This commit was manufactured by cvs2svn to create branch 'vserver'.
[linux-2.6.git] / arch / i386 / kernel / e820.c
diff --git a/arch/i386/kernel/e820.c b/arch/i386/kernel/e820.c
new file mode 100644 (file)
index 0000000..c18ad69
--- /dev/null
@@ -0,0 +1,976 @@
+#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/efi.h>
+#include <linux/pfn.h>
+#include <linux/uaccess.h>
+
+#include <asm/pgtable.h>
+#include <asm/page.h>
+#include <asm/e820.h>
+
+#ifdef CONFIG_XEN
+#include <asm/hypervisor.h>
+#include <xen/interface/physdev.h>
+#include <xen/interface/memory.h>
+#include <xen/features.h>
+#include <xen/xencons.h>
+#endif
+
+#ifdef CONFIG_EFI
+int efi_enabled = 0;
+EXPORT_SYMBOL(efi_enabled);
+#endif
+
+#ifdef CONFIG_XEN
+struct e820map machine_e820;
+#endif
+static void __init
+e820_setup_gap(struct e820entry *e820, int nr_map);
+
+struct e820map e820;
+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;
+/* For PCI or other memory-mapped resources */
+unsigned long pci_mem_start = 0x10000000;
+#ifdef CONFIG_PCI
+EXPORT_SYMBOL(pci_mem_start);
+#endif
+extern int user_defined_memmap;
+struct resource data_resource = {
+       .name   = "Kernel data",
+       .start  = 0,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
+};
+
+struct resource code_resource = {
+       .name   = "Kernel code",
+       .start  = 0,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
+};
+
+static struct resource system_rom_resource = {
+       .name   = "System ROM",
+       .start  = 0xf0000,
+       .end    = 0xfffff,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+};
+
+static struct resource extension_rom_resource = {
+       .name   = "Extension ROM",
+       .start  = 0xe0000,
+       .end    = 0xeffff,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+};
+
+static struct resource adapter_rom_resources[] = { {
+       .name   = "Adapter ROM",
+       .start  = 0xc8000,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+       .name   = "Adapter ROM",
+       .start  = 0,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+       .name   = "Adapter ROM",
+       .start  = 0,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+       .name   = "Adapter ROM",
+       .start  = 0,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+       .name   = "Adapter ROM",
+       .start  = 0,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+}, {
+       .name   = "Adapter ROM",
+       .start  = 0,
+       .end    = 0,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+} };
+
+static struct resource video_rom_resource = {
+       .name   = "Video ROM",
+       .start  = 0xc0000,
+       .end    = 0xc7fff,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
+};
+
+static struct resource video_ram_resource = {
+       .name   = "Video RAM area",
+       .start  = 0xa0000,
+       .end    = 0xbffff,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
+};
+
+static struct resource standard_io_resources[] = { {
+       .name   = "dma1",
+       .start  = 0x0000,
+       .end    = 0x001f,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "pic1",
+       .start  = 0x0020,
+       .end    = 0x0021,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "timer0",
+       .start  = 0x0040,
+       .end    = 0x0043,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "timer1",
+       .start  = 0x0050,
+       .end    = 0x0053,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "keyboard",
+       .start  = 0x0060,
+       .end    = 0x006f,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "dma page reg",
+       .start  = 0x0080,
+       .end    = 0x008f,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "pic2",
+       .start  = 0x00a0,
+       .end    = 0x00a1,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "dma2",
+       .start  = 0x00c0,
+       .end    = 0x00df,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+}, {
+       .name   = "fpu",
+       .start  = 0x00f0,
+       .end    = 0x00ff,
+       .flags  = IORESOURCE_BUSY | IORESOURCE_IO
+} };
+
+static int romsignature(const unsigned char *x)
+{
+       unsigned short sig;
+       int ret = 0;
+       if (probe_kernel_address((const unsigned short *)x, sig) == 0)
+               ret = (sig == 0xaa55);
+       return ret;
+}
+
