Re: [PATCH v2] kdumpctl: eliminate redundant lsinitrd in dracut

[Xunlei Pang]

On 05/09/2017 at 01:51 PM, Ziyue Yang wrote:
>  Currently in Fedora/RedHat dracut installs its fedora.conf.example
>  as the default config file, in which sysloglvl is set 5. This leads
>  to maxloglvl=5 in dracut calls, making unnecessary lsinitrd calls
>  during initramfs builds.
>
>  This patch makes use of --conf and --confdir arguments of dracut,
>  creates temp config directory before mkdumprd(dracut) calls. It
>  appends sysloglvl=0 option by creating a 99-kdumpctl.conf file in
>  the temp config directory.
>
>  1) Before this patch
>  $ kdumpctl stop; touch /etc/kdump.conf; time kdumpctl start
>  kexec: unloaded kdump kernel
>  Stopping kdump: [OK]
>  Detected change(s) in the following file(s):
>    /etc/kdump.conf
>  Rebuilding /boot/initramfs-4.10.10-200.fc25.x86_64kdump.img 4.10.10-200.fc25_x86_64
>  kexec: loaded kdump kernel
>  Starting kdump: [OK]
>  real    0m18.716s
>  user    0m13.863s
>  sys     0m3.269s
>
>  2) After this patch
>  $ kdumpctl stop; touch /etc/kdump.conf; time kdumpctl start
>  kexec: unloaded kdump kernel
>  Stopping kdump: [OK]
>  Detected change(s) in the following file(s):
>    /etc/kdump.conf
>  Rebuilding /boot/initramfs-4.10.10-200.fc25.x86_64kdump.img 4.10.10-200.fc25_x86_64
>  kexec: loaded kdump kernel
>  Starting kdump: [OK]
>  real    0m13.665s
>  user    0m10.945s
>  sys     0m2.907s
>
>  Signed-off-by: Ziyue Yang <ziyang(a)redhat.com&gt;
>  ---
>   kdumpctl | 16 +++++++++++++++-
>   1 file changed, 15 insertions(+), 1 deletion(-)
>
>  diff --git a/kdumpctl b/kdumpctl
>  index 4d6b3e8..a37db01 100755
>  --- a/kdumpctl
>  +++ b/kdumpctl
>  @@ -5,7 +5,6 @@ KDUMP_KERNELVER=""
>   KDUMP_COMMANDLINE=""
>   KEXEC_ARGS=""
>   KDUMP_CONFIG_FILE="/etc/kdump.conf"
>  -MKDUMPRD="/sbin/mkdumprd -f"
>   SAVE_PATH=/var/crash
>   SSH_KEY_LOCATION="/root/.ssh/kdump_id_rsa"
>   INITRD_CHECKSUM_LOCATION="/boot/.fadump_initrd_checksum"
>  @@ -20,6 +19,18 @@ DEFAULT_DUMP_MODE="kdump"
>   image_time=0
>   
>   [[ $dracutbasedir ]] || dracutbasedir=/usr/lib/dracut
>  +
>  +# lower dracut's default sysloglvl to speedup initramfs build
>  +DRACUT_SYSLOGLVL="3"
>  +# make temp dir for dracut conf files
>  +[[ $dracutconfdir ]] || dracutconfdir=/tmp/kdumpctl.dracut.conf
>  +mkdir -p $dracutconfdir/dracut.conf.d
>  +[[ -e $dracutbasedir/dracut.conf.d ]] && cp -rf $dracutbasedir/dracut.conf.d
> $dracutconfdir/
>  +[[ -e $dracutbasedir/dracut.conf ]] && cp -rf $dracutbasedir/dracut.conf
> $dracutconfdir/
>  +echo "sysloglvl=$DRACUT_SYSLOGLVL" >
> $dracutconfdir/dracut.conf.d/99-kdumpctl.conf
>  +
>  +MKDUMPRD="/sbin/mkdumprd --conf $dracutconfdir/dracut.conf --confdir
> $dracutconfdir/dracut.conf.d -f" 
According to /usr/bin/dracut implementation:
    if [[ ! -d $confdir ]]; then
        if [[ $allowlocal ]]; then
            confdir="$dracutbasedir/dracut.conf.d"
        else
            confdir="/etc/dracut.conf.d"
        fi
    fi

    # source our config file
    [[ -f $conffile ]] && . "$conffile"

    # source our config dir
    for f in $(dropindirs_sort ".conf" "$confdir"
"$dracutbasedir/dracut.conf.d"); do
        [[ -e $f ]] && . "$f"
    done

So, "$dracutbasedir/dracut.conf.d" is always sourced, looks like it suffices to
create one
kdump config file(say 99-kdump-loglevel.conf, "99" will override the others)
with pre-defined
log levels(like sysloglvl=3, stdloglvl=3, etc),  then pass it to dracut with
"--conf".

We also can place the file under "/etc/dracut.conf.d/" or
"/usr/lib/dracut/dracut.conf.d/"
directly when kexec-tools rpm is installed via kexec-tools.spec.

What do you think?

Regards,
Xunlei

>  +
>   . $dracutbasedir/dracut-functions.sh
>   . /lib/kdump/kdump-lib.sh
>   
>  @@ -284,6 +295,9 @@ rebuild_initrd()
>   		rebuild_kdump_initrd
>   	fi
>   
>  +	# delete tmp conf folder for dracut
>  +	rm -rf /tmp/kdumpctl.dracut.conf
>  +
>   	return $?
>   }
>