAGE_ALIGN(addr) + size;
-               if (last > ei->addr + ei->size)
-                       continue;
-               if (last > end) 
-                       continue;
-               return addr; 
-       } 
-       return -1UL;            
-} 
-
-/*
- * Find the highest page frame number we have available
- */
-unsigned long __init e820_end_of_ram(void)
-{
-       unsigned long end_pfn = 0;
-       end_pfn = find_max_pfn_with_active_regions();
-       
-       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; 
-
-       printk("end_pfn_map = %lu\n", end_pfn_map);
-       return end_pfn; 
-}
-
-/*
- * Mark e820 reserved areas as busy for the resource manager.
- */
-void __init e820_reserve_resources(void)
-{
-       int i;
-       for (i = 0; i < e820.nr_map; i++) {
-               struct resource *res;
-               res = alloc_bootmem_low(sizeof(struct resource));
-               switch (e820.map[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.map[i].addr;
-               res->end = res->start + e820.map[i].size - 1;
-               res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
-               request_resource(&iomem_resource, res);
-               if (e820.map[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
-               }
-       }
-}
-
-/*
- * Find the ranges of physical addresses that do not correspond to
- * e820 RAM areas and mark the corresponding pages as nosave for software
- * suspend and suspend to RAM.
- *
- * This function requires the e820 map to be sorted and without any
- * overlapping entries and assumes the first e820 area to be RAM.
- */
-void __init e820_mark_nosave_regions(void)
-{
-       int i;
-       unsigned long paddr;
-
-       paddr = round_down(e820.map[0].addr + e820.map[0].size, PAGE_SIZE);
-       for (i = 1; i < e820.nr_map; i++) {
-               struct e820entry *ei = &e820.map[i];
-
-               if (paddr < ei->addr)
-                       register_nosave_region(PFN_DOWN(paddr),
-                                               PFN_UP(ei->addr));
-
-               paddr = round_down(ei->addr + ei->size, PAGE_SIZE);
-               if (ei->type != E820_RAM)
-                       register_nosave_region(PFN_UP(ei->addr),
-                                               PFN_DOWN(paddr));
-
-               if (paddr >= (end_pfn << PAGE_SHIFT))
-                       break;
-       }
-}
-
-/*
- * Finds an active region in the address range from start_pfn to end_pfn and
- * returns its range in ei_startpfn and ei_endpfn for the e820 entry.
- */
-static int __init e820_find_active_region(const struct e820entry *ei,
-                                         unsigned long start_pfn,
-                                         unsigned long end_pfn,
-                                         unsigned long *ei_startpfn,
-                                         unsigned long *ei_endpfn)
-{
-       *ei_startpfn = round_up(ei->addr, PAGE_SIZE) >> PAGE_SHIFT;
-       *ei_endpfn = round_down(ei->addr + ei->size, PAGE_SIZE) >> PAGE_SHIFT;
-
-       /* Skip map entries smaller than a page */
-       if (*ei_startpfn >= *ei_endpfn)
-               return 0;
-
-       /* Check if end_pfn_map should be updated */
-       if (ei->type != E820_RAM && *ei_endpfn > end_pfn_map)
-               end_pfn_map = *ei_endpfn;
-
-       /* Skip if map is outside the node */
-       if (ei->type != E820_RAM || *ei_endpfn <= start_pfn ||
-                                   *ei_startpfn >= end_pfn)
-               return 0;
-
-       /* Check for overlaps */
-       if (*ei_startpfn < start_pfn)
-               *ei_startpfn = start_pfn;
-       if (*ei_endpfn > end_pfn)
-               *ei_endpfn = end_pfn;
-
-       /* Obey end_user_pfn to save on memmap */
-       if (*ei_startpfn >= end_user_pfn)
-               return 0;
-       if (*ei_endpfn > end_user_pfn)
-               *ei_endpfn = end_user_pfn;
-
-       return 1;
-}
-
-/* Walk the e820 map and register active regions within a node */
-void __init
-e820_register_active_regions(int nid, unsigned long start_pfn,
-                                                       unsigned long end_pfn)
-{
-       unsigned long ei_startpfn;
-       unsigned long ei_endpfn;
-       int i;
-
-       for (i = 0; i < e820.nr_map; i++)
-               if (e820_find_active_region(&e820.map[i],
-                                           start_pfn, end_pfn,
-                                           &ei_startpfn, &ei_endpfn))
-                       add_active_range(nid, ei_startpfn, ei_endpfn);
-}
-
-/* 
- * 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++;
-}
-
-/*
- * Find the hole size (in bytes) in the memory range.
