NEWS

RAS DAEMON
==========

In Kernel 3.5 we've started to address the long-discussed need of having a
better way to handle platform Reliability, Availability and Serviceability
(RAS).

Basically, a tracepoint event that handles memory errors called ras:mc_event
was added there, together with HERM/EDAC version 3.0 patches.

In Kernel 3.8, a new event was added, to handle PCIe AER events (ras:aer_event)
[1].

On kernel 3.9, a new driver was added to report hardware memory errors that
comes from the BIOS via ras:mc_event (the new ghes_edac driver).

It is still on my TODO list to add a RAS trace event for non-memory related
errors that come via the MCA machine check handler (mcelog).

While progress made was made at Kernel infrastructure, the needed userspace
tools were still lacking. So, I decided to start materializing the userspace
counterpart for what it was informally named as rasdaemon on some discussions.

The rasdaemon tool is available at:
	http://git.infradead.org/users/mchehab/rasdaemon.git

The current version is on very early stages, and it has a copy on it of
the library that Steven Rostedt's is writing for trace-cmd tool. The plan
is to use the trace-cmd library, when it starts to packaged as a separate
library. I'd like to thanks Steven for the help he gave me to write this
initial version.

The current version of the tool enables the ras:mc_event log, and reads
it via the raw trace debugfs node:
	/sys/kernel/debug/tracing/per_cpu/cpu*/trace_pipe_raw

It also has a code that allows recording the errors via an sqlite3 database.

The long term plan is to provide a tool that will catch and handle all
ras:* error events that comes from the Kernel tracing infrastructure,
logging them and providing tools to report it, being able to detect burst
errors (like the ones caused by a solar storm at memories) or sparsed errors,
in a way that would provide a glue to the users about the root cause of the
error.

Of course, there are much to do there.

It is a natural evolution of the tool to add support there for the
ras:aer_event traces that can come from PCIe AER.

While it currently works with current Kernels since kernel 3.5, there are a
number of interesting changes at tracing that are planned to be merged for
Kernel 3.10:
	- poll() support for per_cpu trace_pipe_raw;
	- a timestamp that could more easily associated with machine's
	  uptime;
	- support for a separate ringbuffer for RAS.

So, it is planned the minimal requirement for the final version (v1.0)
would be kernel 3.10.

This is currently on very early staging. Help is needed ;)

So, please send us suggestions, patches etc to the EDAC mailing list:
	linux-edac@vger.kernel.org

Thanks,
Mauro Carvalho Chehab
2013-03-14

-

[1] Currently, ras:mc_event is at include/ras/. It is on my todo list
to move it to be together with ras:aer_event, at include/trace/events/ras.h.