kexec-tools/kdumpctl.8

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.TH KDUMPCTL 8 2015-07-13 kexec-tools
.SH NAME
kdumpctl \- control interface for kdump
.SH SYNOPSIS
.B kdumpctl
.I COMMAND
.SH DESCRIPTION
.B kdumpctl
is used to check or control the kdump service.
In most cases, you should use
.B systemctl
to start / stop / enable kdump service instead. However,
.B kdumpctl
provides more details for debugging and a helper to set up ssh key authentication.
.SH COMMANDS
.TP
.I start
Start the service.
.TP
.I stop
Stop the service.
.TP
.I status
Prints the current status of kdump service.
It returns a non-zero value if kdump is not operational.
.TP
.I restart
Is equal to
.I start; stop
.TP
.I reload
reload the crash kernel image and initramfs without triggering a rebuild.
.TP
.I rebuild
rebuild the crash kernel initramfs.
.TP
.I propagate
Helps to setup key authentication for ssh storage since it's
impossible to use password authentication during kdump.
.TP
.I showmem
Prints the size of reserved memory for the crash kernel in megabytes.
.TP
.I estimate
Estimate a suitable crashkernel value for the current machine. This is a
best-effort estimate. It will print a recommended crashkernel value
based on the current kdump setup, and list some details of memory usage.
.TP
.I get-default-crashkernel
Return the default crashkernel value provided by kexec-tools.
.TP
rewrite reset_crashkernel to support fadump and to used by RPM scriptlet Rewrite kdumpctl reset-crashkernel KERNEL_PATH as kdumpctl reset-crashkernel [--fadump=[on|off|nocma]] [--kernel=path_to_kernel] [--reboot] This interface would reset a specific kernel to the default crashkernel value given the kernel path. And it also supports grubby's syntax so there are the following special cases, - if --kernel not specified, - use KDUMP_KERNELVER if it's defined in /etc/sysconfig/kdump - otherwise use current running kernel, i.e. `uname -r` - if --kernel=DEFAULT, the default boot kernel is chosen - if --kernel=ALL, all kernels would have its crashkernel reset to the default value and the /etc/default/grub is updated as well --fadump=[on|off|nocma] toggles fadump on/off for the kernel provided in KERNEL_PATH. If --fadump is omitted, the dump mode is determined by parsing the kernel command line for the kernel(s) to update. CoreOS/Atomic/Silverblue needs to be treated as a special case because, - "rpm-ostree kargs" is used to manage kernel command line parameters so --kernel doesn't make sense and there is no need to find current running kernel - "rpm-ostree kargs" itself would prompt the user to reboot the system after modify the kernel command line parameter - POWER is not supported so we can assume the dump mode is always kdump This interface will also be called by kexec-tools RPM scriptlets [1] to reset crashkernel. Note the support of crashkenrel.default is dropped. [1] https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/ Reviewed-by: Pingfan Liu <piliu@redhat.com> Reviewed-by: Philipp Rudo <prudo@redhat.com> Signed-off-by: Coiby Xu <coxu@redhat.com>
2021-12-01 05:39:40 +00:00
.I reset-crashkernel [--kernel=path_to_kernel] [--reboot]
Reset crashkernel to default value recommended by kexec-tools. If no kernel
is specified, will reset KDUMP_KERNELVER if it's defined in /etc/sysconfig/kdump
or the current running kernel's crashkernel value if KDUMP_KERNELVER is empty. You can
rewrite reset_crashkernel to support fadump and to used by RPM scriptlet Rewrite kdumpctl reset-crashkernel KERNEL_PATH as kdumpctl reset-crashkernel [--fadump=[on|off|nocma]] [--kernel=path_to_kernel] [--reboot] This interface would reset a specific kernel to the default crashkernel value given the kernel path. And it also supports grubby's syntax so there are the following special cases, - if --kernel not specified, - use KDUMP_KERNELVER if it's defined in /etc/sysconfig/kdump - otherwise use current running kernel, i.e. `uname -r` - if --kernel=DEFAULT, the default boot kernel is chosen - if --kernel=ALL, all kernels would have its crashkernel reset to the default value and the /etc/default/grub is updated as well --fadump=[on|off|nocma] toggles fadump on/off for the kernel provided in KERNEL_PATH. If --fadump is omitted, the dump mode is determined by parsing the kernel command line for the kernel(s) to update. CoreOS/Atomic/Silverblue needs to be treated as a special case because, - "rpm-ostree kargs" is used to manage kernel command line parameters so --kernel doesn't make sense and there is no need to find current running kernel - "rpm-ostree kargs" itself would prompt the user to reboot the system after modify the kernel command line parameter - POWER is not supported so we can assume the dump mode is always kdump This interface will also be called by kexec-tools RPM scriptlets [1] to reset crashkernel. Note the support of crashkenrel.default is dropped. [1] https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/ Reviewed-by: Pingfan Liu <piliu@redhat.com> Reviewed-by: Philipp Rudo <prudo@redhat.com> Signed-off-by: Coiby Xu <coxu@redhat.com>
