----- Original Message ----- > On Mon, Feb 10, 2014 at 2:11 PM, Dave Anderson <anderson@xxxxxxxxxx> wrote: > > > > Hi Andy, > > > > I've got a ELF kdump vmcore that was created in-house from a kernel configured > > with CONFIG_RANDOMIZE_BASE. I thought I might be able to analyze it by applying > > your earlier patch that introduced the --kaslr option. The kernel does not > > have the offset registered in the vmcoreinfo, and so I'm trying to determine > > the offset, but with no luck. > > > > Earlier, Kees had mentioned this: > > > >>> FWIW, the offset reported during a panic to dmesg is: > >>> (unsigned long)&_text - __START_KERNEL > > > > Where does it get reported during a panic exactly? Here's the oops trace, gotten > > by running "strings" on the vmcore: > > The commit that reports it is here: f32360ef6608434a032dc7ad262d45e9693c27f3 > > And maybe related, but 6723734cdff15211bb78aeea76ca847374bd93ae makes > sure panic handlers are called before kmsg_dump. > > And "strings" doesn't show anything starting with "Kernel Offset:" ? > Maybe it's not being saved in the kcore? Correct: $ strings vmcore | grep 'Kernel Offset' 0Kernel Offset: 0x%lx from 0x%lx (relocation range: 0x%lx-0x%lx) 0Kernel Offset: 0x%lx from 0x%lx (relocation range: 0x%lx-0x%lx) $ And that's because when kdump is enabled, crash_kexec() does not return: void panic(const char *fmt, ...) { ... [ cut ] ... /* * If we have crashed and we have a crash kernel loaded let it handle * everything else. * Do we want to call this before we try to display a message? */ crash_kexec(NULL); /* * Note smp_send_stop is the usual smp shutdown function, which * unfortunately means it may not be hardened to work in a panic * situation. */ smp_send_stop(); /* * Run any panic handlers, including those that might need to * add information to the kmsg dump output. */ atomic_notifier_call_chain(&panic_notifier_list, 0, buf); kmsg_dump(KMSG_DUMP_PANIC); ... So for kdump, the panic_notifier_list is useless. That's why the vmcoreinfo addition is necessary. Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility