On Mon, 2015-03-16 at 21:24 +0000, Kani, Toshimitsu wrote: > > On Mar 16, 2015, at 3:58 AM, Ingo Molnar <mingo@xxxxxxxxxx> wrote: > >> * Toshi Kani <toshi.kani@xxxxxx> wrote: : > > >> + if (!(mtrr_state.have_fixed) || > >> + !(mtrr_state.enabled & MTRR_STATE_MTRR_FIXED_ENABLED)) > > > > Btw., can MTRR_STATE_MTRR_FIXED_ENABLED ever be set in > > mtrr_state.enabled, without mtrr_state.have_fixed being set? > > Yes, I believe the arch allows the fixed entries disabled > while MTRRs are enabled. I expect the most of systems > implement the fixed entries, though. Sorry, I noticed I had mis-read your question before... No, MTRR_STATE_MTRR_FIXED_ENABLED may not be set without mtrr_state.have_fixed being set. mtrr_state.have_fixed indicates if the CPU supports MTRR fixed ranges. So, they can be only enabled when the CPU has ones. > > AFAICS get_mtrr_state() will only ever fill in mtrr_state with fixed > > MTRRs if mtrr_state.have_fixed != 0 - but I might be mis-reading the > > (rather convoluted) flow of code ... > > I will check the code next week. Yes, you are right that get_mtrr_state() only fills in mtrr_state.fixed_ranges[] when mtrr_state.have_fixed is set. This is because the MSRs containing the fixed ranges are only valid when this flag is set. 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>