Factor out kdump_get_arch_recommend_crashkernel to prepare for kdump-anaconda-plugin for example to retrieve the default crashkernel value.

Note the support of crashkenrel.default is dropped.

Signed-off-by: Coiby Xu coxu@redhat.com --- kdump-lib.sh | 60 +++++++++++++++++++++++++++++++--------------------- 1 file changed, 36 insertions(+), 24 deletions(-)

diff --git a/kdump-lib.sh b/kdump-lib.sh index b8f6c96..b28db44 100755 --- a/kdump-lib.sh +++ b/kdump-lib.sh @@ -822,40 +822,52 @@ get_recommend_size() IFS="$OLDIFS" }

+# get default crashkernel +# $1 dump mode, if not specified, dump_mode will be judged by is_fadump_capable +kdump_get_arch_recommend_crashkernel() +{ + local _arch _ck_cmdline _dump_mode + + if [[ -z "$1" ]]; then + if is_fadump_capable; then + _dump_mode=fadump + else + _dump_mode=kdump + fi + else + _dump_mode=$1 + fi + + _arch=$(uname -m) + + if [[ $_arch == "x86_64" ]] || [[ $_arch == "s390x" ]]; then + _ck_cmdline="1G-4G:192M,4G-64G:256M,64G-:512M" + elif [[ $_arch == "aarch64" ]]; then + _ck_cmdline="2G-:448M" + elif [[ $_arch == "ppc64le" ]]; then + if [[ $_dump_mode == "fadump" ]]; then + _ck_cmdline="4G-16G:768M,16G-64G:1G,64G-128G:2G,128G-1T:4G,1T-2T:6G,2T-4T:12G,4T-8T:20G,8T-16T:36G,16T-32T:64G,32T-64T:128G,64T-:180G" + else + _ck_cmdline="2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G" + fi + fi + + _ck_cmdline=${_ck_cmdline//-:/-102400T:} + echo -n "$_ck_cmdline" +} + # return recommended size based on current system RAM size # $1: kernel version, if not set, will defaults to $(uname -r) kdump_get_arch_recommend_size() { - local kernel=$1 arch + local _ck_cmdline

if ! [[ -r "/proc/iomem" ]]; then echo "Error, can not access /proc/iomem." return 1 fi - - [[ -z $kernel ]] && kernel=$(uname -r) - ck_cmdline=$(cat "/usr/lib/modules/$kernel/crashkernel.default" 2> /dev/null) - - if [[ -n $ck_cmdline ]]; then - ck_cmdline=${ck_cmdline#crashkernel=} - else - arch=$(lscpu | grep Architecture | awk -F ":" '{ print $2 }' | tr '[:lower:]' '[:upper:]') - if [[ $arch == "X86_64" ]] || [[ $arch == "S390X" ]]; then - ck_cmdline="1G-4G:192M,4G-64G:256M,64G-:512M" - elif [[ $arch == "AARCH64" ]]; then - ck_cmdline="2G-:448M" - elif [[ $arch == "PPC64LE" ]]; then - if is_fadump_capable; then - ck_cmdline="4G-16G:768M,16G-64G:1G,64G-128G:2G,128G-1T:4G,1T-2T:6G,2T-4T:12G,4T-8T:20G,8T-16T:36G,16T-32T:64G,32T-64T:128G,64T-:180G" - else - ck_cmdline="2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G" - fi - fi - fi - - ck_cmdline=${ck_cmdline//-:/-102400T:} sys_mem=$(get_system_size) - + _ck_cmdline=$(kdump_get_arch_recommend_crashkernel) get_recommend_size "$sys_mem" "$ck_cmdline" }

Add a helper function to get dump mode. The dump mode would be - fadump if fadump=on or fadump=nocma - kdump if fadump=off or empty fadump

Otherwise return 1.

Also add another helper function to return a kernel's dump mode.

