On Mon, 28 Sep 2015, Dave Hansen wrote: > From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > Previous documentation has referred to these 4 bits as "ignored". > That means that software could have made use of them. But, as > far as I know, the kernel never used them. > > They are still ignored when protection keys is not enabled, so > they could theoretically still get used for software purposes. > > We also implement "empty" versions so that code that references > to them can be optimized away by the compiler when the config > option is not enabled. > > Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> -- 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>