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update fadump-howto

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1. yum is deprecated so use dnf instead
2. use the "kdumpctl reset-crashkernel --fadump=on" API

Reviewed-by: Philipp Rudo <prudo@redhat.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
This commit is contained in:
Coiby Xu 2022-03-01 17:30:30 +08:00
parent 1e7df3e1f3
commit 695e5b8676
1 changed files with 14 additions and 10 deletions
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24
fadump-howto.txt
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@ -39,7 +39,7 @@ kernel are one and the same on ppc64.
If you're reading this document, you should already have kexec-tools If you're reading this document, you should already have kexec-tools
installed. If not, you install it via the following command: installed. If not, you install it via the following command:
# yum install kexec-tools # dnf install kexec-tools
Fadump Operational Flow: Fadump Operational Flow:
@ -82,7 +82,7 @@ How to configure fadump:
Again, we assume if you're reading this document, you should already have Again, we assume if you're reading this document, you should already have
kexec-tools installed. If not, you install it via the following command: kexec-tools installed. If not, you install it via the following command:
# yum install kexec-tools # dnf install kexec-tools
Make the kernel to be configured with FADump as the default boot entry, if Make the kernel to be configured with FADump as the default boot entry, if
it isn't already: it isn't already:
@ -94,20 +94,24 @@ anything interesting in the way of debug analysis, you'll also need to install
the kernel-debuginfo package, of the same arch as your running kernel, and the the kernel-debuginfo package, of the same arch as your running kernel, and the
crash utility: crash utility:
# yum --enablerepo=\*debuginfo install kernel-debuginfo.$(uname -m) crash # dnf --enablerepo=\*debuginfo install kernel-debuginfo.$(uname -m) crash
Next up, we need to modify some boot parameters to enable firmware assisted Next up, we can enable firmware assisted dump and reserve the memory for boot
dump. With the help of grubby, it's very easy to append "fadump=on" to the end memory preservation as specified in in the table of 'FADump Memory Requirements'
of your kernel boot parameters. To reserve the appropriate amount of memory section:
for boot memory preservation, pass 'crashkernel=X' kernel cmdline parameter.
For the recommended value of X, see 'FADump Memory Requirements' section. # kdumpctl reset-crashkernel --fadump=on
Alternatively, you can use grubby to reserve custom amount of memory:
# grubby --args="fadump=on crashkernel=6G" --update-kernel=/boot/vmlinuz-`uname -r` # grubby --args="fadump=on crashkernel=6G" --update-kernel=/boot/vmlinuz-`uname -r`
By default, FADump reserved memory will be initialized as CMA area to make the By default, FADump reserved memory will be initialized as CMA area to make the
memory available through CMA allocator on the production kernel. We can opt out memory available through CMA allocator on the production kernel. We can opt out
of this, making reserved memory unavailable to production kernel, by booting the of this, making reserved memory unavailable to production kernel, by booting the
linux kernel with 'fadump=nocma' instead of 'fadump=on'. linux kernel with 'fadump=nocma' instead of 'fadump=on':
# kdumpctl reset-crashkernel --fadump=nocma
The term 'boot memory' means size of the low memory chunk that is required for The term 'boot memory' means size of the low memory chunk that is required for
a kernel to boot successfully when booted with restricted memory. By default, a kernel to boot successfully when booted with restricted memory. By default,
@ -350,6 +354,6 @@ Remove "crashkernel=" from kernel cmdline parameters:
If KDump is to be used as the dump capturing mechanism, reset the crashkernel parameter: If KDump is to be used as the dump capturing mechanism, reset the crashkernel parameter:
# kdumpctl reset-crashkernel `uname -r` # kdumpctl reset-crashkernel --fadump=off
Reboot the system for the settings to take effect. Reboot the system for the settings to take effect.