On 07/25/2012 04:24 PM, Stefan Bader wrote: >>> ... >>> ifdef CONFIG_X86_32 >>> /* >>> * Don't use a large page for the first 2/4MB of memory >>> * because there are often fixed size MTRRs in there >>> * and overlapping MTRRs into large pages can cause >>> * slowdowns. >>> */ >>> >> >> That's equally true for X86_64. >> >> Best would be to merge the MTRRs into PAT, but that might not work for SMM. >> >> > Ok, true. Not sure why this was restricted to 32bit when reconsidering. Except > if in 64bit it was assumed (or asserted) that the regions are aligned to 2M... > But maybe this can be answered by someone knowing the details. I would not > mind > either way (have the first range with 4K pages in all cases or fixing the > additional PTE allocation). Just as it is now it is inconsistent.
Sometimes CONFIG_X86_32 is used as an alias for "machines so old they don't support x86_64". As a 32-bit kernel can be run on a machine that does support x86_64, it should be replaced by a runtime test for X86_FEATURE_LM, until a more accurate test can be found. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
