http://bugzilla.kernel.org/show_bug.cgi?id=11541
------- Comment #85 from [email protected] 2009-03-05 02:27 ------- Thanks for that debug data. This shows that, the mainline kernel w/o my patch (attachment #20412) is (potentially(*)) changing RdMem/WrMem bits on CPUs 1 and 2 from: [ 0.010000] MTRRfixed(268): 0x1818181818181818 [ 0.010000] MTRRfixed(269): 0x1818181818181818 ... [ 0.010000] MTRRfixed(26e): 0x1818181818181818 [ 0.010000] MTRRfixed(26f): 0x1818181818181818 (i.e. reads and writes to the specified ranges are going to DRAM) to (see first output for CPU 0): [ 0.000000] MTRRfixed(268): 0x1010101010101010 [ 0.000000] MTRRfixed(269): 0x1010101010101010 ... [ 0.000000] MTRRfixed(26e): 0x1515151515151515 [ 0.000000] MTRRfixed(26f): 0x1515151515151515 This in turn means that reads got to DRAM but writes go to IO. We just do not know what the BIOS has performed on CPU0 with those RdMem/WrMem settings, maybe it is changing that later on. But as we don't know it we shouldn't touch those bits. (*) "potentially" because my debug patch did not show RdMem/WrMem bits when fixed MTRR were set on CPU2 and CPU3. Furthermore the mainline kernel w/ and w/o my patch did change the memory type for following ranches on CPUs 2 and 3: [ 0.010000] MTRRfixed(26e): 0x1818181818181818 [ 0.010000] MTRRfixed(26f): 0x1818181818181818 which was type 0 (uncached) (when masking the RdMem/WrMem bits) to [ 0.130000] MTRRfixed(26e): 0x0505050505050505 [ 0.130000] MTRRfixed(26f): 0x0505050505050505 i.e. type 5 (write-protect). If there are no objections I'll submit "[PATCH] x86: mtrr: don't modify RdDram/WrDram bits of fixed MTRRs" for upstream integration. -- Configure bugmail: http://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is. ------------------------------------------------------------------------------ Open Source Business Conference (OSBC), March 24-25, 2009, San Francisco, CA -OSBC tackles the biggest issue in open source: Open Sourcing the Enterprise -Strategies to boost innovation and cut costs with open source participation -Receive a $600 discount off the registration fee with the source code: SFAD http://p.sf.net/sfu/XcvMzF8H _______________________________________________ acpi-bugzilla mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/acpi-bugzilla
