diff options
Diffstat (limited to 'arch/x86/mm/init.c')
| -rw-r--r-- | arch/x86/mm/init.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index ce6a722587d8..f89df52683c5 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -1,9 +1,33 @@ +#include <linux/ioport.h> #include <linux/swap.h> + #include <asm/cacheflush.h> #include <asm/page.h> +#include <asm/page_types.h> #include <asm/sections.h> #include <asm/system.h> +/* + * 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, 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 (iomem_is_exclusive(pagenr << PAGE_SHIFT)) + return 0; + if (!page_is_ram(pagenr)) + return 1; + return 0; +} + void free_init_pages(char *what, unsigned long begin, unsigned long end) { unsigned long addr = begin; |
