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RE: [Xen-devel] [PATCH][XEN]xm dump command add on

To: "Ken Hironaka" <hironaka.ken@xxxxxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [PATCH][XEN]xm dump command add on
From: "Graham, Simon" <Simon.Graham@xxxxxxxxxxx>
Date: Wed, 16 Aug 2006 13:01:42 -0400
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Thread-topic: [Xen-devel] [PATCH][XEN]xm dump command add on
Sorry to be slow replying - I have a couple of comments on the proposed

1. in xc_domain_dumpcore_via_callback why not just 'goto error_out;' if
sts<0? (as is done
   if the callback returns an error)

2. No big deal, but as I mentioned before, I don't know that there is
much value in having
   the -L and -C options to the 'xm dump-core' command since you can do
this by issuing 
   other xm commands before/after this one.

3. As others have commented, you really should log this command to
xend.log with log.info()
   (especially if you leave in the -L and -C options!) and the log
should include info on
   whether or not a pause/crash was done - this is very important when
you go back to try
   and work out why a domain paused or stopped unexpectedly!


> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Ken Hironaka
> Sent: Monday, August 14, 2006 4:04 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] [PATCH][XEN]xm dump command add on
> This adds the xm dump command to xend.
> The command outputs the memory contents of the specified domU to a
> coredump file.
> This will fail if tried on dom0.
> The interface is as follows:
> xm dump [-L][-C] <domID> [output path]
> -L Live dump:By default, xm dump does an xm pause, unpause before and
> after taking the dump, respectively. This option disables the
> pause/unpause and simply takes the dump.
> -C crash dump: This executes an xm destroy after the dump file is
> complete.
> The output path is optional, and if it is not specified, the path will
> be
> /var/xen/dump/<domU name>.<domU ID>.core
> This command uses the existant dumpCore(), which has been used for
> coredump when a domU crashed.
> In this patch, the xc_domain_dumpcore_via_callback() in xc_core.c of
> libxc is also modified. Previously, the
> xc_domain_dumpcore_via_callback() did not respond to error when
> copy_from_domain_page() failed. In other words, the dump core remained
> silent even if mapping the domain memory failed and its page could not
> be copied. When this happened, erroneous data had been dumped to the
> file without the user realizing it. Now, it has been modified so that
> if
> copy_from_domain_page fails, this fact is recorded in the logfile.
> However even in such cases, the dumping will continue as before.
> Signed-off-by: Ken Hironaka <hironaka.ken@xxxxxxxxxxxxxxxx>
> Reference
> http://lists.xensource.com/archives/html/xen-devel/2006-
> 08/msg00181.html
> http://lists.xensource.com/archives/html/xen-devel/2006-
> 08/msg00259.html
> http://lists.xensource.com/archives/html/xen-devel/2006-
> 08/msg00483.html

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