> 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. Generally speaking, It seems no good idea. desktop and server world don't interest arch specific mmu attribute crap. because many many opensource and ISV library don't care it. I know highend hpc and embedded have differenct eco-system. they might want to use such strange mmu feature. I recommend to you are focusing popwerpc eco-system. I'm not against changing kernel internal. I only disagree mmu attribute fashion will be become used widely. > > 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 :-) -- 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>