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update crashkernel-howto

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1. clean up left crashkernel.default
2. fix a few typos and grammar mistakes
3. ask the users to refer to `man kdumpctl` for reset-crashkernel

Philipp Rudo <prudo@redhat.com>

Signed-off-by: Coiby Xu <coxu@redhat.com>
This commit is contained in:
Coiby Xu 2022-04-18 15:54:53 +08:00
parent a1c63fa644
commit 683ff87821
1 changed files with 11 additions and 12 deletions
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23
crashkernel-howto.txt
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@ -37,10 +37,10 @@ Users can override the value during Anaconda installation manually.
Auto update of crashkernel boot parameter
=========================================
A new release of kexec-tools could update the default crashkernel value.
By default, kexec-tools would reset crashkernel to the new default value if it
detects old default crashkernel value is used by installed kernels. If you don't
want kexec-tools to update the old default crashkernel to the new default
A new release of kexec-tools could update the default crashkernel value. By
default, kexec-tools would reset crashkernel to the new default value if it
detects the old default crashkernel value is used by installed kernels. If you
don't want kexec-tools to update the old default crashkernel to the new default
crashkernel, you can change auto_reset_crashkernel to no in kdump.conf.
Supported Bootloaders
@ -67,19 +67,18 @@ value properly, `kdumpctl` also provides a sub-command:
`kdumpctl reset-crashkernel [--kernel=path_to_kernel] [--reboot]`
This command will read from the `crashkernel.default` file and reset
bootloader's kernel cmdline to the default value. It will also update bootloader
config if the bootloader has a standalone config file. User will have to reboot
the machine after this command to make it take effect if --reboot is not specified.
For ppc64le, an optional "[--fadump=[on|off|nocma]]" can also be specified to toggle
FADump on/off.
This command will reset the bootloader's kernel cmdline to the default value.
It will also update bootloader config if the bootloader has a standalone config
file. User will have to reboot the machine after this command to make it take
effect if --reboot is not specified. For more details, please refer to the
reset-crashkernel command in `man kdumpctl`.
Reset manually
--------------
To reset the crashkernel value manually, it's recommended to use utils like
`grubby`. A one liner script for resetting `crashkernel=` value of all installed
kernels to current boot kernel's crashkernel.default` is:
kernels to the default value is:
grubby --update-kernel ALL --args "crashkernel=$(kdumpctl get-default-crashkernel)"
@ -98,7 +97,7 @@ triggering kdump:
The output will be like this:
```
Encrypted kdump target requires extra memory, assuming using the keyslot with minimun memory requirement
Encrypted kdump target requires extra memory, assuming using the keyslot with minimum memory requirement
Reserved crashkernel: 256M
Recommended crashkernel: 655M