+static int __init romchecksum(unsigned char *rom, unsigned long length)
+{
+       unsigned char *p, sum = 0;
+
+       for (p = rom; p < rom + length; p++)
+               sum += *p;
+       return sum == 0;
+}
+
+static void __init probe_roms(void)
+{
+       unsigned long start, length, upper;
+       unsigned char *rom;
+       int           i;
+
+#ifdef CONFIG_XEN
+       /* Nothing to do if not running in dom0. */
+       if (!is_initial_xendomain())
+               return;
+#endif
+
+       /* video rom */
+       upper = adapter_rom_resources[0].start;
+       for (start = video_rom_resource.start; start < upper; start += 2048) {
+               rom = isa_bus_to_virt(start);
+               if (!romsignature(rom))
+                       continue;
+
+               video_rom_resource.start = start;
+
+               /* 0 < length <= 0x7f * 512, historically */
+               length = rom[2] * 512;
+
+               /* if checksum okay, trust length byte */
+               if (length && romchecksum(rom, length))
+                       video_rom_resource.end = start + length - 1;
+
+               request_resource(&iomem_resource, &video_rom_resource);
+               break;
+       }
+
+       start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
+       if (start < upper)
+               start = upper;
+
+       /* system rom */
+       request_resource(&iomem_resource, &system_rom_resource);
+       upper = system_rom_resource.start;
+
+       /* check for extension rom (ignore length byte!) */
+       rom = isa_bus_to_virt(extension_rom_resource.start);
+       if (romsignature(rom)) {
+               length = extension_rom_resource.end - extension_rom_resource.start + 1;
+               if (romchecksum(rom, length)) {
+                       request_resource(&iomem_resource, &extension_rom_resource);
+                       upper = extension_rom_resource.start;
+               }
+       }
+
+       /* check for adapter roms on 2k boundaries */
+       for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
+               rom = isa_bus_to_virt(start);
+               if (!romsignature(rom))
+                       continue;
+
+               /* 0 < length <= 0x7f * 512, historically */
+               length = rom[2] * 512;
+
+               /* but accept any length that fits if checksum okay */
+               if (!length || start + length > upper || !romchecksum(rom, length))
+                       continue;
+
+               adapter_rom_resources[i].start = start;
+               adapter_rom_resources[i].end = start + length - 1;
+               request_resource(&iomem_resource, &adapter_rom_resources[i]);
+
+               start = adapter_rom_resources[i++].end & ~2047UL;
+       }
+}
+
+/*
+ * Request address space for all standard RAM and ROM resources
+ * and also for regions reported as reserved by the e820.
+ */
+static void __init
+legacy_init_iomem_resources(struct resource *code_resource, struct resource *data_resource)
+{
+       int i;
+       struct e820entry *map = e820.map;
+       int nr_map = e820.nr_map;
+#ifdef CONFIG_XEN_PRIVILEGED_GUEST
+       struct xen_memory_map memmap;
+
+       map = machine_e820.map;
+       memmap.nr_entries = E820MAX;
+
+       set_xen_guest_handle(memmap.buffer, map);
+
+       if(HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap))
+               BUG();
+       machine_e820.nr_map = memmap.nr_entries;
+       nr_map = memmap.nr_entries;
+       e820_setup_gap(map, memmap.nr_entries);
+#endif
+
+       probe_roms();
+       for (i = 0; i < nr_map; i++) {
+               struct resource *res;
+#ifndef CONFIG_RESOURCES_64BIT
+               if (map[i].addr + map[i].size > 0x100000000ULL)
+                       continue;
+#endif
+               res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
+               switch (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 = map[i].addr;
+               res->end = res->start + map[i].size - 1;
+               res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+               if (request_resource(&iomem_resource, res)) {
+                       kfree(res);
+                       continue;
+               }
+               if (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.
