Merge to Fedora Core 2 kernel-2.6.8-1.521

[linux-2.6.git] / arch / x86_64 / mm / init.c

diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 75825f0..a51772d 100644 (file)
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -374,7 +374,7 @@ void __init clear_kernel_mapping(unsigned long address, unsigned long size)
        __flush_tlb_all();
 } 
 
-int page_is_ram (unsigned long pagenr)
+static inline int page_is_ram (unsigned long pagenr)
 {
        int i;
 
@@ -396,6 +396,26 @@ int page_is_ram (unsigned long pagenr)
        return 0;
 }
 
+/*
+ * devmem_is_allowed() checks to see if /dev/mem access to a certain address is
+ * valid. The argument is a physical page number.
+ *
+ *
+ * On x86-64, access has to be given to the first megabyte of ram because that area
+ * contains bios code and data regions used by X and dosemu and similar apps.
+ * Access has to be given to non-kernel-ram areas as well, these contain the PCI
+ * mmio resources as well as potential bios/acpi data regions.
+ */
+int devmem_is_allowed(unsigned long pagenr)
+{
+       if (pagenr <= 256)
+               return 1;
+       if (!page_is_ram(pagenr))
+               return 1;
+       return 0;
+}
+
+
 static struct kcore_list kcore_mem, kcore_vmalloc, kcore_kernel, kcore_modules,
                         kcore_vsyscall;