Static IP configuration for kdump

This document (7018592) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 11 Service Pack 4 (SLES 11 SP4)
SUSE Linux Enterprise Server 12 Service Pack 1 (SLES 12 SP1)
SUSE Linux Enterprise Server 12 Service Pack 2 (SLES 12 SP2)

Situation

Kdump was configured to use the static IP configuration from an eth* device.

As an example eth0 has been configured with a static IP address like this 192.168.1.1/24 and eth1 has been configured with a static IP address like this 10.50.50.100/20.

Kdump was configured to use the eth1 device with static configuration KDUMP_NETCONFIG in /etc/sysconfig/kdump:

KDUMP_CPUS=1
KDUMP_IMMEDIATE_REBOOT=yes
KDUMP_SAVEDIR=ftp://anonymous@10.50.50.140/crashdump/
KDUMP_KEEP_OLD_DUMPS=5
KDUMP_FREE_DISK_SIZE=64
KDUMP_VERBOSE=3
KDUMP_DUMPLEVEL=31
KDUMP_DUMPFORMAT=lzo
KDUMP_CONTINUE_ON_ERROR=yes
KDUMP_COPY_KERNEL=yes
KDUMP_NETCONFIG=eth1:static
KDUMP_NET_TIMEOUT=30

When testing the above configuration with

echo c>/proc/sysrq-trigger

kdump fails to reach the network which results in an error writing the kernel dump to the corresponding FTP location.

Resolution

In order to statically assign the IP address correctly to the kdump configuration the following line needs to be adjusted in /etc/sysconfig/kdump:

KDUMP_COMMANDLINE_APPEND=''

The following information needs to be added in order to achieve a static configuration.

KDUMP_COMMANDLINE_APPEND='ip=<dump client IP>:<dump server IP in this case the FTP server>:<gateway address>:<netmask>:<hostname>:<device>:<protocol>'

So in the above example the corresponding line would read:

KDUMP_COMMANDLINE_APPEND='ip=10.50.50.100:10.50.50.140:10.60.48.1:255.255.240.0:dump-client:eth1:none'

Cause

Even though the right netmask is set in the /etc/sysconfig/network/ifcfg-eth1 configuration file:

BOOTPROTO='static'
BROADCAST=''
ETHTOOL_OPTIONS=''
IPADDR='10.50.50.100/20'
MTU=''
NAME='e1000'
NETWORK=''
REMOTE_IPADDR=''
STARTMODE='auto'

leaving the KDUMP_COMMANDLINE_APPEND='' without a valid configuration for the static IP on eth1 kdump set's the netmask to /24 instead of /20.
This is the cause of the /usr/lib/dracut/modules.d/40network/ifup.sh script assuming that the IPv4 netmask is /24 because it can't find any valid static configuration in the /etc/sysconfig/kdump configuration.

As outlined in /etc/sysconfig/kdump you have to add the configuration to the KDUMP_COMMANDLINE_APPEND variable.

For static configuration, you have to add the configuration to KDUMP_COMMANDLINE_APPEND.

However the actual configuration was not documented here and a documentation update has been triggered internally to have this included in future documents.

Disclaimer

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