+                        */
+#ifndef CONFIG_XEN
+                       request_resource(res, code_resource);
+                       request_resource(res, data_resource);
+#endif
+#ifdef CONFIG_KEXEC
+                       request_resource(res, &crashk_res);
+#endif
+               }
+       }
+}
+
+/*
+ * Request address space for all standard resources
+ *
+ * This is called just before pcibios_init(), which is also a
+ * subsys_initcall, but is linked in later (in arch/i386/pci/common.c).
+ */
+static int __init request_standard_resources(void)
+{
+       int i;
+
+       printk("Setting up standard PCI resources\n");
+#ifdef CONFIG_XEN
+       /* Nothing to do if not running in dom0. */
+       if (!is_initial_xendomain())
+               return 0;
+#endif
+       if (efi_enabled)
+               efi_initialize_iomem_resources(&code_resource, &data_resource);
+       else
+               legacy_init_iomem_resources(&code_resource, &data_resource);
+
+       /* EFI systems may still have VGA */
+       request_resource(&iomem_resource, &video_ram_resource);
+
+       /* request I/O space for devices used on all i[345]86 PCs */
+       for (i = 0; i < ARRAY_SIZE(standard_io_resources); i++)
+               request_resource(&ioport_resource, &standard_io_resources[i]);
+       return 0;
+}
+
+subsys_initcall(request_standard_resources);
+
+void __init add_memory_region(unsigned long long start,
+                             unsigned long long size, int type)
+{
+       int x;
+
+       if (!efi_enabled) {
+                       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++;
+       }
+} /* add_memory_region */
+
+/*
+ * Sanitize the BIOS e820 map.
+ *
+ * Some e820 responses include overlapping entries.  The following
+ * replaces the original e820 map with a new one, removing overlaps.
+ *
+ */
+int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
+{
+       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_
+       */
+       printk("sanitize start\n");
+       /* if there's only one memory region, don't bother */
+       if (*pnr_map < 2) {
+               printk("sanitize bail 0\n");
+               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) {
+                       printk("sanitize bail 1\n");
+                       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;        /* true number of change-points */
+
+       /* 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;
+
+       printk("sanitize end\n");
+       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.)
+ */
+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 long start = biosmap->addr;
+               unsigned long long size = biosmap->size;
+               unsigned long long end = start + size;
+               unsigned long type = biosmap->type;
+               printk("copy_e820_map() start: %016Lx size: %016Lx end: %016Lx type: %ld\n", start, size, end, 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.
+                */
+               if (type == E820_RAM) {
+                       printk("copy_e820_map() type is E820_RAM\n");
+                       if (start < 0x100000ULL && end > 0xA0000ULL) {
+                               printk("copy_e820_map() lies in range...\n");
+                               if (start < 0xA0000ULL) {
+                                       printk("copy_e820_map() start < 0xA0000ULL\n");
+                                       add_memory_region(start, 0xA0000ULL-start, type);
+                               }
+                               if (end <= 0x100000ULL) {
+                                       printk("copy_e820_map() end <= 0x100000ULL\n");
+                                       continue;
+                               }
+                               start = 0x100000ULL;
+                               size = end - start;
+                       }
+               }
+#endif
+               add_memory_region(start, size, type);
+       } while (biosmap++,--nr_map);
+       return 0;
+}
+
+/*
+ * Callback for efi_memory_walk.
