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Date: Sat, 04 Oct 2008 17:46:24 -0700 From: "H. Peter Anvin" <hpa@...or.com> To: Yinghai Lu <yhlu.kernel@...il.com> CC: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>, Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCH 2/3] x86: mtrr_cleanup: first 1M should be coverred in var mtrrs Yinghai Lu wrote: > + /* > + * [0, 1M) should always be coverred by var mtrr with WB > + * and fixed mtrrs should take effective before var mtrr for it > + */ > + nr_range = add_range_with_merge(range, nr_range, 0, > + (1ULL<<(20 - PAGE_SHIFT)) - 1); > + /* sort the ranges */ > + sort(range, nr_range, sizeof(struct res_range), cmp_range, NULL); > + The first 1 MB is a total don't care for the variable MTRRs -- they don't have to be covered *or* uncovered, since the entire first 1 MB is addressed by fixed MTRRs. In practice, it is *likely* that you're going to want to merge it with a WB MTRR, but with various vendors doing all kinds of strange things on EFI-damaged platforms, it may not always be that way. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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