Signed-off-by: Coiby Xu coxu@redhat.com --- kdumpctl | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+)

diff --git a/kdumpctl b/kdumpctl index 7fc3a4d..c6046dc 100755 --- a/kdumpctl +++ b/kdumpctl @@ -1317,6 +1317,40 @@ get_grub_kernel_boot_parameter() grubby --info="$_kernel_path" | sed -En -e "/^args=.*$/{s/^.*(\s|")${_para}=(\S*).*"$/\2/p;q}" }

+# get dump mode by fadump value +# return +# - fadump, if fadump=on or fadump=nocma +# - kdump, if fadump=off or empty fadump, return kdump +# - error if otherwise +get_dump_mode_by_fadump_val() +{ + local _fadump_val=$1 + + if [[ -z $_fadump_val ]] || [[ $_fadump_val == off ]]; then + echo -n kdump + elif [[ $_fadump_val == on ]] || [[ $_fadump_val == nocma ]]; then + echo -n fadump + else + derror "invalid fadump=$_fadump_val" + return 1 + fi +} + +# get dump mode of a specific kernel +# based on its fadump kernel cmdline parameter +get_dump_mode_by_kernel() +{ + local _kernel_path=$1 _fadump_val _dump_mode + + _fadump_val=$(get_grub_kernel_boot_parameter "$_kernel_path" fadump) + if _dump_mode=$(get_dump_mode_by_fadump_val "$_fadump_val"); then + echo -n "$_dump_mode" + else + derror "failed to get dump mode for kernel $_kernel_path" + exit + fi +} + reset_crashkernel() { local kernel=$1 entry crashkernel_default

CoreOS/Atomic/Silverblue use "rpm-ostree kargs" to manage kernel command line parameters.

Fixes: commit 86130ec10fda37cc283f717eaacb56a4cbf76418 ("kdumpctl: Add kdumpctl reset-crashkernel") Signed-off-by: Coiby Xu coxu@redhat.com --- kdumpctl | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kdumpctl b/kdumpctl index c01f8ae..27971a1 100755 --- a/kdumpctl +++ b/kdumpctl @@ -1396,9 +1396,9 @@ reset_crashkernel()

if is_atomic; then if rpm-ostree kargs | grep -q "crashkernel="; then - rpm-ostree --replace="crashkernel=$crashkernel_default" + rpm-ostree kargs --replace="crashkernel=$crashkernel_default" else - rpm-ostree --append="crashkernel=$crashkernel_default" + rpm-ostree kargs --append="crashkernel=$crashkernel_default" fi else entry=$(grubby --info ALL | grep "^kernel=.*$kernel")

kexec-tools could update the default crashkernel value. When auto_reset_crashkernel=yes, reset kernel to new crashkernel value in the following two cases, - crashkernel=auto is found in the kernel cmdline - the kernel crashkernel was previously set by kexec-tools i.e. the kernel is using old default crashkernel value

To tell if the user is using a custom value for the kernel crashkernel or not, we assume the user would never use the default crashkernel value as custom value. When kexec-tools gets updated, 1. save the default crashkernel value of the older package to /tmp/crashkernel (for POWER system, /tmp/crashkernel_fadump is saved as well). 2. If auto_reset_crashkernel=yes, iterate all installed kernels. For each kernel, compare its crashkernel value with the old default crashkernel and reset it if yes

The implementation makes use of two RPM scriptlets [2], - %pre is run before a package is installed so we can use it to save old default crashkernel value - %post is run after a package installed so we can use it to try to reset kernel crashkernel

There are several problems when running kdumpctl in the RPM scripts for CoreOS/Atomic/Silverblue, for example, the lock can't be acquired by kdumpctl, "rpm-ostree kargs" can't be run and etc.. So don't enable this feature for CoreOS/Atomic/Silverblue.

Note latest shellcheck (0.8.0) gives false positives about the associative array as of this commit. And Fedora's shellcheck is 0.7.2 and can't even correctly parse the shell code because of the associative array.

[1] https://github.com/koalaman/shellcheck/issues/2399 [2] https://docs.fedoraproject.org/en-US/packaging-guidelines/Scriptlets/

Signed-off-by: Coiby Xu coxu@redhat.com --- kdumpctl | 35 +++++++++++++++++++++++++++++++++++ kexec-tools.spec | 15 +++++++++++++++ 2 files changed, 50 insertions(+)

diff --git a/kdumpctl b/kdumpctl index 412420d..a6582f8 100755 --- a/kdumpctl +++ b/kdumpctl @@ -1534,6 +1534,36 @@ reset_crashkernel() [[ $_reboot == yes && $_crashkernel_changed == yes ]] && reboot }

