Re: Re: [RFC] RAS(Part II)--MCA enalbing in XEN

[Christoph Egger <Christoph.Egger@amd.com>]

On Tuesday 17 February 2009 07:41:29 Jiang, Yunhong wrote:
> I think the major difference including: a) How to handle the #MC, i.e.
> reset system, decide impacted components, take recover action like page
> offline etc. b) How to handle error impact guest. As to other item like
> log/telemetry, I think our implementation didn't have much different to
> current implementation.

The hardware doesn't know what recover actions the software can do.
If page A is faulty, and software maintains a copy in page B, then
software can turn an uncorrectable error into an correctable one.
If the hardware is aware of that copy (memory mirroring done by memory
controller), then the hardware itself turns the uncorrectable error
into an correctable one and reports an correctable error.

Therefore, I don't see why other flags than correctable and uncorrectable
are needed at all.


After some thinking on taking some quick actions, I can
agree on it if it meets the condition below. Be aware, error analyzes
is highly CPU vendor and even CPU family/model specific. Doing a
complete analyzes as Solaris does blows Xen up a *lot*.

Therefore, a *cheap* error analysis must be enough to figure out
if recover actions like page-offlining or cpu offlining
are *obviously* only the right thing to do.

If this is not the case, then let Dom0 decide what to do.

Christoph


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