Hi Kairui, On 05/29/19 at 06:28pm, Kairui Song wrote:
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@redhat.com
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
Better to add more words eg. below:
kdump initramfs only includes device drivers which are required by the dump target setups, you can force include the device drivers for device dump by using extra_modules option in /etc/kdump.conf
+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
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Thanks Dave