linux-kernel - Re: [Xen-devel] [PATCH v2] xen, kdump: handle pv domain in paddr_vmcoreinfo

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Date:   Tue, 11 Apr 2017 12:49:39 +0200
From:   Petr Tesarik <ptesarik@...e.com>
To:     Daniel Kiper <daniel.kiper@...cle.com>
Cc:     jgross@...e.com, konrad.wilk@...cle.com,
        boris.ostrovsky@...cle.com, xen-devel@...ts.xenproject.org,
        eric.devolder@...cle.com, dkiper@...-space.pl,
        andrew.cooper3@...rix.com, linux-kernel@...r.kernel.org
Subject: Re: [Xen-devel] [PATCH v2] xen, kdump: handle pv domain in
 paddr_vmcoreinfo_note()

On Mon, 10 Apr 2017 22:49:33 +0200
Daniel Kiper <daniel.kiper@...cle.com> wrote:

> On Fri, Apr 07, 2017 at 11:16:22AM +0200, Petr Tesarik wrote:
> > On Wed, 5 Apr 2017 13:13:00 +0200
> > Petr Tesarik <ptesarik@...e.com> wrote:
> >
> > > On Tue, 4 Apr 2017 12:42:53 -0700 (PDT)
> > > Daniel Kiper <daniel.kiper@...cle.com> wrote:
> > >
> > >[...]
> > > > So, if Petr did relevant tests that is nice. However, then, IMO, this
> > > > patch begs Petr Tested-by.
> > >
> > > Actually, I tested with this patch applied on top of kernel 4.4 (SLES
> > > 12 SP2). It matches what traditional Xen had always done, so I am quite
> > > confident it will work with a later kernel, but to give my Tested-by,
> > > let me first re-run the test on master, hopefully until today EOB.
> >
> > It took me much longer than anticipated (I had some trouble setting up
> > the host again), but I can confirm that the patch works as expected on
> 
> No problem. I know how it works.
> 
> > top of 4.11-rc5.
> 
> Great!
> 
> > Without the patch, makedumpfile in the crash kernel complains:
> >
> > /proc/vmcore doesn't contain vmcoreinfo.
> 
> Though, I would like to ask you to do crash tool tests too.
> Could you do that?

I'm not sure what kind of tests you want me to perform. I'm not able to
save a dump file without the patch.

Well ... I could reserve enough memory to launch a crash session
directly in the kdump environment. I'll get to you later.

> > With the patch applied, dumping still fails later because of an
> > unrelated bug in makedumpfile, but I was able to extract the kernel
> > message buffer with "makedumpfile --dump-dmesg". This already confirms
> > VMCOREINFO presence and usability.
> 
> Is it Xen specific issue or more generic one?

It is Xen-specific, and I even have a patch now, about to be sent to
the kexec ML.

Petr T