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

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Message-ID: <5A4E9603.20778.21CD7C4@tim.ml.ipcopper.com>
Date:   Thu, 04 Jan 2018 13:00:51 -0800
From:   "Tim Mouraveiko" <tim.ml@...opper.com>
To:     Pavel Machek <pavel@....cz>
CC:     linux-kernel@...r.kernel.org
Subject: Re: Bricked x86 CPU with software?

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

> Hi!
> 
> > In all my years of extensive experience writing drivers and kernels, I never came across a situation 
> > where you could brick an x86 CPU. Not until recently, when I was working on debugging a piece of 
> > code and I bricked an Intel CPU. I am not talking about an experimental motherboard or anything 
> > exotic or an electrical issue where the CPU got fried, but before the software code execution the CPU 
> > was fine and then it´s dead. There were signs that something was not right, that the code was causing 
> > unusual behavior, which is what I was debugging.
> > 
> > Has anyone else ever experienced a bricked CPU after executing software code? I just wanted to get 
> > input from the community to see if anyone had had any experience like that, since it seems rather 
> > unusual to me.
> 
> Never seen that before. Can you try to brick another one? :-).
> 
> You may want to remove AC power and battery, wait for half an hour,
> then attempt to boot it...
> 
> 									Pavel
> -- 
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
>