+ */
+static int __init
+efi_find_max_pfn(unsigned long start, unsigned long end, void *arg)
+{
+       unsigned long *max_pfn = arg, pfn;
+
+       if (start < end) {
+               pfn = PFN_UP(end -1);
+               if (pfn > *max_pfn)
+                       *max_pfn = pfn;
+       }
+       return 0;
+}
+
+static int __init
+efi_memory_present_wrapper(unsigned long start, unsigned long end, void *arg)
+{
+       memory_present(0, PFN_UP(start), PFN_DOWN(end));
+       return 0;
+}
+
+/*
+ * Find the highest page frame number we have available
+ */
+void __init find_max_pfn(void)
+{
+       int i;
+
+       max_pfn = 0;
+       if (efi_enabled) {
+               efi_memmap_walk(efi_find_max_pfn, &max_pfn);
+               efi_memmap_walk(efi_memory_present_wrapper, NULL);
+               return;
+       }
+
+       for (i = 0; i < e820.nr_map; i++) {
+               unsigned long start, end;
+               /* RAM? */
+               if (e820.map[i].type != E820_RAM)
+                       continue;
+               start = PFN_UP(e820.map[i].addr);
+               end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
+               if (start >= end)
+                       continue;
+               if (end > max_pfn)
+                       max_pfn = end;
+               memory_present(0, start, end);
+       }
+}
+
+/*
+ * Free all available memory for boot time allocation.  Used
+ * as a callback function by efi_memory_walk()
+ */
+
+static int __init
+free_available_memory(unsigned long start, unsigned long end, void *arg)
+{
+       /* check max_low_pfn */
+       if (start >= (max_low_pfn << PAGE_SHIFT))
+               return 0;
+       if (end >= (max_low_pfn << PAGE_SHIFT))
+               end = max_low_pfn << PAGE_SHIFT;
+       if (start < end)
+               free_bootmem(start, end - start);
+
+       return 0;
+}
+/*
+ * Register fully available low RAM pages with the bootmem allocator.
+ */
+void __init register_bootmem_low_pages(unsigned long max_low_pfn)
+{
+       int i;
+
+       if (efi_enabled) {
+               efi_memmap_walk(free_available_memory, NULL);
+               return;
+       }
+       for (i = 0; i < e820.nr_map; i++) {
+               unsigned long curr_pfn, last_pfn, size;
+               /*
+                * Reserve usable low memory
+                */
+               if (e820.map[i].type != E820_RAM)
+                       continue;
+               /*
+                * We are rounding up the start address of usable memory:
+                */
+               curr_pfn = PFN_UP(e820.map[i].addr);
+               if (curr_pfn >= max_low_pfn)
+                       continue;
+               /*
+                * ... and at the end of the usable range downwards:
+                */
+               last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
+
+#ifdef CONFIG_XEN
+               /*
+                 * Truncate to the number of actual pages currently
+                 * present.
+                 */
+               if (last_pfn > xen_start_info->nr_pages)
+                       last_pfn = xen_start_info->nr_pages;
+#endif
+
+               if (last_pfn > max_low_pfn)
+                       last_pfn = max_low_pfn;
+
+               /*
+                * .. finally, did all the rounding and playing
+                * around just make the area go away?
+                */
+               if (last_pfn <= curr_pfn)
+                       continue;
+
+               size = last_pfn - curr_pfn;
+               free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
+       }
+}
+
+/*
+ * Locate a unused range of the physical address space below 4G which
+ * can be used for PCI mappings.
+ */
+static void __init
+e820_setup_gap(struct e820entry *e820, int nr_map)
+{
+       unsigned long gapstart, gapsize, round;
+       unsigned long long last;
+       int i;
+
+       /*
+        * Search for the bigest gap in the low 32 bits of the e820
+        * memory space.