+# shellcheck disable=SC2154 # false positive when dereferencing an array +reset_crashkernel_after_update() +{ + local _kernel _crashkernel _dump_mode _fadump_val _old_default_crashkernel _new_default_crashkernel + declare -A _crashkernel_vals + + _crashkernel_vals[old_kdump]=$(cat /tmp/old_default_crashkernel 2> /dev/null) + _crashkernel_vals[old_fadump]=$(cat /tmp/old_default_crashkernel_fadump 2> /dev/null) + _crashkernel_vals[new_kdump]=$(get_default_crashkernel kdump) + _crashkernel_vals[new_fadump]=$(get_default_crashkernel fadump) + + for _kernel in $(_get_all_kernels_from_grubby); do + _crashkernel=$(get_grub_kernel_boot_parameter "$_kernel" crashkernel) + if [[ $_crashkernel == auto ]]; then + reset_crashkernel "--kernel=$_kernel" + elif [[ -n $_crashkernel ]]; then + _dump_mode=$(get_dump_mode_by_kernel "$_kernel") + _old_default_crashkernel=${_crashkernel_vals[old_${_dump_mode}]} + _new_default_crashkernel=${_crashkernel_vals[new_${_dump_mode}]} + if [[ $_crashkernel == "$_old_default_crashkernel" ]] && + [[ $_new_default_crashkernel != "$_old_default_crashkernel" ]]; then + _fadump_val=$(get_grub_kernel_boot_parameter "$_kernel" fadump) + if _update_grub "$_kernel" "$_new_default_crashkernel" "$_dump_mode" "$_fadump_val"; then + echo "For kernel=$_kernel, crashkernel=$_new_default_crashkernel now." + fi + fi + fi + done +} + if [[ ! -f $KDUMP_CONFIG_FILE ]]; then derror "Error: No kdump config file found!" exit 1 @@ -1599,6 +1629,11 @@ main() shift reset_crashkernel "$@" ;; + reset-crashkernel-after-update) + if [[ $(kdump_get_conf_val auto_reset_crashkernel) != no ]]; then + reset_crashkernel_after_update + fi + ;; *) dinfo $"Usage: $0 {estimate|start|stop|status|restart|reload|rebuild|reset-crashkernel|propagate|showmem}" exit 1 diff --git a/kexec-tools.spec b/kexec-tools.spec index ab7f41f..d72044a 100644 --- a/kexec-tools.spec +++ b/kexec-tools.spec @@ -258,6 +258,14 @@ chmod 755 $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99zz-fadumpini mkdir -p $RPM_BUILD_ROOT/%{dracutlibdir}/modules.d/ mv $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/* $RPM_BUILD_ROOT/%{dracutlibdir}/modules.d/

+%pre +if ! grep -q "ostree" /proc/cmdline && [ $1 == 2 ] && grep "get-default-crashkernel" /usr/bin/kdumpctl &>/dev/null; then + kdumpctl get-default-crashkernel kdump > /tmp/old_default_crashkernel 2>/dev/null +%ifarch ppc64 ppc64le + kdumpctl get-default-crashkernel fadump > /tmp/old_default_crashkernel_fadump 2>/dev/null +%endif +fi + %post # Initial installation %systemd_post kdump.service @@ -290,6 +298,13 @@ then /etc/sysconfig/kdump > /etc/sysconfig/kdump.new mv /etc/sysconfig/kdump.new /etc/sysconfig/kdump fi +if ! grep -q "ostree" /proc/cmdline && [ $1 == 2 ]; then + kdumpctl reset-crashkernel-after-update + rm /tmp/old_default_crashkernel 2>/dev/null || : +%ifarch ppc64 ppc64le + rm /tmp/old_default_crashkernel_fadump 2>/dev/null || : +%endif +fi

%postun

When kexec-tools updates the default crashkernel value, it will try to reset the existing installed kernels including the currently running kernel. So the running kernel could have different kernel cmdline parameters from /proc/cmdline. When installing a kernel after updating kexec-tools, /usr/lib/kernel/install.d/20-grub.install would be called by kernel-install [1] which would use /proc/cmdline to set up new kernel's cmdline. To address this special case, reset the new kernel's crashkernel and fadump value to the value that would be used by running kernel after rebooting by the installation hook. One side effect of this commit is it would reset the installed kernel's crashkernel even currently running kernel don't use the default crashkernel value after rebooting. But I think this side effect is a benefit for the user.

