On Tue, 2010-04-06 at 19:26 +0900, KOSAKI Motohiro wrote: > > Ok, I see. No biggie. The main deal remains how we want to do that > > inside the kernel :-) I think the less horrible options here are > > to either extend vm_flags to always be 64-bit, or add a separate > > vm_map_attributes flag, and add the necessary bits and pieces to > > prevent merge accross different attribute vma's. > > vma->vm_flags already have VM_SAO. Why do we need more flags? > At least, I dislike to add separate flags member into vma. > It might introduce unnecessary messy into vma merge thing. Well, we did shove SAO in there, and used up the very last vm_flag for it a while back. Now I need another one, for little endian mappings. So I'm stuck. But the problem goes further I believe. Archs do nowadays have quite an interesting set of MMU attributes that it would be useful to expose to some extent. Some powerpc's also provide storage keys for example and I think ARM have something along those lines. There's interesting cachability attributes too, on x86 as well. Being able to use such attributes to request for example a relaxed ordering mapping on x86 might be useful. I think it basically boils down to either extend vm_flags to always be 64-bit, which seems to be Nick preferred approach, or introduct a vm_attributes with all the necessary changes to the merge code to take it into account (not -that- hard tho, there's only half a page of results in grep for these things :-) Cheers, Ben. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>