[Crash-utility] [PATCH] xen: Add support for dom0 with Linux kernel 3.19 and newer

[Dave Anderson]

----- Original Message -----
> Hi Dave,
> 
> Sorry for delay but I have missed your email.
> 
> On Thu, Jan 21, 2016 at 04:34:15PM -0500, Dave Anderson wrote:
> >
> > ----- Original Message -----
> > >
> > > Linux kernel commit 054954eb051f35e74b75a566a96fe756015352c8
> > > (xen: switch to linear virtual mapped sparse p2m list), which
> > > appeared in 3.19, introduced linear virtual mapped sparse p2m
> > > list. If readmem() reads p2m then it access this list using
> > > physical addresses. Sadly, VMA to physical address translation
> > > in crash requires access to p2m list. This means that we have
> > > a chicken and egg problem. In general this issue must be solved
> > > by introducing some changes in libxl, Linux kernel and crash
> > > (I have added this task to my long TODO list). However, in dom0
> > > case we can use crash_xen_info_t.dom0_pfn_to_mfn_frame_list_list
> > > which is available out of the box. So, let's use it and make
> > > at least some users happy.
> > >
> > > Signed-off-by: Daniel Kiper <daniel.kiper at oracle.com>
> >
> > Hi Daniel,
> >
> > Can you help me out with a consise changelog entry?  As I understand
> > it, the crash utility has not supported Xen dom0 and domU dumpfiles
> > since the referenced 3.19 commit, and this patch resurrects support
> > for dom0 dumpfiles only.  Are there issues with live system analysis
> 
> Exactly!

OK.

> > as well?
> 
> I am not sure what do you mean by that. If you are asking about
> crash commands then it looks that after my fix everything works
> as expected.

No, I meant are there any problems when running crash on the live
system with those kernel versions?  (no vmcore)

Dave



> 
> > And without the patch, what is the final, fatal error message?
> 
> Here it is:
> 
> crash 7.1.4
> Copyright (C) 2002-2015  Red Hat, Inc.
> Copyright (C) 2004, 2005, 2006, 2010  IBM Corporation
> Copyright (C) 1999-2006  Hewlett-Packard Co
> Copyright (C) 2005, 2006, 2011, 2012  Fujitsu Limited
> Copyright (C) 2006, 2007  VA Linux Systems Japan K.K.
> Copyright (C) 2005, 2011  NEC Corporation
> Copyright (C) 1999, 2002, 2007  Silicon Graphics, Inc.
> Copyright (C) 1999, 2000, 2001, 2002  Mission Critical Linux, Inc.
> This program is free software, covered by the GNU General Public
> License,
> and you are welcome to change it and/or distribute copies of it under
> certain conditions.  Enter "help copying" to see the conditions.
> This program has absolutely no warranty.  Enter "help warranty" for
> details.
> 
> GNU gdb (GDB) 7.6
> Copyright (C) 2013 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show
> copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-unknown-linux-gnu"...
> 
> 
> crash: cannot resolve "p2m_top"
> 
> Daniel
>