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Re: [Xen-devel] Testing status of HVM (Intel VT) on 64bit XEN unstable c

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] Testing status of HVM (Intel VT) on 64bit XEN unstable c/s 11616
From: Ed Smith <esmith@xxxxxxxxxxxxxxx>
Date: Tue, 26 Sep 2006 14:31:12 -0400
Cc: Xen Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Steven Hand <Steven.Hand@xxxxxxxxxxxx>
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Keir Fraser wrote:
On 26/9/06 16:33, "Ed Smith" <esmith@xxxxxxxxxxxxxxx> wrote:

any chance you can test with debug=y ? The back-traces aren't
really very useful otherwise.
These are automated builds and tests that run each night.  We don't
normally build a debug XEN as we try and test the bits a customer
would run.  If these backtraces are useful in the release build how
will we diagnose crashes on a customer's site?

They take more deciphering, sometimes with the aid of the xen-syms file, as
the backtrace contains functions that aren't really in the call chain (and
misses some that are). It's less time consuming with a debug build, and
there's less reliance on the xen-syms file, as we include frame pointers.

Trying to match customer bits doesn't make sense. There is no customer for
these bits! So why throw away debug info during development testing just
because there are situations where debug info is not available? Is it
considered good training for developers? :-)

 -- Keir

Debug builds are fine and certainly easier to well, debug with, but they often
run slower than release builds and hide problems.  Humm... I wonder if thats
why you are not seeing this problem.  Also when we rely on debug builds to
diagnose problems we do not design in the ability to diagnose problems when
the bits are in customers hands.  'Good training for developers'?  No just
trying to work towards a released product that is easier to debug because
just enough debug-ability is built-in.

I'm building a debug build now and will post the results of booting a 64bit
HVM guest on it.  Hopefully that will help diagnose this problem.


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