Messages in this thread | | | Date | Wed, 29 Feb 2012 18:19:05 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 1/3] mce: Add a msg string to the MCE tracepoint |
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On Wed, Feb 29, 2012 at 05:11:08PM +0000, Luck, Tony wrote: > >> - on Nehalem, the MCE status register encodes not only the error message; it > >> also encodes the DIMM that generated the error. So, it is possible to > >> completely decode the error on userspace, using only the MCE registers. > > > > Well, depending on what Tony wants to do there, either decode the error > > in the kernel and pass it on with the 'msg' arg or do the whole decoding > > in userspace. > > For best results - we should decode right away in the kernel. Decoding later > requires that we carry a lot of additional information about the system > configuration at the time of the error. Consider the case of a hard error > (either fatal or recoverable). If the system reboots, then the DIMM > with the error should fail self test - and thus be mapped out of the system. > If the error analyzer doesn't realize that this has happened, it will be > very confused. Even if it does notice - the Sandy bridge decoder won't be > able to check that the right DIMM was mapped out (since the configuration > registers it reads to map addresses to DIMMS will now be set for the new > configuration, with different mappings).
Absolutely!
And also, you've lost the moment the system reboots and you haven't gotten all the info needed for decoding the error.
-- Regards/Gruss, Boris.
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