Re: [RFC/SERIOUS] grilling troubled CPUs for fun and profit?

[Dave Jones <davej@redhat.com>]

On Mon, Jun 19, 2006 at 04:47:37PM -0400, linux-os (Dick Johnson) wrote:

 > > Why do you think we go to the bother of installing a double fault handler if
 > > we're going to reset? Why would we go to the bother of printk'ing
 > > information about the double fault if we're about to reset faster than
 > > it would get to a serial console ?
 > 
 > I don't know why you go to the bother of installing such a handler.

I even explained why in my mail.

 "The box intentionally locks up, so we have a chance to know wtf happened."

What's easier to debug: A box that just spontaneously reboots, or a box
that locks up with doublefault information on screen ?

 > Have you actually gotten it to print something? All my experience
 > with double-faults (and many with your RH Linux, BTW) result in
 > the screen going blank, the POST starting, and the machine re-booting.

No release of Red Hat Linux ever shipped with a double fault hander.
RHEL4 is the only product we sell that has it. Fedora also has it since
FC2 iirc.

 > > Your single datapoint is just that, a single datapoint.
 > > There are a number of reported cases of CPUs frying themselves.
 > > Here's one: http://www.tomshardware.com/2001/09/17/hot_spot/page4.html
 > > Google no doubt has more.
 > >
 > > Another anecdote: Upon fan failure, I once had an athlon MP *completely shatter*
 > > (as in broke in two pieces) under extreme heat.
 > >
 > > This _does_ happen.
 > 
 > Maybe it wasn't a FAN failure?

Same fan was transplanted to another box after that death, where it
was found to be as dead as the CPU & board it was previously plugged into.

Given the heat of the dead CPU, it's safe to say it wasn't operation
at time of death.

		Dave

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