diff options
Diffstat (limited to 'arch/x86/mm/ioremap.c')
| -rw-r--r-- | arch/x86/mm/ioremap.c | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 9f42d7e9c158..f4c95aec5acb 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -42,6 +42,22 @@ int page_is_ram(unsigned long pagenr) unsigned long addr, end; int i; + /* + * A special case is the first 4Kb of memory; + * This is a BIOS owned area, not kernel ram, but generally + * not listed as such in the E820 table. + */ + if (pagenr == 0) + return 0; + + /* + * Second special case: Some BIOSen report the PC BIOS + * area (640->1Mb) as ram even though it is not. + */ + if (pagenr >= (BIOS_BEGIN >> PAGE_SHIFT) && + pagenr < (BIOS_END >> PAGE_SHIFT)) + return 0; + for (i = 0; i < e820.nr_map; i++) { /* * Not usable memory: @@ -51,14 +67,6 @@ int page_is_ram(unsigned long pagenr) addr = (e820.map[i].addr + PAGE_SIZE-1) >> PAGE_SHIFT; end = (e820.map[i].addr + e820.map[i].size) >> PAGE_SHIFT; - /* - * Sanity check: Some BIOSen report areas as RAM that - * are not. Notably the 640->1Mb area, which is the - * PCI BIOS area. - */ - if (addr >= (BIOS_BEGIN >> PAGE_SHIFT) && - end < (BIOS_END >> PAGE_SHIFT)) - continue; if ((pagenr >= addr) && (pagenr < end)) return 1; |