- * @start: starting address of the memory range to scan
- * @end: ending address of the memory range to scan
- */
-unsigned long __init e820_hole_size(unsigned long start, unsigned long end)
-{
-       unsigned long start_pfn = start >> PAGE_SHIFT;
-       unsigned long end_pfn = end >> PAGE_SHIFT;
-       unsigned long ei_startpfn;
-       unsigned long ei_endpfn;
-       unsigned long ram = 0;
-       int i;
-
-       for (i = 0; i < e820.nr_map; i++) {
-               if (e820_find_active_region(&e820.map[i],
-                                           start_pfn, end_pfn,
-                                           &ei_startpfn, &ei_endpfn))
-                       ram += ei_endpfn - ei_startpfn;
-       }
-       return end - start - (ram << PAGE_SHIFT);
-}
-
-void __init e820_print_map(char *who)
-{
-       int i;
-
-       for (i = 0; i < e820.nr_map; i++) {
-               printk(KERN_INFO " %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.
- */
-static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
-{
-       /* Only one memory region (or negative)? Ignore it */
-       if (nr_map < 2)
-               return -1;
-
-       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;
-
-               add_memory_region(start, size, type);
-       } while (biosmap++,--nr_map);
-       return 0;
-}
-
-void early_panic(char *msg)
-{
-       early_printk(msg);
-       panic(msg);
-}
-
-void __init setup_memory_region(void)
-{
-       /*
-        * 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)
-               early_panic("Cannot find a valid memory map");
-       printk(KERN_INFO "BIOS-provided physical RAM map:\n");
-       e820_print_map("BIOS-e820");
-}
-
-static int __init parse_memopt(char *p)
-{
-       if (!p)
-               return -EINVAL;
-       end_user_pfn = memparse(p, &p);
-       end_user_pfn >>= PAGE_SHIFT;    
-       return 0;
-} 
-early_param("mem", parse_memopt);
-
-static int userdef __initdata;
-
-static int __init parse_memmap_opt(char *p)
-{
-       char *oldp;
-       unsigned long long start_at, mem_size;
-
-       if (!strcmp(p, "exactmap")) {
-#ifdef CONFIG_CRASH_DUMP
-               /* If we are doing a crash dump, we
-                * still need to know the real mem
-                * size before original memory map is
-                * reset.