The implementation depends on kernel-install which run the scripts in /usr/lib/kernel/install.d passing the following arguments,

add KERNEL-VERSION $BOOT/MACHINE-ID/KERNEL-VERSION/ KERNEL-IMAGE [INITRD-FILE ...]

An concrete example is given as follows, add 5.11.12-300.fc34.x86_64 /boot/e986846f63134c7295458cf36300ba5b/5.11.12-300.fc34.x86_64 /lib/modules/5.11.12-300.fc34.x86_64/vmlinuz

kernel-install could be started by the kernel package's RPM scriplet [2]. As mentioned in previous commit "try to reset kernel crashkernel when kexec-tools updates the default crashkernel value", kdumpctl has difficulty running in RPM scriptlet fore CoreOS. But rpm-ostree ignores all kernel hooks, there is no need to disable the kernel hook for CoreOS/Atomic/Silverblue. But a collaboration between rpm-ostree and kexec-tools is needed [3] to take care of this special case.

Note the crashkernel.default support is dropped.

[1] https://www.freedesktop.org/software/systemd/man/kernel-install.html [2] https://src.fedoraproject.org/rpms/kernel/blob/rawhide/f/kernel.spec#_2680 [3] https://github.com/coreos/rpm-ostree/issues/2894

Signed-off-by: Coiby Xu coxu@redhat.com --- 92-crashkernel.install | 135 +---------------------------------------- kdumpctl | 31 ++++++++++ 2 files changed, 32 insertions(+), 134 deletions(-)

diff --git a/92-crashkernel.install b/92-crashkernel.install index 78365ff..1d67a13 100755 --- a/92-crashkernel.install +++ b/92-crashkernel.install @@ -5,142 +5,9 @@ KERNEL_VERSION="$2" KDUMP_INITRD_DIR_ABS="$3" KERNEL_IMAGE="$4"

