** Changed in: crash (Ubuntu)
Status: In Progress => Fix Released
** Changed in: kexec-tools (Ubuntu)
Status: Fix Committed => Fix Released
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https://bugs.launchpad.net/bugs/1712867
Title:
[Hyper-V] 16.04 kexec-tools doesn't match linux-azure
Status in crash package in Ubuntu:
Fix Released
Status in kexec-tools package in Ubuntu:
Fix Released
Status in linux-azure package in Ubuntu:
Fix Committed
Status in crash source package in Xenial:
Fix Committed
Status in kexec-tools source package in Xenial:
Fix Committed
Status in linux-azure source package in Xenial:
Fix Committed
Bug description:
[Impact]
Currently it's not possible to use the kdump functionality in xenial
when running the linux-azure kernel. The problem is actually caused by
several factors:
1. kexec fails to parse /proc/kcore and thus fails to load the crash
kernel. That's similar to bug #1713940 and it's related to 4.10+
kernels.
2. When the crash kernel boots, a bug in KASLR causes it to crash in a
very early stage. For the user, it seems the system just rebooted
after the crash.
3. Currently in azure, crashkernel=128G is not enough to boot and run
the dump procedure with 4.11+ kernels. That value needs to be
increased in order to kdump to succeed.
4. After the vmcore is dumped, the current version of crash in xenial
is not able to parse it. All the necessary fixes are already upstream
and can be backported.
[Test Case]
1. Install the linux-azure kernel in an azure instance (although it's
possible to run linux-azure in bare metal or kvm, the KASLR issue only
is triggered in azure).
2. Follow the instructions in https://help.ubuntu.com/lts/serverguide
/kernel-crash-dump.html to setup kdump and manually trigger a crash
using /proc/sysrq-trigger.
The vmcore must be generated and it should be possible to inspect it
using crash.
3. Perform these same tests for the linux-generic kernel, on each
supported architecture.
[Regression Potential]
Since both kexec-tools and crash are being changed to support 4.10+
kernels, it's very important that they continue to handle 4.4 kernels
properly.
The same steps above can be used to test linux-generic for
regressions.
[Other Info]
Original description:
--8<--
Because the linux-azure kernel is based on 4.11, kexec on 16.04 gives the
following error:
kdump-tools[1436]: ELF core (kcore) parse failed
Perhaps the artful kexec-tools should be backported?
--8<--
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