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shodanshok
Asked: 2015-02-07 14:49:14 +0800 CST

Default kernel boot parameter on Red Hat 6 / CentOS 6

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I would like to understand if, and how, it is possible to configure default kernel boot parameters on Red Hat 6 / CentOS 6 (grub legacy bootloader).

I very well understand how to manually configure the required parameters: I simply have to edit /etc/grub.conf and edit the specific stanza. However, a similar configuration will not last a kernel update: the new stanza will be configured with default kernel boot parameters.

Newer system (eg: RHEL7) use grub2 and the /etc/default/grub file and the GRUB_CMDLINE_LINUX variable to solve that specific problem.

So my question is: it is possible to specify system-wide, default kernel boot parameters and let these parameters to be the default settings for new kernels (updated via YUM/RPM) also?

Thanks.

linux

1 Answers

  1. Best Answer

    New kernel will inherit kernel cmdline from the last running kernel, so if you make changes to grub.conf, they will persist kernel upgrade.

    You can see that by running:

    rpm -q --scripts kernel

    Relevant lines in RPM scripts are:

    NEWKERNARGS=""
(/sbin/grubby --info=`/sbin/grubby --default-kernel`) 2>/dev/null | grep -q crashkernel
if [ $? -ne 0 ]
then
        NEWKERNARGS="--kernel-args="crashkernel=auto""
fi

    So, only thing that RPM upgrade does is add crashkernel=auto if it's missing from kernel arguments.

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