warning when building with gcc -W : 

 include/linux/efi.h: In function `efi_range_is_wc':
 include/linux/efi.h:320: warning: comparison between signed and unsigned

It looks to me like a significantly large 'len' passed in could cause the 
loop to never end. Isn't it safer to make 'i' an unsigned long as well? 
Like this little patch below (which of course also kills the warning) :
Signed-off-by: NJesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: NTony Luck <tony.luck@intel.com>