linux-kernel - Re: Bricked x86 CPU with software?

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Date:   Thu, 4 Jan 2018 20:51:27 -0500
From:   james harvey <jamespharvey20@...il.com>
To:     Tim Mouraveiko <tim.ml@...opper.com>
Cc:     Pavel Machek <pavel@....cz>,
        kernel list <linux-kernel@...r.kernel.org>
Subject: Re: Bricked x86 CPU with software?

On Thu, Jan 4, 2018 at 4:00 PM, Tim Mouraveiko <tim.ml@...opper.com> wrote:
> Pavel,
>
> As I mentioned before, I repeatedly and fully power-cycled the motherboard and reset BIOS
> and etc. It made no difference. I can see that the processor was not drawing any power. The
> software code behaved in a similar fashion on other processors, until I fixed it so that it would
> not kill any more processors.
>
> In case you are curious there was no overheating, no 100% utilization, no tampering with
> hardware (GPIO pins or anything of that sort), no overclocking and etc. No hardware issues
> or changes at all.
>
> Tim

To clarify, by "in a similar fashion on other processors", do you
actually mean you consistently bricked multiple CPUs using the same
code?  Or, was it just this one CPU that bricked, and it was just
acting buggy on other processors?

Unless you consistently bricked multiples, my bet is coincidence.  In
your original post, "There were signs that something was not right,
that the code was causing unusual behavior, which is what I was
debugging." makes me think it was a defective CPU but still
functional, and died as you were debugging/running the buggy code.