Messages in this thread | | | From | (Eric W. Biederman) | Date | Tue, 18 May 2010 15:14:08 -0700 | Subject | Re: Hardware Error Kernel Mini-Summit |
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Borislav Petkov <bp@amd64.org> writes:
> From: "Luck, Tony" <tony.luck@intel.com> > Date: Tue, May 18, 2010 at 03:08:58PM -0400 > >> > It makes sense to use the kernel's performance events >> > logging framework when we are logging events about how the >> > system performs. >> >> Perhaps it makes more sense to say that the Linux "performance >> events logging framework" has become more generic and is really >> now an "event logging framework". > > Yep, that's the idea. > >> > Furthermore it's NMI safe, offers structured logging, has >> > various streaming, multiplexing and filtering capabilities >> > that come handy for RAS purposes and more. >> >> Those of us present at the mini-summit were not familiar with >> all the features available. One area of concern was how to be >> sure that something is in fact listening to and logging the >> error events. My understanding is that if there is no process >> attached to an event, the kernel will just drop it. This is >> of particular concern because the kernel's first scan of the >> machine check banks occurs before there are any processes. >> So errors found early in boot (which might be saved fatal >> errors from before the boot) might be lost. > > Well, we have a trace_mce_record tracepoint in the mcheck code which > calls all the necessary callbacks when an mcheck occurs. For the time > being, the idea is to use the mce.c ring buffer for early mchecks and > copy them to the regular ftrace per-cpu buffer after the last has been > initialized. Later, we could switch to a another early bootmem buffer if > there's need to. > > Also, we want to have a userspace daemon that reads out the mces from > the trace buffer and does further processing like thresholding etc in > userspace. > > Concerning critical errors, there we bypass the perf subsystem and > execute the smallest amount of code possible while trying to shutdown > gracefully if the error type allows that. > > These are the rough ideas at least...
Can someone please tell me why everyone is eager to squirrel correctable error reports away and not report them in dmesg? aka syslog.
I have had on several occasions a machine with memory errors that mcelog or the BIOS was eating the error reports and not putting them anywhere a normal human being would look.
If your system isn't broken correctable errors are rare. People look at syslog. People look in /var/log/messages and dmesg when something goes weird.
I have no problem with additional interfaces to provide additional functionality but please can we put errors where people can find them.
Eric
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