2021-12-01 05:39:40 +00:00
also specify --kernel=ALL and --kernel=DEFAULT which have the same meaning as
grubby's kernel-path=ALL and kernel-path=DEFAULT. ppc64le supports FADump and
supports an additional [--fadump=[on|off|nocma]] parameter to toggle FADump
rewrite reset_crashkernel to support fadump and to used by RPM scriptlet Rewrite kdumpctl reset-crashkernel KERNEL_PATH as kdumpctl reset-crashkernel [--fadump=[on|off|nocma]] [--kernel=path_to_kernel] [--reboot] This interface would reset a specific kernel to the default crashkernel value given the kernel path. And it also supports grubby's syntax so there are the following special cases, - if --kernel not specified, - use KDUMP_KERNELVER if it's defined in /etc/sysconfig/kdump - otherwise use current running kernel, i.e. `uname -r` - if --kernel=DEFAULT, the default boot kernel is chosen - if --kernel=ALL, all kernels would have its crashkernel reset to the default value and the /etc/default/grub is updated as well --fadump=[on|off|nocma] toggles fadump on/off for the kernel provided in KERNEL_PATH. If --fadump is omitted, the dump mode is determined by parsing the kernel command line for the kernel(s) to update. CoreOS/Atomic/Silverblue needs to be treated as a special case because, - "rpm-ostree kargs" is used to manage kernel command line parameters so --kernel doesn't make sense and there is no need to find current running kernel - "rpm-ostree kargs" itself would prompt the user to reboot the system after modify the kernel command line parameter - POWER is not supported so we can assume the dump mode is always kdump This interface will also be called by kexec-tools RPM scriptlets [1] to reset crashkernel. Note the support of crashkenrel.default is dropped. [1] https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/ Reviewed-by: Pingfan Liu <piliu@redhat.com> Reviewed-by: Philipp Rudo <prudo@redhat.com> Signed-off-by: Coiby Xu <coxu@redhat.com>
2021-12-01 05:39:40 +00:00
on/off.
rewrite reset_crashkernel to support fadump and to used by RPM scriptlet Rewrite kdumpctl reset-crashkernel KERNEL_PATH as kdumpctl reset-crashkernel [--fadump=[on|off|nocma]] [--kernel=path_to_kernel] [--reboot] This interface would reset a specific kernel to the default crashkernel value given the kernel path. And it also supports grubby's syntax so there are the following special cases, - if --kernel not specified, - use KDUMP_KERNELVER if it's defined in /etc/sysconfig/kdump - otherwise use current running kernel, i.e. `uname -r` - if --kernel=DEFAULT, the default boot kernel is chosen - if --kernel=ALL, all kernels would have its crashkernel reset to the default value and the /etc/default/grub is updated as well --fadump=[on|off|nocma] toggles fadump on/off for the kernel provided in KERNEL_PATH. If --fadump is omitted, the dump mode is determined by parsing the kernel command line for the kernel(s) to update. CoreOS/Atomic/Silverblue needs to be treated as a special case because, - "rpm-ostree kargs" is used to manage kernel command line parameters so --kernel doesn't make sense and there is no need to find current running kernel - "rpm-ostree kargs" itself would prompt the user to reboot the system after modify the kernel command line parameter - POWER is not supported so we can assume the dump mode is always kdump This interface will also be called by kexec-tools RPM scriptlets [1] to reset crashkernel. Note the support of crashkenrel.default is dropped. [1] https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/ Reviewed-by: Pingfan Liu <piliu@redhat.com> Reviewed-by: Philipp Rudo <prudo@redhat.com> Signed-off-by: Coiby Xu <coxu@redhat.com>
2021-12-01 05:39:40 +00:00
Note: The memory requirements for kdump varies heavily depending on the
used hardware and system configuration. Thus the recommended
crashkernel might not work for your specific setup. Please test if
kdump works after resetting the crashkernel value.
.SH "SEE ALSO"
.BR kdump.conf (5),
.BR mkdumprd (8)