-grub_etc_default="/etc/default/grub" - -ver_lt() { - [[ "$(echo -e "$1\n$2" | sort -V)" == $1$'\n'* ]] && [[ $1 != "$2" ]] -} - -# Read crashkernel= value in /etc/default/grub -get_grub_etc_ck() { - [[ -e $grub_etc_default ]] && \ - sed -n -e "s/^GRUB_CMDLINE_LINUX=.*(crashkernel=[^\ "]*)[\ "].*$/\1/p" $grub_etc_default -} - -# Read crashkernel.default value of specified kernel -get_ck_default() { - ck_file="/usr/lib/modules/$1/crashkernel.default" - [[ -f "$ck_file" ]] && cat "$ck_file" -} - -# Iterate installed kernels, find the kernel with the highest version that has a -# valid crashkernel.default file, exclude current installing/removing kernel -# -# $1: a string representing a crashkernel= cmdline. If given, will also check the -# content of crashkernel.default, only crashkernel.default with the same value will match -get_highest_ck_default_kver() { - for kernel in $(find /usr/lib/modules -maxdepth 1 -mindepth 1 -printf "%f\n" | sort --version-sort -r); do - [[ $kernel == "$KERNEL_VERSION" ]] && continue - [[ -s "/usr/lib/modules/$kernel/crashkernel.default" ]] || continue - - echo "$kernel" - return 0 - done - - return 1 -} - -set_grub_ck() { - sed -i -e "s/^(GRUB_CMDLINE_LINUX=.*)crashkernel=[^\ "]*([\ "].*)$/\1$1\2/" "$grub_etc_default" -} - -# Set specified kernel's crashkernel cmdline value -set_kernel_ck() { - kernel=$1 - ck_cmdline=$2 - - entry=$(grubby --info ALL | grep "^kernel=.*$kernel") - entry=${entry#kernel=} - entry=${entry#"} - entry=${entry%"} - - if [[ -z "$entry" ]]; then - echo "$0: failed to find boot entry for kernel $kernel" - return 1 - fi - - [[ -f /etc/zipl.conf ]] && zipl_arg="--zipl" - grubby --args "$ck_cmdline" --update-kernel "$entry" $zipl_arg - [[ $zipl_arg ]] && zipl > /dev/null ||: -} - case "$COMMAND" in add) - # - If current boot kernel is using default crashkernel value, update - # installing kernel's crashkernel value to its default value, - # - If intalling a higher version kernel, and /etc/default/grub's - # crashkernel value is using default value, update it to installing - # kernel's default value. - inst_ck_default=$(get_ck_default "$KERNEL_VERSION") - # If installing kernel doesn't have crashkernel.default, just exit. - [[ -z "$inst_ck_default" ]] && exit 0 - - boot_kernel=$(uname -r) - boot_ck_cmdline=$(sed -n -e "s/^.*(crashkernel=\S*).*$/\1/p" /proc/cmdline) - highest_ck_default_kver=$(get_highest_ck_default_kver) - highest_ck_default=$(get_ck_default "$highest_ck_default_kver") - - # Try update /etc/default/grub if present, else grub2-mkconfig could - # override crashkernel value. - grub_etc_ck=$(get_grub_etc_ck) - if [[ -n "$grub_etc_ck" ]]; then - if [[ -z "$highest_ck_default_kver" ]]; then - # None of installed kernel have a crashkernel.default, - # check for 'crashkernel=auto' in case of legacy kernel - [[ "$grub_etc_ck" == "crashkernel=auto" ]] && \ - set_grub_ck "$inst_ck_default" - else - # There is a valid crashkernel.default, check if installing kernel - # have a higher version and grub config is using default value - ver_lt "$highest_ck_default_kver" "$KERNEL_VERSION" && \ - [[ "$grub_etc_ck" == "$highest_ck_default" ]] && \ - [[ "$grub_etc_ck" != "$inst_ck_default" ]] && \ - set_grub_ck "$inst_ck_default" - fi - fi - - # Exit if crashkernel is not used in current cmdline - [[ -z $boot_ck_cmdline ]] && exit 0 - - # Get current boot kernel's default value - boot_ck_default=$(get_ck_default "$boot_kernel") - if [[ $boot_ck_cmdline == "crashkernel=auto" ]]; then - # Legacy RHEL kernel defaults to "auto" - boot_ck_default="$boot_ck_cmdline" - fi - - # If boot kernel doesn't have a crashkernel.default, check - # if it's using any installed kernel's crashkernel.default - if [[ -z $boot_ck_default ]]; then - [[ $(get_highest_ck_default_kver "$boot_ck_cmdline") ]] && boot_ck_default="$boot_ck_cmdline" - fi - - # If boot kernel is using a default crashkernel, update - # installing kernel's crashkernel to new default value - if [[ "$boot_ck_cmdline" != "$inst_ck_default" ]] && [[ "$boot_ck_cmdline" == "$boot_ck_default" ]]; then - set_kernel_ck "$KERNEL_VERSION" "$inst_ck_default" - fi - - exit 0 - ;; -remove) - # If grub default value is upgraded when this kernel was installed, try downgrade it - grub_etc_ck=$(get_grub_etc_ck) - [[ $grub_etc_ck ]] || exit 0 - - removing_ck_conf=$(get_ck_default "$KERNEL_VERSION") - [[ $removing_ck_conf ]] || exit 0 - - highest_ck_default_kver=$(get_highest_ck_default_kver) || exit 0 - highest_ck_default=$(get_ck_default "$highest_ck_default_kver") - [[ $highest_ck_default ]] || exit 0 - - if ver_lt "$highest_ck_default_kver" "$KERNEL_VERSION"; then - if [[ $grub_etc_ck == "$removing_ck_conf" ]] && [[ $grub_etc_ck != "$highest_ck_default" ]]; then - set_grub_ck "$highest_ck_default" - fi - fi - + kdumpctl reset-crashkernel-for-installed_kernel "$KERNEL_VERSION" exit 0 ;; esac diff --git a/kdumpctl b/kdumpctl index a6582f8..2979e1d 100755 --- a/kdumpctl +++ b/kdumpctl @@ -1564,6 +1564,32 @@ reset_crashkernel_after_update() done }

