I found an interesting problem. After yum update, the kernel install run out error. After the reboot i received kernel panic.
Solution:
1. Start the linux with the old kernel.
2. Create new initramfs with the following steps:
2.1 Create intirams:
dracut -f -v --kver <kernel> (example: 3.10.0-693.11.6.el7.x86_64)
2.2 Update grub2:
grub2-mkconfig -o /boot/grub2/grub.cfg
2.3 Check the grub2 config:
grep initrd /etc/grub2.cfg set tuned_initrd="" initrd16 /initramfs-3.10.0-693.11.6.el7.x86_64.img initrd16 /initramfs-3.10.0-514.6.1.el7.x86_64.img initrd16 /initramfs-3.10.0-514.el7.x86_64.img
grep "menuentry " /boot/grub2/grub.cfg
menuentry 'Red Hat Enterprise Linux Server (3.10.0-693.11.6.el7.x86_64) 7.4 (Maipo)' --class red --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-693.11.6.el7.x86_64-advanced-dad5925c-4696-4338-bfd0-fa82090398b1' {
menuentry 'Red Hat Enterprise Linux Server (3.10.0-514.6.1.el7.x86_64) 7.4 (Maipo)' --class red --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-514.6.1.el7.x86_64-advanced-dad5925c-4696-4338-bfd0-fa82090398b1' {
menuentry 'Red Hat Enterprise Linux Server (3.10.0-514.el7.x86_64) 7.4 (Maipo)' --class red --class gnu-linux --class gnu --class os --unrestricted $menuentry_id_option 'gnulinux-3.10.0-514.el7.x86_64-advanced-dad5925c-4696-4338-bfd0-fa82090398b1' {
2.3. Set the default to your new kernel:
awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg
0 : Red Hat Enterprise Linux Server (3.10.0-693.11.6.el7.x86_64) 7.4 (Maipo)
1 : Red Hat Enterprise Linux Server (3.10.0-514.6.1.el7.x86_64) 7.4 (Maipo)
2 : Red Hat Enterprise Linux Server (3.10.0-514.el7.x86_64) 7.4 (Maipo)
grub2-set-default 0 grub2-editenv list saved_entry=0
3.1 Reboot:
reboot or shutdown -r now
3.2 Check your kernel version:
uname -a
