LXR linux/arch/x86/kernel/resource.c

   1#include <linux/ioport.h>
   2#include <asm/e820.h>
   3
   4static void resource_clip(struct resource *res, resource_size_t start,
   5                          resource_size_t end)
   6{
   7        resource_size_t low = 0, high = 0;
   8
   9        if (res->end < start || res->start > end)
  10                return;         /* no conflict */
  11
  12        if (res->start < start)
  13                low = start - res->start;
  14
  15        if (res->end > end)
  16                high = res->end - end;
  17
  18        /* Keep the area above or below the conflict, whichever is larger */
  19        if (low > high)
  20                res->end = start - 1;
  21        else
  22                res->start = end + 1;
  23}
  24
  25static void remove_e820_regions(struct resource *avail)
  26{
  27        int i;
  28        struct e820entry *entry;
  29
  30        for (i = 0; i < e820.nr_map; i++) {
  31                entry = &e820.map[i];
  32
  33                resource_clip(avail, entry->addr,
  34                              entry->addr + entry->size - 1);
  35        }
  36}
  37
  38void arch_remove_reservations(struct resource *avail)
  39{
  40        /* Trim out BIOS areas (low 1MB and high 2MB) and E820 regions */
  41        if (avail->flags & IORESOURCE_MEM) {
  42                if (avail->start < BIOS_END)
  43                        avail->start = BIOS_END;
  44                resource_clip(avail, BIOS_ROM_BASE, BIOS_ROM_END);
  45
  46                remove_e820_regions(avail);
  47        }
  48}
  49