On Fri, Jul 18, 2014 at 04:14:01PM +0800, WANG Chao wrote:
Now upon failure kdump script might not be called at all and it
might
not be able to execute default action. It results in a hang.
Because we disable emergency shell and rely on kdump.sh being invoked
through dracut-pre-pivot hook. But it might happen that we never call
into dracut-pre-pivot hook because certain systemd targets could not
reach due to failure in their dependencies. In those cases error
handling code does not run and system hangs.
To solve this problem, we need to separate the error handling code from
dracut-pre-pivot hook, and every time when a failure shows up, the
separated code can be called by the emergency service.
By default systemd provides an emergency service which will drop us into
shell every time upon a critical failure. It's very convenient for us to
re-use the framework of systemd emergency, because we don't have to
touch the other parts of systemd. We can use our own script instead of
the default one.
This new scheme will overwrite emergency shell and replace with kdump
error handling code. And this code will do the error handling as needed.
Now, we will not rely on dracut-pre-pivot hook running always. Instead
whenever error happens and it is serious enough that emergency shell
needed to run, now kdump error handler will run.
Signed-off-by: WANG Chao <chaowang(a)redhat.com>
---
dracut-kdump-emergency.service | 23 +++++++++++++++++++++++
dracut-kdump-error-handler.sh | 10 ++++++++++
dracut-module-setup.sh | 3 +++
kexec-tools.spec | 5 ++++-
4 files changed, 40 insertions(+), 1 deletion(-)
create mode 100644 dracut-kdump-emergency.service
create mode 100755 dracut-kdump-error-handler.sh
diff --git a/dracut-kdump-emergency.service b/dracut-kdump-emergency.service
new file mode 100644
index 0000000..6c90420
--- /dev/null
+++ b/dracut-kdump-emergency.service
@@ -0,0 +1,23 @@
+[Unit]
+Description=Kdump Error Handler
+DefaultDependencies=no
+After=systemd-vconsole-setup.service
+Wants=systemd-vconsole-setup.service
+
+[Service]
+Environment=HOME=/
+Environment=DRACUT_SYSTEMD=1
+Environment=NEWROOT=/sysroot
+WorkingDirectory=/
+ExecStart=/bin/kdump-error-handler.sh
+ExecStopPost=-/usr/bin/systemctl --fail --no-block default
+Type=oneshot
+StandardInput=tty-force
+StandardOutput=inherit
+StandardError=inherit
+KillMode=process
+IgnoreSIGPIPE=no
Hi Chao,
I am thinking more about the licence of this file. We have practically
taken this file from emergency.service of dracut. And in dracut tree
that file has following header.
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published
# by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
# See systemd.special(7) for details
I guess either we should send a mail to systemd folks and ask about
licensing. That is if we copy and modify a unit file, what kind of
copyright needs to be attributed and what kind of licensing info
needs to be retained.
My feeling is that to be safe, let us retain that header.
Thanks
Vivek