Re: Bricked x86 CPU with software?

[Pavel Machek <pavel@ucw.cz>]

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Hi!

On Thu 2018-01-04 17:21:36, Tim Mouraveiko wrote:
> > On Thu 2018-01-04 14:13:56, Tim Mouraveiko wrote:
> > > > > 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.
> > > > >
> > > >
> > > > So you have code that killed more than one processor? Save it! We want
> > > > a copy.
> > > >
> > > > Do you have model numbers of affected CPUs?
> > >
> > >
> > > Why would you want a copy? Last time I checked bricked CPUs do not work well, even as
> > > decorations.
> > >
> > > I believe the processors were Intel Xeon series. The code would likely run on others too.
> >
> > Well... Intel's shares are overpriced, and you have code to fix that
> > :-).
> >
> > Actually... I don't think your code works. That's why I'm curious. But
> > if it works, its rather a big news... and I'm sure Intel and cloud
> > providers are going to be interested.
> >
> 
> I first discovered this issue over a year ago, quite by accident. I changed the code I was
> working on so as not to kill the CPU (as that is not what I was trying to). We made Intel aware
> of it. They didn´t care much, one of their personnel suggesting that they already knew about it
> (whether this is true or not I couldn´t say). It popped up again later, so I had to fix the code
> again. It could be a buggy implementation of a certain x86 functionality, but I left it at that
> because I had better things to do with my time.
>

Is the sequence available from ring 3, or does it need ring 0?

Can we get the code? Extraordinary claims and all that...

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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