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Re: [Xen-devel] [PATCH] xl: Check for dependencies in xl

To: Gianni Tedesco <gianni.tedesco@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] xl: Check for dependencies in xl
From: Kamala Narasimhan <kamala.narasimhan@xxxxxxxxx>
Date: Mon, 24 Jan 2011 12:26:36 -0500
Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
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> 
> NAK
> 
> Actually I think this type of check should go after the xenstore open
> has failed, just as an informational/hint type of thing IF it fails.
> Rather than applying what is really a heuristic and making it CAUSE a
> failure.
> 
Except xs_daemon_open called within libxl_ctx_init does not fail when xenstored 
is not running!  We get this non-obvious error message - "failed to free memory 
for the domain" at a later point.  This patch was an attempt to make the 
"xenstored not running" issue more obvious.  

So, without this check we might have to end up chasing xs_* calls that are 
bound to fail because of using the non null xs_handle returned by 
xs_daemon_open and apply this heuristic upon its failure to make the issue more 
obvious.  Given this info, do you still think we shouldn't perform this check?  
It would certainly make troubleshooting easier.

Alternately, we could investigate why xs_daemon_open is returning a non null 
handle when xenstored is not running.

Kamala



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