On Mon, 2014-07-21 at 09:47 -0700, H. Peter Anvin wrote: > On 07/21/2014 09:31 AM, Toshi Kani wrote: > > Do you have any comments / suggestions for this approach? > > Approach to what, specifically? > > Keep in mind the PAT bit is different for large pages. This needs to be > dealt with. You are right. I was under a wrong impression that __change_page_attr() always splits a large pages into 4KB pages, but I overlooked the fact that it can handle a large page as well. So, this approach does not work... > I would also like a systematic way to deal with the fact > that Xen (sigh) is stuck with a separate mapping system. > > I guess Linux could adopt the Xen mappings if that makes it easier, as > long as that doesn't have a negative impact on native hardware -- we can > possibly deal with some older chips not being optimal. I see. I agree that supporting the PAT bit is the right direction, but I do not know how much effort we need. I will study on this. > However, my thinking has been to have a "reverse PAT" table in memory of memory > types to encodings, both for regular and large pages. I am not clear about your idea of the "reverse PAT" table. Would you care to elaborate? How is it different from using pte_val() being a paravirt function on Xen? Thanks, -Toshi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>