Completing these steps requires in-depth Linux knowledge and is an advanced procedure.
If your Cent OS 5 server was provisioned prior to Dec 17 2010, then you are likely not running the latest Cent OS kernel and are missing many important security patches.
By using kexec you can upgrade your running Linux machine's kernel without a reboot.
Keep in mind, there's still a new kernel load, but it's significantly faster than doing the whole bootloader stage and hardware initialization phase performed by the system firmware (BIOS or UEFI). =================================================================================== Package Arch Version Repository Size =================================================================================== Installing: kernel x86_64 3.10.0-514.6.1.el7 updates 37 M So you have a couple of seconds of the new kernel load, for big physical machines with lots of RAM, this will be even more as the entire POST check can be skipped with this method. Thanks for promoting kexec (which is nothing new and is able to do what you have described for more than 7 years) but please update your article/video: Using kexec has nothing to do with “patching” a kernel. You are just restarting the OS (not the whole system! your are avoiding your system’s firmware (BIOS, now EFI) initializing including PXE boot, HW RAID, or other peripheral devices.
Kernel-ml also has the firmware, headers and libs files.
yum info kernel-ml Name : kernel-ml Arch : x86_64 Version : 4.11.1 Release : 1.el6.elrepo Size : 184 M Repo : installed From repo : elrepo-kernel Summary : The Linux kernel.