After Adding a New GRUB_CMDLINE_LINUX to /etc/default/grub System Is Not Booting as Expected

Applies To:

Oracle Linux 7 and Later

Symptoms:

A new GRUB_CMDLINE_LINUX line was added to enable "audit=1", in /etc/default/grub

After that, the boot change and the network configuration also changed. Serial console also stops working.

Cause:

In the file /etc/default/grub, only the last variable of each type is used, so if the configuration contains something like below, then only the last GRUB_CMDLINE_LINUX will be used.

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true
GRUB_DISABLE_RECOVERY="true" GRUB_ENABLE_BLSCFG=true
GRUB_TERMINAL="console"
GRUB_CMDLINE_LINUX="crashkernel=auto LANG=en_US.UTF-8 console=tty0 console=ttyS0,115200 rd.luks=0 rd.md=0 rd.dm=0 rd.lvm.vg=ocivolume rd.lvm.lv=ocivolume/root rd.net.timeout.carrier=5 netroot=iscsi:169.254.0.2:::1:iqn.2015-02.oracle.boot:uefi rd.iscsi.param=node.session.timeo.replacement_timeout=6000 net.ifnames=1 nvme_core.shutdown_timeout=10 ipmi_si.tryacpi=0 ipmi_si.trydmi=0 libiscsi.debug_libiscsi_eh=1 loglevel=4 ip=dhcp,dhcp6 rd.net.timeout.dhcp=10 crash_kexec_post_notifiers"
GRUB_CMDLINE_LINUX="audit=1"