+reset_crashkernel_for_installed_kernel() +{ + local _installed_kernel _running_kernel _crashkernel _crashkernel_running + local _dump_mode_running _fadump_val_running + + if ! _installed_kernel=$(_find_kernel_path_by_release "$1"); then + exit 1 + fi + + if ! _running_kernel=$(_get_current_running_kernel_path); then + derror "Couldn't find current running kernel" + exit + fi + + _crashkernel=$(get_grub_kernel_boot_parameter "$_installed_kernel" crashkernel) + _crashkernel_running=$(get_grub_kernel_boot_parameter "$_running_kernel" crashkernel) + _dump_mode_running=$(get_dump_mode_by_kernel "$_running_kernel") + _fadump_val_running=$(get_grub_kernel_boot_parameter "$_kernel" fadump) + + if [[ $_crashkernel != "$_crashkernel_running" ]]; then + if _update_grub "$_installed_kernel" "$_crashkernel_running" "$_dump_mode_running" "$_fadump_val_running"; then + echo "kexec-tools has reset $_installed_kernel to use the new default crashkernel value $_crashkernel_running" + fi + fi +} + if [[ ! -f $KDUMP_CONFIG_FILE ]]; then derror "Error: No kdump config file found!" exit 1 @@ -1634,6 +1660,11 @@ main() reset_crashkernel_after_update fi ;; + reset-crashkernel-for-installed_kernel) + if [[ $(kdump_get_conf_val auto_reset_crashkernel) != no ]]; then + reset_crashkernel_for_installed_kernel "$2" + fi + ;; *) dinfo $"Usage: $0 {estimate|start|stop|status|restart|reload|rebuild|reset-crashkernel|propagate|showmem}" exit 1

Update crashkernel-howto since crashkernel.default has been removed. The documentation is also simplified as a result.

Signed-off-by: Coiby Xu coxu@redhat.com --- crashkernel-howto.txt | 123 +++++++----------------------------------- 1 file changed, 19 insertions(+), 104 deletions(-)

diff --git a/crashkernel-howto.txt b/crashkernel-howto.txt index 20f50e0..15768ab 100644 --- a/crashkernel-howto.txt +++ b/crashkernel-howto.txt @@ -13,13 +13,14 @@ kdump after you updated the `crashkernel=` value or changed the dump target. Default crashkernel value =========================

-Latest kernel packages include a `crashkernel.default` file installed in kernel -modules folder, available as: +Latest kexec-tools provides "kdumpctl get-default-crashkernel" to retrieve +the default crashkernel value,

- /usr/lib/modules/<kernel>/crashkernel.default + $ echo $(kdumpctl get-default-crashkernel) + 1G-4G:192M,4G-64G:256M,64G-102400T:512M

-The content of the file will be taken as the default value of 'crashkernel=', or -take this file as a reference for setting crashkernel value manually. +It will be taken as the default value of 'crashkernel=', you can use +this value as a reference for setting crashkernel value manually.

New installed system @@ -27,7 +28,7 @@ New installed system

Anaconda is the OS installer which sets all the kernel boot cmdline on a newly installed system. If kdump is enabled during Anaconda installation, Anaconda -will use the `crashkernel.default` file as the default `crashkernel=` value on +will use the default crashkernel value as the default `crashkernel=` value on the newly installed system.

Users can override the value during Anaconda installation manually. @@ -36,20 +37,11 @@ Users can override the value during Anaconda installation manually. Auto update of crashkernel boot parameter =========================================

-Following context in this section assumes all kernel packages have a -`crashkernel.default` file bundled, which is true for the latest official kernel -packages. For kexec-tools behavior with a kernel that doesn't have a -`crashkernel.default` file, please refer to the “Custom Kernel” section of this -doc. - -When `crashkernel=` is using the default value, kexec-tools will need to update -the `crashkernel=` value of new installed kernels, since the default value may -change in new kernel packages. - -kexec-tools does so by adding a kernel installation hook, which gets triggered -every time a new kernel is installed, so kexec-tools can do necessary checks and -updates. - +A new release of kexec-tools could update the 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 +crashkernel, you can change auto_reset_crashkernel to no in kdump.conf.

Supported Bootloaders --------------------- @@ -59,92 +51,13 @@ on `grubby`. If other boot loaders are used, the user will have to update the `crashkernel=` value manually.

