[PATCH] kexec-tools: Read always one vmcoreinfo file
daniel.kiper at oracle.com
Tue Jul 24 09:54:10 EDT 2012
On Tue, Jul 24, 2012 at 10:18:34AM +0200, Petr Tesarik wrote:
> Dne Po 23. ??ervence 2012 22:10:59 Daniel Kiper napsal(a):
> > Hi Petr,
> > On Mon, Jul 23, 2012 at 03:30:55PM +0200, Petr Tesarik wrote:
> > > Dne Po 23. ??ervence 2012 14:56:07 Petr Tesarik napsal(a):
> > > > Dne ??t 5. ??ervence 2012 14:16:35 Daniel Kiper napsal(a):
> > > > > vmcoreinfo file could exists under /sys/kernel (valid on baremetal
> > > > > only) and/or under /sys/hypervisor (valid when Xen dom0 is running).
> > > > > Read only one of them. It means that only one PT_NOTE will be always
> > > > > created. Remove extra code for second PT_NOTE creation.
> > > >
> > > > Hi Daniel,
> > > >
> > > > are you absolutely sure this is the right thing to do? IIUC these two
> > > > VMCORINFO notes are very different. The one from /sys/kernel/vmcoreinfo
> > > > describes the Dom0 kernel (type 'VMCOREINFO'), while the one from
> > > > /sys/hypervisor describes the Xen hypervisor (type 'XEN_VMCOREINFO').
> > > > If you keep only the hypervisor note, then e.g. makedumpfile won't be
> > > > able to use dumplevel greater than 1, nor will it be able to extract
> > > > the log buffer.
> > >
> > > I've just verified this, and I'm confident we have to keep both notes in
> > > the dump file. Simon, please revert Daniel's patch to avoid regressions.
> > >
> > > I'm attaching a sample VMCOREINFO_XEN and VMCOREINFO to demonstrate the
> > > difference. Note that the VMCOREINFO_XEN note is actually too big,
> > > because Xen doesn't bother to maintain the correct note size in the note
> > > header, so it always spans a complete page minus sizeof(Elf64_Nhdr)...
> > [...]
> > The problem with /sys/kernel/vmcoreinfo under Xen is that it expose invalid
> > physical address. It breaks /proc/vmcore in crash kernel. That is why I
> > proposed that fix. Additionally, /sys/kernel/vmcoreinfo is not available
> > under Xen Linux Ver. 2.6.18. However, I did not do any makedumpfile tests.
> > If you discovered any issues with my patch please drop me more details
> > about your tests (Xen version, Linux Kernel version, makedumpfile version,
> > command lines, config files, logs, etc.). I will be more then happy to
> > fix/improve kexec-tools and makedumpfile.
> Hi Daniel,
> well, Linux v2.6.18 does not have /sys/kernel/vmcoreinfo, simply because the
> VMCOREINFO infrastructure was not present in 2.6.18. It was added later with
> commit fd59d231f81cb02870b9cf15f456a897f3669b4e, which went into 2.6.24.
Hmmm... As I know 2.6.24 does not support kexec/kdump under Xen dom0. Correct?
> I tested with the following combinations:
> * xen-3.3.1 + kernel-xen-184.108.40.206 + kexec-tools-2.0.0 + makedumpfile-1.3.1
> * xen-4.0.3 + kernel-xen-220.127.116.11 + kexec-tools-2.0.0 + makedumpfile-1.3.1
> * xen-4.1.2 + kernel-xen-3.0.34 + kexec-tools-2.0.0 + makedumpfile-1.4.0
> These versions correspond to SLES11-GA, SLES11-SP1 and SLES11-SP2,
> respectively. All of them work just fine and save both ELF notes into the
Could you test current kexec-tools development version and
latest makedumpfile version on latest SLES version?
> What do you mean by "invalid physical address"? I'm getting the correct
> physical address under Xen. Obviously, it must be translated to machine
> addresses if you need them from the secondary kernel.
Correct vmcoreinfo address should be established by calling
Address exposed by /sys/kernel/vmcoreinfo is calculated in other way.
/sys/hypervisor/vmcoreinfo does it correctly (in older implementations
and in my new upstream implementation which I am going to post shortly).
> Anyway, let me re-install my test system and send all the necessary
> information. What kind of log files are you interested in?
If you spot any error in any logfile which in your opinion
is relevent to our testes please send me it.
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