Re: [PATCH v2 2/2] kexec-kdump-howto.txt: Add notes about device dump

Currently there are two issues with device dump: - It may use too much memory - kdump won't automatically include required driver in second kernel User should manually reserve enough memory, and include the required driver by using extra_modules. Add some notes about the issues in kexec-kdump-howto.txt Signed-off-by: Kairui Song <kasong(a)redhat.com&gt; --- kexec-kdump-howto.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/kexec-kdump-howto.txt b/kexec-kdump-howto.txt index 7e9e58a..109b13d 100644 --- a/kexec-kdump-howto.txt +++ b/kexec-kdump-howto.txt @@ -698,6 +698,22 @@ crash kernel according, or update your encryption setup. It's recommanded to use a non-encrypted target (eg. remote target) instead. +Notes on device dump: + +Device dump allows drivers to append dump data to vmcore, so you can +collect driver specified debug info. The drivers could append the +data without any limit, and the data is stored in memory, this may +bring a significant memory stress. So device dump is disabled by default +by passing "novmcoredd" command line option to the kdump capture kernel. +If you want to collect debug data with device dump, you need to modify +"KDUMP_COMMANDLINE_APPEND=" value in /etc/sysconfig/kdump and remove the +"novmcoredd" option. You also need to increase the reserved enough memory +in case of OOM issue. +Besides, kdump initramfs won't include the kernel modules which supports +device dump automatically. So to ensure the device dump data you are

+interested is included in the vmcore, you have to force include the module +by giving the module name in extra_modules list in /etc/kdump.conf + Parallel Dumping Operation ========================== Kexec allows kdump using multiple cpus. So parallel feature can accelerate -- 2.21.0 _______________________________________________ kexec mailing list -- kexec(a)lists.fedoraproject.org To unsubscribe send an email to kexec-leave(a)lists.fedoraproject.org Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/kexec@lists.fedoraproject.org