-                */
-               e820_register_active_regions(0, 0, -1UL);
-               saved_max_pfn = e820_end_of_ram();
-               remove_all_active_ranges();
-#endif
-               end_pfn_map = 0;
-               e820.nr_map = 0;
-               userdef = 1;
-               return 0;
-       }
-
-       oldp = p;
-       mem_size = memparse(p, &p);
-       if (p == oldp)
-               return -EINVAL;
-       if (*p == '@') {
-               start_at = memparse(p+1, &p);
-               add_memory_region(start_at, mem_size, E820_RAM);
-       } else if (*p == '#') {
-               start_at = memparse(p+1, &p);
-               add_memory_region(start_at, mem_size, E820_ACPI);
-       } else if (*p == '$') {
-               start_at = memparse(p+1, &p);
-               add_memory_region(start_at, mem_size, E820_RESERVED);
-       } else {
-               end_user_pfn = (mem_size >> PAGE_SHIFT);
-       }
-       return *p == '\0' ? 0 : -EINVAL;
-}
-early_param("memmap", parse_memmap_opt);
-
-void __init finish_e820_parsing(void)
-{
-       if (userdef) {
-               printk(KERN_INFO "user-defined physical RAM map:\n");
-               e820_print_map("user");
-       }
-}
-
-unsigned long pci_mem_start = 0xaeedbabe;
-EXPORT_SYMBOL(pci_mem_start);
-
-/*
- * 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(void)
-{
-       unsigned long gapstart, gapsize, round;
-       unsigned long last;
-       int i;
-       int found = 0;
-
-       last = 0x100000000ull;
-       gapstart = 0x10000000;
-       gapsize = 0x400000;
-       i = e820.nr_map;
-       while (--i >= 0) {
-               unsigned long long start = e820.map[i].addr;
-               unsigned long long end = start + e820.map[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);
-}
diff --git a/arch/x86_64/kernel/e820_64.c b/arch/x86_64/kernel/e820_64.c
new file mode 100644 (file)
index 0000000..0f4d5e2
--- /dev/null
@@ -0,0 +1,725 @@
+/* 
+ * Handle the memory map.
+ * The functions here do the job until bootmem takes over.
+ *
+ *  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/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 <linux/mm.h>
+#include <linux/suspend.h>
+#include <linux/pfn.h>
+
+#include <asm/pgtable.h>
+#include <asm/page.h>
+#include <asm/e820.h>
+#include <asm/proto.h>
+#include <asm/bootsetup.h>
+#include <asm/sections.h>
+
+struct e820map e820;
+
+/* 
+ * 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.
+ */
+static unsigned long __initdata 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; 
+
+       /* various gunk below that needed for SMP startup */
+       if (addr < 0x8000) { 
+               *addrp = PAGE_ALIGN(0x8000);
+               return 1; 
+       }
+
+       /* direct mapping tables of the kernel */
+       if (last >= table_start<<PAGE_SHIFT && addr < table_end<<PAGE_SHIFT) { 
+               *addrp = PAGE_ALIGN(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 = PAGE_ALIGN(INITRD_START + INITRD_SIZE);
+               return 1;
+       } 
+#endif
+       /* kernel code */
+       if (last >= __pa_symbol(&_text) && addr < __pa_symbol(&_end)) {
+               *addrp = PAGE_ALIGN(__pa_symbol(&_end));
+               return 1;
+       }
+
+       if (last >= ebda_addr && addr < ebda_addr + ebda_size) {
+               *addrp = PAGE_ALIGN(ebda_addr + ebda_size);
+               return 1;
+       }
+
+#ifdef CONFIG_NUMA
+       /* NUMA memory to node map */
+       if (last >= nodemap_addr && addr < nodemap_addr + nodemap_size) {
+               *addrp = nodemap_addr + nodemap_size;
+               return 1;
+       }
+#endif
+       /* XXX ramdisk image here? */ 
+       return 0;
+} 
+
+/*
+ * This function checks if any part of the range <start,end> is mapped
+ * with type.
+ */
+int
+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;
+}
+EXPORT_SYMBOL_GPL(e820_any_mapped);
+
+/*
+ * 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 = PAGE_ALIGN(addr) + size;
+               if (last > ei->addr + ei->size)
+                       continue;
+               if (last > end) 
+                       continue;
+               return addr; 
+       } 
+       return -1UL;            
+} 
+
+/*
+ * Find the highest page frame number we have available
+ */
+unsigned long __init e820_end_of_ram(void)
+{
+       unsigned long end_pfn = 0;
+       end_pfn = find_max_pfn_with_active_regions();
+       
+       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; 
+
+       printk("end_pfn_map = %lu\n", end_pfn_map);
+       return end_pfn; 
+}
+
+/*
+ * Mark e820 reserved areas as busy for the resource manager.
