I finally had some time to play around with this locally (not on AWS, so things still might differ as there could be a dependency on the version of the Xen hyperviror as well). The default setup I used initially failed for memory issues. But then I used full server installations in a HVM guest (which brings many more modules). So tweaking the modules to include by setting
/etc/initramfs-tools/initramfs.conf: MODULES=dep and /etc/default/grub.d/kexec-tools.cfg: crashkernel=256M may or my not be required for EC2. The main problem seemed to be related to unplugging the emulated devices (in favour of the pv drivers). The only variant that seemed to partially work for me was to use "xen_emul_unplug=never" for the normal boot. Of course this is not really ideal as this impacts normal usage performance. This also only worked as much as creating a dump but it took a bit of time since the network interface would not come up. A RH bug suggests a slight variation which supposedly avoids using the emulated drivers. But either I mis-read the instructions or it just does not work in our environment. At least those attempts just hung like before. [1] https://bugzilla.redhat.com/show_bug.cgi?id=815785 ** Bug watch added: Red Hat Bugzilla #815785 https://bugzilla.redhat.com/show_bug.cgi?id=815785 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1421391 Title: can't kdump in trusty ec2 instance Status in linux package in Ubuntu: Incomplete Bug description: [Impact] I can't get a crash dump in an ec2 trusty instance. When it kexecs, I see the following backtrace: [ 0.813826] ------------[ cut here ]------------ [ 0.817517] WARNING: CPU: 0 PID: 1 at /build/buildd/linux-3.13.0/arch/x86/mm/ioremap.c:102 __ioremap_caller+0x374/0x380() [ 0.823494] Modules linked in: [ 0.825807] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.13.0-44-generic #73-Ubuntu [ 0.829917] Hardware name: Xen HVM domU, BIOS 4.2.amazon 12/03/2014 [ 0.833266] 0000000000000009 ffff8800362f1c18 ffffffff81720d86 0000000000000000 [ 0.838861] ffff8800362f1c50 ffffffff810677cd ffffea0000ff0640 000000000003fc19 [ 0.844463] 000000003fc19000 000000000003fc19 0000000000001000 ffff8800362f1c60 [ 0.850005] Call Trace: [ 0.851708] [<ffffffff81720d86>] dump_stack+0x45/0x56 [ 0.854563] [<ffffffff810677cd>] warn_slowpath_common+0x7d/0xa0 [ 0.857735] [<ffffffff810678aa>] warn_slowpath_null+0x1a/0x20 [ 0.860855] [<ffffffff81056ba4>] __ioremap_caller+0x374/0x380 [ 0.864047] [<ffffffff8104b528>] ? copy_oldmem_page+0x48/0xc0 [ 0.867193] [<ffffffff81056be4>] ioremap_cache+0x14/0x20 [ 0.870123] [<ffffffff8104b528>] copy_oldmem_page+0x48/0xc0 [ 0.873223] [<ffffffff81231fd4>] read_from_oldmem.part.0+0xa4/0xe0 [ 0.876534] [<ffffffff8123222b>] elfcorehdr_read_notes+0x1b/0x20 [ 0.879797] [<ffffffff81d66809>] merge_note_headers_elf64.constprop.7+0x71/0x24a [ 0.883949] [<ffffffff81d67188>] ? vmcore_init.part.4+0x55d/0x55d [ 0.887380] [<ffffffff81d66dbd>] vmcore_init.part.4+0x192/0x55d [ 0.890670] [<ffffffff81d67188>] ? vmcore_init.part.4+0x55d/0x55d [ 0.894075] [<ffffffff81d671b9>] vmcore_init+0x31/0x33 [ 0.897022] [<ffffffff8100214a>] do_one_initcall+0xfa/0x1b0 [ 0.900121] [<ffffffff81089555>] ? parse_args+0x225/0x3f0 [ 0.903231] [<ffffffff81d360f6>] kernel_init_freeable+0x17b/0x200 [ 0.906683] [<ffffffff81d358e5>] ? do_early_param+0x88/0x88 [ 0.909814] [<ffffffff8170f250>] ? rest_init+0x80/0x80 [ 0.912777] [<ffffffff8170f25e>] kernel_init+0xe/0x130 [ 0.915648] [<ffffffff817317bc>] ret_from_fork+0x7c/0xb0 [ 0.918684] [<ffffffff8170f250>] ? rest_init+0x80/0x80 [ 0.921565] ---[ end trace 8b6e218b41648bbd ]--- [ Test Case ] boot ec2 trusty instance sudo apt-get install linux-crashdump sudo sed -i 's/USE_KDUMP=0/USE_KDUMP=1/' /etc/default/kdump-tools sudo reboot sudo kdump-config show echo c | sudo tee /proc/sysrq-trigger To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1421391/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
