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 debug and a helper to setup 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 non-zero value if kdump is not operational.
.TP
.I restart
Is equal to
.I start; stop
.TP
.I reload
reload 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 crash kernel in megabytes.
kdumpctl: Add kdumpctl estimate Resolves: bz1951415 Upstream: fedora Conflict: none commit e9e6a2c745d41f5447c0062525c0e4f3f489b903 Author: Kairui Song <kasong@redhat.com> Date: Thu Apr 22 03:27:10 2021 +0800 kdumpctl: Add kdumpctl estimate Add a rough esitimation support, currently, following memory usage are checked by this sub command: - System RAM - Kdump Initramfs size - Kdump Kernel image size - Kdump Kernel module size - Kdump userspace user and other runtime allocated memory (currently simply using a fixed value: 64M) - LUKS encryption memory usage The output of kdumpctl estimate looks like this: # kdumpctl estimate Reserved crashkernel: 256M Recommanded crashkernel: 160M Kernel image size: 47M Kernel modules size: 12M Initramfs size: 19M Runtime reservation: 64M Large modules: xfs: 1892352 nouveau: 2318336 And if the kdump target is encrypted: # kdumpctl estimate Encrypted kdump target requires extra memory, assuming using the keyslot with minimun memory requirement Reserved crashkernel: 256M Recommanded crashkernel: 655M Kernel image size: 47M Kernel modules size: 12M Initramfs size: 19M Runtime reservation: 64M LUKS required size: 512M Large modules: xfs: 1892352 nouveau: 2318336 WARNING: Current crashkernel size is lower than recommanded size 655M. The "Recommanded" value is calculated based on memory usages mentioned above, and will be adjusted accodingly to be no less than the value provided by kdump_get_arch_recommend_size. Signed-off-by: Kairui Song <kasong@redhat.com> Acked-by: Pingfan Liu <piliu@redhat.com> Signed-off-by: Kairui Song <kasong@redhat.com>
2021-04-21 19:27:10 +00:00
.TP
.I estimate
Estimate a suitable crashkernel value for current machine. This is a
best-effort estimate. It will print a recommanded crashkernel value
based on current kdump setup, and list some details of memory usage.
.TP
.I reset-crashkernel [KERNEL]
Reset crashkernel value to default value. kdumpctl will try to read
from /usr/lib/modules/<KERNEL>/crashkernel.default and reset specified
kernel's crashkernel cmdline value. If no kernel is
specified, will reset current running kernel's crashkernel value.
If /usr/lib/modules/<KERNEL>/crashkernel.default doesn't exist, will
simply exit return 1.
.SH "SEE ALSO"
.BR kdump.conf (5),
.BR mkdumprd (8)