-Updating kernel package ------------------------ - -When a new version of package kernel is released in the official repository, the -package will always come with a `crashkernel.default` file bundled. Kexec-tools -will act with following rules: - -If current boot kernel is using the default `crashkernel=` boot param value from -its `crashkernel.default` file, then kexec-tools will update new installed -kernel’s `crashkernel=` boot param using the value from the new installed -kernel’s `crashkernel.default` file. This ensures `crashkernel=` is always using -the latest default value. - -If current boot kernel's `crashkernel=` value is set to a non-default value, the -new installed kernel simply inherits this value. - -On systems using GRUB2 as the bootloader, each kernel has its own boot entry, -making it possible to set different `crashkernel=` boot param values for -different kernels. So kexec-tools won’t touch any already installed kernel's -boot param, only new installed kernel's `crashkernel=` boot param value will be -updated. - -But some utilities like `grub2-mkconfig` and `grubby` can override all boot -entry's boot params with the boot params value from the GRUB config file -`/etc/defaults/grub`, so kexec-tools will also update the GRUB config file in -case old `crashkernel=` value overrides new installed kernel’s boot param. - - -Downgrading kernel package --------------------------- - -When upgrading a kernel package, kexec-tools may update the `crashkernel=` value -in GRUB2 config file to the new value. So when downgrading the kernel package, -kexec-tools will also try to revert that update by setting GRUB2 config file’s -`crashkernel=` value back to the default value in the older kernel package. This -will only occur when the GRUB2 config file is using the default `crashkernel=` -value. - - -Custom kernel -============= - -To make auto crashkernel update more robust, kexec-tools will try to keep -tracking the default 'crashkernel=` value with kernels that don’t have a -`crashkernel.default` file, such kernels are referred to as “custom kernel” in -this doc. This is only a best-effort support to make it easier debugging and -testing the system. - -When installing a custom kernel that doesn’t have a `crashkernel.default` file, -the `crashkernel=` value will be simply inherited from the current boot kernel. - -When installing a new official kernel package and current boot kernel is a -custom kernel, since the boot kernel doesn’t have a `crashkernel.default` file, -kexec-tools will iterate installed kernels and check if the boot kernel -inherited the default value from any other existing kernels’ -`crashkernel.default` file. If a matching `crashkernel.default` file is found, -kexec-tools will update the new installed kernel `crashkernel=` boot param using -the value from the new installed kernel’s `crashkernel.default` file, ensures -the auto crashkernel value update won’t break over one or two custom kernel -installations. - -It is possible that the auto crashkernel value update will fail when custom -kernels are used. One example is a custom kernel inheriting the default -`crashkernel=` value from an older official kernel package, but later that -kernel package is uninstalled. So when booted with the custom kernel, -kexec-tools can't determine if the boot kernel is inheriting a default -`crashkernel=` value from any official build. In such a case, please refer to -the "Reset crashkernel to default value" section of this doc. - - Reset crashkernel to default value ==================================

kexec-tools only perform the auto update of crashkernel value when it can confirm the boot kernel's crashkernel value is using its corresponding default -value or inherited from any installed kernel. - -kexec-tools may fail to determine if the boot kernel is using default -crashkernel value in some use cases: -- kexec-tools package is absent during a kernel package upgrade, and the new - kernel package’s `crashkernel.default` value has changed. -- Custom kernel is used and the kernel it inherits `crashkernel=` value from is - uninstalled. - -So it's recommended to reset the crashkernel value if users have uninstalled -kexec-tools or using a custom kernel. +value and auto_reset_crashkernel=yes in kdump.conf. In other cases, the user +can reset the crasherknel value by themselves.

Reset using kdumpctl -------------------- @@ -152,12 +65,14 @@ Reset using kdumpctl To make it easier to reset the `crashkernel=` kernel cmdline to this default value properly, `kdumpctl` also provides a sub-command:

- `kdumpctl reset-crashkernel [<kernel version>]` + `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. +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.

Reset manually -------------- @@ -166,7 +81,7 @@ 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:

- grubby --update-kernel ALL --args "$(cat /usr/lib/modules/$(uname -r)/crashkernel.default)" + grubby --update-kernel ALL --args "$(kdumpctl get-default-crashkernel)"

Estimate crashkernel ====================