** Description changed: + [Impact] + + Currently it's not possible to use the kdump functionality in xenial + when running the linux-azure kernel. The problem is actually caused but + 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. + + [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<--
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1712867 Title: [Hyper-V] 16.04 kexec-tools doesn't match linux-azure To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/crash/+bug/1712867/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
