hey Simon,
comments are enclosed
On Wed, 2006-08-16 at 13:01 -0400, Graham, Simon wrote:
> Sorry to be slow replying - I have a couple of comments on the proposed
> patch:
>
> 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)
>
just because dumping failed on one page, it doesn't mean that the whole
dump is useless. in fact, there are many cases where the debugger would
like to see even a little information to help him/her. so i think it is
better to keep on dumping even if an error has occured. especially with
live dump, the page table state can change even while dumping, and if
that is the case, the dump can fail to dump a page even if it is not
caused by a critical error. instead, a message that shows how many pages
failed as been logged.
> 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.
>
you are right, they can be combined with other commands, but i think
they are options that would be expected an a regular dump command.
> 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!
i am not sure if i am misundertanding your comment, but they are logged
into Xend.log. since they are combined with xm pause/unpause and
destory, they are also logged as well by default.
>
> Simon
best regards,
Ken
>
>
> > -----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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