On 09/10/2014 11:26 AM, Andy Lutomirski wrote: > On Wed, Sep 10, 2014 at 9:51 AM, Toshi Kani <toshi.kani@xxxxxx> wrote: >> This patch changes reserve_memtype() to handle the WT cache mode. >> When PAT is not enabled, it continues to set UC- to *new_type for >> any non-WB request. >> >> When a target range is RAM, reserve_ram_pages_type() fails for WT >> for now. This function may not reserve a RAM range for WT since >> reserve_ram_pages_type() uses the page flags limited to three memory >> types, WB, WC and UC. > > Should it fail if WT is unavailable due to errata? More generally, > how are all of the do_something_wc / do_something_wt / > do_something_nocache helpers supposed to handle unsupported types? > Errata, or because it is pre-PAT hardware. Keep in mind that even pre-PAT hardware supports using page tables for cache types, it is only that the only types supposed are WB, WT, UC. -hpa -- 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>