+ */
+void __init e820_reserve_resources(void)
+{
+       int i;
+       for (i = 0; i < e820.nr_map; i++) {
+               struct resource *res;
+               res = alloc_bootmem_low(sizeof(struct resource));
+               switch (e820.map[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.map[i].addr;
+               res->end = res->start + e820.map[i].size - 1;
+               res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+               request_resource(&iomem_resource, res);
+               if (e820.map[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
+               }
+       }
+}
+
+/*
+ * Find the ranges of physical addresses that do not correspond to
+ * e820 RAM areas and mark the corresponding pages as nosave for software
+ * suspend and suspend to RAM.
+ *
+ * This function requires the e820 map to be sorted and without any
+ * overlapping entries and assumes the first e820 area to be RAM.
+ */
+void __init e820_mark_nosave_regions(void)
+{
+       int i;
+       unsigned long paddr;
+
+       paddr = round_down(e820.map[0].addr + e820.map[0].size, PAGE_SIZE);
+       for (i = 1; i < e820.nr_map; i++) {
+               struct e820entry *ei = &e820.map[i];
+
+               if (paddr < ei->addr)
+                       register_nosave_region(PFN_DOWN(paddr),
+                                               PFN_UP(ei->addr));
+
+               paddr = round_down(ei->addr + ei->size, PAGE_SIZE);
+               if (ei->type != E820_RAM)
+                       register_nosave_region(PFN_UP(ei->addr),
+                                               PFN_DOWN(paddr));
+
+               if (paddr >= (end_pfn << PAGE_SHIFT))
+                       break;
+       }
+}
+
+/*
+ * Finds an active region in the address range from start_pfn to end_pfn and
+ * returns its range in ei_startpfn and ei_endpfn for the e820 entry.
+ */
+static int __init e820_find_active_region(const struct e820entry *ei,
+                                         unsigned long start_pfn,
+                                         unsigned long end_pfn,
+                                         unsigned long *ei_startpfn,
+                                         unsigned long *ei_endpfn)
+{
+       *ei_startpfn = round_up(ei->addr, PAGE_SIZE) >> PAGE_SHIFT;
+       *ei_endpfn = round_down(ei->addr + ei->size, PAGE_SIZE) >> PAGE_SHIFT;
+
+       /* Skip map entries smaller than a page */
+       if (*ei_startpfn >= *ei_endpfn)
+               return 0;
+
+       /* Check if end_pfn_map should be updated */
+       if (ei->type != E820_RAM && *ei_endpfn > end_pfn_map)
+               end_pfn_map = *ei_endpfn;
+
+       /* Skip if map is outside the node */
+       if (ei->type != E820_RAM || *ei_endpfn <= start_pfn ||
+                                   *ei_startpfn >= end_pfn)
+               return 0;
+
+       /* Check for overlaps */
+       if (*ei_startpfn < start_pfn)
+               *ei_startpfn = start_pfn;
+       if (*ei_endpfn > end_pfn)
+               *ei_endpfn = end_pfn;
+
+       /* Obey end_user_pfn to save on memmap */
+       if (*ei_startpfn >= end_user_pfn)
+               return 0;
+       if (*ei_endpfn > end_user_pfn)
+               *ei_endpfn = end_user_pfn;
+
+       return 1;
+}
+
+/* Walk the e820 map and register active regions within a node */
+void __init
+e820_register_active_regions(int nid, unsigned long start_pfn,
+                                                       unsigned long end_pfn)
+{
+       unsigned long ei_startpfn;
+       unsigned long ei_endpfn;
+       int i;
+
+       for (i = 0; i < e820.nr_map; i++)
+               if (e820_find_active_region(&e820.map[i],
+                                           start_pfn, end_pfn,
+                                           &ei_startpfn, &ei_endpfn))
+                       add_active_range(nid, ei_startpfn, ei_endpfn);
+}
+
+/* 
+ * 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++;
+}
+
+/*
+ * Find the hole size (in bytes) in the memory range.
