红帽全球峰会18.2. Enabling firmware assisted dump mechanism
You can enhance the crash dumping capabilities of IBM POWER systems by enabling the firmware assisted dump (fadump) mechanism.
In the Secure Boot environment, the GRUB boot loader allocates a boot memory region, known as the Real Mode Area (RMA). The RMA has a size of 512 MB, divided among the boot components. If a component exceeds its size allocation, GRUB fails with an out-of-memory (OOM) error.
Do not enable firmware assisted dump (fadump) mechanism in the Secure Boot environment on RHEL 9.1 and earlier versions. The GRUB boot loader fails with the following error:
error: ../../grub-core/kern/mm.c:376:out of memory.
Press any key to continue…
The system is recoverable only if you increase the default initramfs size due to the fadump configuration.
For information about workaround methods to recover the system, see the System boot ends in GRUB Out of Memory (OOM) article.
Prerequisites
- You have root permissions on the system.
Procedure
-
Install the
kexec-tools,kdump-utils, andmakedumpfilepackages. Configure the default value for
crashkernel:# kdumpctl reset-crashkernel --fadump=on --kernel=ALLOptional: Reserve boot memory instead of the default value:
# grubby --update-kernel ALL --args="fadump=on crashkernel=xxM"xxMis the required memory size in megabytes.注意When specifying boot configuration options, test the configurations by rebooting the kernel with
kdumpenabled. If thekdumpkernel fails to boot, increase thecrashkernelvalue gradually to set an appropriate value.Reboot for changes to take effect:
# reboot
'%20d='M201.5%20305.5c-13.8%200-24.9-11.1-24.9-24.6%200-13.8%2011.1-24.9%2024.9-24.9%2013.6%200%2024.6%2011.1%2024.6%2024.9%200%2013.6-11.1%2024.6-24.6%2024.6zM504%20256c0%20137-111%20248-248%20248S8%20393%208%20256%20119%208%20256%208s248%20111%20248%20248zm-132.3-41.2c-9.4%200-17.7%203.9-23.8%2010-22.4-15.5-52.6-25.5-86.1-26.6l17.4-78.3%2055.4%2012.5c0%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.3%2024.9-24.9s-11.1-24.9-24.9-24.9c-9.7%200-18%205.8-22.1%2013.8l-61.2-13.6c-3-.8-6.1%201.4-6.9%204.4l-19.1%2086.4c-33.2%201.4-63.1%2011.3-85.5%2026.8-6.1-6.4-14.7-10.2-24.1-10.2-34.9%200-46.3%2046.9-14.4%2062.8-1.1%205-1.7%2010.2-1.7%2015.5%200%2052.6%2059.2%2095.2%20132%2095.2%2073.1%200%20132.3-42.6%20132.3-95.2%200-5.3-.6-10.8-1.9-15.8%2031.3-16%2019.8-62.5-14.9-62.5zM302.8%20331c-18.2%2018.2-76.1%2017.9-93.6%200-2.2-2.2-6.1-2.2-8.3%200-2.5%202.5-2.5%206.4%200%208.6%2022.8%2022.8%2087.3%2022.8%20110.2%200%202.5-2.2%202.5-6.1%200-8.6-2.2-2.2-6.1-2.2-8.3%200zm7.7-75c-13.6%200-24.6%2011.1-24.6%2024.9%200%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.1%2024.9-24.6%200-13.8-11-24.9-24.9-24.9z'/%3e%3c/svg%3e){kind=small}