diff options
Diffstat (limited to 'arch/x86_64/kernel/e820.c')
| -rw-r--r-- | arch/x86_64/kernel/e820.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/e820.c b/arch/x86_64/kernel/e820.c index 6ded3a50dfe63..b548dea4e5b95 100644 --- a/arch/x86_64/kernel/e820.c +++ b/arch/x86_64/kernel/e820.c @@ -185,6 +185,40 @@ unsigned long __init e820_end_of_ram(void) } /* + * 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(void) |