On Mon, Jan 14, 2008 at 05:43:24PM +0100, Ingo Molnar wrote: > > * Pallipadi, Venkatesh <[EMAIL PROTECTED]> wrote: > > > Also, relying on MTRR, is like giving more importance to BIOS writer > > than required :-). I think the best way to deal with MTRR is just to > > not touch it. Leave it as it is and do not try to assume that they are > > correct, as frequently they will not be. > > i'd suggest the following strategy on PAT-capable CPUs: > > - do not try to write MTRRs. Ever. > > - _read_ the current MTRR settings (including the default MTRR) and > check them against the e820 map. I can see two basic types of > mismatches: > > - RAM area marked fine in e820 but marked UC by MTRR: this > currently results in a slow system.
Time to resurrect Jesse's old patches i386-trim-memory-not-covered-by-wb-mtrrs.patch(which was in -mm sometime back) > (NOTE: UC- would be fine and > overridable by PAT, hence it's not a conflict we should detect.) UC- can't be specified by MTRR's. > - mmio area marked cacheable in the MTRR (results in broken system) PAT can help specify the UC/WC attribute here. thanks, suresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
