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Re: [Xen-devel] [Doc] writeup for error handling usage in XEN

To: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, "Ke, Liping" <liping.ke@xxxxxxxxx>
Subject: Re: [Xen-devel] [Doc] writeup for error handling usage in XEN
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Thu, 04 Dec 2008 15:35:44 +0000
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On 04/12/2008 15:17, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> It would be nice if ASSERT could be enabled at runtime rather
> than just at compile time.  If there were a global flag
> "enable_asserts" that could be enabled by a Xen grub command
> line option, and the ASSERT macro always tested that global
> flag before testing the assert-condition, then additional
> debug/checking code could be easily enabled with a very
> small runtime cost.  (The global variable would be checked
> frequently enough that it would always be in cache, and
> since it only changes once -- at bootime -- there would be
> no cache-synchronization costs.)

A patch to make runtime-selectable assertions a feature selectable at
compile time might be acceptable. I'd suggest just shipping debug and
non-debug hypervisors though, if you want extra boot-time selectable
debugging in the field. Or just have a private patch to always-enable
assertions, if you consider the cost low enough.

 -- Keir



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