[Linux-aus] CPU errors

[Russell Coker]

https://www.theregister.com/2021/06/04/google_chip_flaws/

I've been considering this issue of flaws in CPUs ever since it first was 
reported 4 years ago.

https://arxiv.org/pdf/2102.11245

There is no good data published about how common such problems are but 
Facebook states "hundreds" of CPUs out of "hundreds of thousands" of systems 
which implies something like 1/1000.

Over the years the number of machines I've run (with actual root access - not 
counting cloud VMs) adds up to more than 1000.  I expect that there are people 
on this list who have run 1000+ machines at one time.

If something has an incidence of 1/1000 there's a good chance that it has 
happened to a system that I run, and the probability that none of the systems 
run by people on this list have had the problem would be very low.

Has anyone seen such things and known it?  If not does that imply that some of 
us are just losing data for ourselves and our clients without knowing it?

The nearest I've come to seeing this is a Pentium D system that I got from 
corporate rubbish back when AMD64 systems were still new and rare.  I tried to 
install Debian on it and it got SEGVs on uncompressing packages.  I replaced 
the RAM with no change (desktop system without ECC support) and then just sent 
it to e-waste without any further thought.  In retrospect I should have done 
more research on that system to find out what was wrong, but at the time I was 
more focussed on getting working systems than on studying computer 
engineering.

Modern CPUs have caches that are bigger than the hard drives in early Linux 
systems.  The PC I'm using to write this message has 46M of CPU cache which is 
larger than the storage of the iPaQs I was running Linux on 20 years ago.  Has 
anyone written a recovery image that will lock itself into the cache, verify 
checksums, and then test things like RAM for errors?

-- 
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