+        */
+       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;
+                       }
+               }
+               if (start < last)
+                       last = start;
+       }
+
+       /*
+        * 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("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
+               pci_mem_start, gapstart, gapsize);
+}
+
+void __init e820_register_memory(void)
+{
+#ifndef CONFIG_XEN
+       e820_setup_gap(e820.map, e820.nr_map);
+#endif
+}
+
+void __init print_memory_map(char *who)
+{
+       int i;
+
+       for (i = 0; i < e820.nr_map; i++) {
+               printk(" %s: %016Lx - %016Lx ", who,
+                       e820.map[i].addr,
+                       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 %lu\n", e820.map[i].type);
+                               break;
+               }
+       }
+}
+
+static __init __always_inline void efi_limit_regions(unsigned long long size)
+{
+       unsigned long long current_addr = 0;
+       efi_memory_desc_t *md, *next_md;
+       void *p, *p1;
+       int i, j;
+
+       j = 0;
+       p1 = memmap.map;
+       for (p = p1, i = 0; p < memmap.map_end; p += memmap.desc_size, i++) {
+               md = p;
+               next_md = p1;
+               current_addr = md->phys_addr +
+                       PFN_PHYS(md->num_pages);
+               if (is_available_memory(md)) {
+                       if (md->phys_addr >= size) continue;
+                       memcpy(next_md, md, memmap.desc_size);
+                       if (current_addr >= size) {
+                               next_md->num_pages -=
+                                       PFN_UP(current_addr-size);
+                       }
+                       p1 += memmap.desc_size;
+                       next_md = p1;
+                       j++;
+               } else if ((md->attribute & EFI_MEMORY_RUNTIME) ==
+                          EFI_MEMORY_RUNTIME) {
+                       /* In order to make runtime services
+                        * available we have to include runtime
+                        * memory regions in memory map */
+                       memcpy(next_md, md, memmap.desc_size);
+                       p1 += memmap.desc_size;
+                       next_md = p1;
+                       j++;
+               }
+       }
+       memmap.nr_map = j;
+       memmap.map_end = memmap.map +
+               (memmap.nr_map * memmap.desc_size);
+}
+
+void __init limit_regions(unsigned long long size)
+{
+       unsigned long long current_addr = 0;
+       int i;
+
+       print_memory_map("limit_regions start");
+       if (efi_enabled) {
+               efi_limit_regions(size);
+               return;
+       }
+       for (i = 0; i < e820.nr_map; i++) {
+               current_addr = e820.map[i].addr + e820.map[i].size;
+               if (current_addr < size)
+                       continue;
+
+               if (e820.map[i].type != E820_RAM)
+                       continue;
+
+               if (e820.map[i].addr >= size) {
+                       /*
+                        * This region starts past the end of the
+                        * requested size, skip it completely.
+                        */
+                       e820.nr_map = i;
+               } else {
+                       e820.nr_map = i + 1;
+                       e820.map[i].size -= current_addr - size;
+               }
+               print_memory_map("limit_regions endfor");
+               return;
+       }
+#ifdef CONFIG_XEN
+       if (i==e820.nr_map && current_addr < size) {
+               /*
+                 * The e820 map finished before our requested size so
+                 * extend the final entry to the requested address.
+                 */
+               --i;
+               if (e820.map[i].type == E820_RAM)
+                       e820.map[i].size -= current_addr - size;
+               else
+                       add_memory_region(current_addr, size - current_addr, E820_RAM);
+       }
+#endif
+       print_memory_map("limit_regions endfunc");
+}
+
+ /*
+  * 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 s, unsigned long e, unsigned type)
+{
+       u64 start = s;
+       u64 end = e;
+       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;
+}
+
+static int __init parse_memmap(char *arg)
+{
+       if (!arg)
+               return -EINVAL;
+
+       if (strcmp(arg, "exactmap") == 0) {
+#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.
+                */
+               find_max_pfn();
+               saved_max_pfn = max_pfn;
+#endif
+               e820.nr_map = 0;
+               user_defined_memmap = 1;
+       } else {
+               /* If the user specifies memory size, we
+                * limit the BIOS-provided memory map to
+                * that size. exactmap can be used to specify
+                * the exact map. mem=number can be used to
+                * trim the existing memory map.
+                */
+               unsigned long long start_at, mem_size;
+
+               mem_size = memparse(arg, &arg);
+               if (*arg == '@') {
+                       start_at = memparse(arg+1, &arg);
+                       add_memory_region(start_at, mem_size, E820_RAM);
+               } else if (*arg == '#') {
+                       start_at = memparse(arg+1, &arg);
+                       add_memory_region(start_at, mem_size, E820_ACPI);
+               } else if (*arg == '$') {
+                       start_at = memparse(arg+1, &arg);
+                       add_memory_region(start_at, mem_size, E820_RESERVED);
+               } else {
+                       limit_regions(mem_size);
+                       user_defined_memmap = 1;
+               }
+       }
+       return 0;
+}
+early_param("memmap", parse_memmap);