+ * @start: starting address of the memory range to scan
+ * @end: ending address of the memory range to scan
+ */
+unsigned long __init e820_hole_size(unsigned long start, unsigned long end)
+{
+       unsigned long start_pfn = start >> PAGE_SHIFT;
+       unsigned long end_pfn = end >> PAGE_SHIFT;
+       unsigned long ei_startpfn;
+       unsigned long ei_endpfn;
+       unsigned long ram = 0;
+       int i;
+
+       for (i = 0; i < e820.nr_map; i++) {
+               if (e820_find_active_region(&e820.map[i],
+                                           start_pfn, end_pfn,
+                                           &ei_startpfn, &ei_endpfn))
+                       ram += ei_endpfn - ei_startpfn;
+       }
+       return end - start - (ram << PAGE_SHIFT);
+}
+
+void __init e820_print_map(char *who)
+{
+       int i;
+
+       for (i = 0; i < e820.nr_map; i++) {
+               printk(KERN_INFO " %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.
+ */
+static int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
+{
+       /* Only one memory region (or negative)? Ignore it */
+       if (nr_map < 2)
+               return -1;
+
+       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;
+
+               add_memory_region(start, size, type);
+       } while (biosmap++,--nr_map);
+       return 0;
+}
+
+void early_panic(char *msg)
+{
+       early_printk(msg);
+       panic(msg);
+}
+
+void __init setup_memory_region(void)
+{
+       /*
+        * 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)
+               early_panic("Cannot find a valid memory map");
+       printk(KERN_INFO "BIOS-provided physical RAM map:\n");
+       e820_print_map("BIOS-e820");
+}
+
+static int __init parse_memopt(char *p)
+{
+       if (!p)
+               return -EINVAL;
+       end_user_pfn = memparse(p, &p);
+       end_user_pfn >>= PAGE_SHIFT;    
+       return 0;
+} 
+early_param("mem", parse_memopt);
+
+static int userdef __initdata;
+
+static int __init parse_memmap_opt(char *p)
+{
+       char *oldp;
+       unsigned long long start_at, mem_size;
+
+       if (!strcmp(p, "exactmap")) {
+#ifdef CONFIG_CRASH_DUMP
+               /* If we are doing a crash dump, we
+                * still need to know the real mem
+                * size before original memory map is
+                * reset.
+                */
+               e820_register_active_regions(0, 0, -1UL);
+               saved_max_pfn = e820_end_of_ram();
+               remove_all_active_ranges();
+#endif
+               end_pfn_map = 0;
+               e820.nr_map = 0;
+               userdef = 1;
+               return 0;
+       }
+
+       oldp = p;
+       mem_size = memparse(p, &p);
+       if (p == oldp)
+               return -EINVAL;
+       if (*p == '@') {
+               start_at = memparse(p+1, &p);
+               add_memory_region(start_at, mem_size, E820_RAM);
+       } else if (*p == '#') {
+               start_at = memparse(p+1, &p);
+               add_memory_region(start_at, mem_size, E820_ACPI);
+       } else if (*p == '$') {
+               start_at = memparse(p+1, &p);
+               add_memory_region(start_at, mem_size, E820_RESERVED);
+       } else {
+               end_user_pfn = (mem_size >> PAGE_SHIFT);
+       }
+       return *p == '\0' ? 0 : -EINVAL;
+}
+early_param("memmap", parse_memmap_opt);
+
+void __init finish_e820_parsing(void)
+{
+       if (userdef) {
+               printk(KERN_INFO "user-defined physical RAM map:\n");
+               e820_print_map("user");
+       }
+}
+
+unsigned long pci_mem_start = 0xaeedbabe;
+EXPORT_SYMBOL(pci_mem_start);
+
+/*
+ * 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(void)
+{
+       unsigned long gapstart, gapsize, round;
+       unsigned long last;
+       int i;
+       int found = 0;
+
+       last = 0x100000000ull;
+       gapstart = 0x10000000;
+       gapsize = 0x400000;
+       i = e820.nr_map;
+       while (--i >= 0) {
+               unsigned long long start = e820.map[i].addr;
+               unsigned long long end = start + e820.map[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);
+}