The kernel can be easily installed on a running system. During the boot process, the kernel is started with the latest version number by default. If you want to return to an old version, you can select the desired kernel version in the grub menu „Advanced options for Linux Mint“.

sudo apt install libncurses5-dev build-essential libssl-dev

Check here whether a patch is available for your currently installed kernel. If not, choose the next newer version and download the patch.

For example:
If you are running a 4.4.165 kernel choose the following patch:
patch-4.4.148-rt166-rc1.patch.gz

If you want to use a kernel version that is not already installed, please install the generic kernel with the correct version with this guide first.

• Clone the kernel

  git clone git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git

• Check out the same version as choosen for the patch

  git checkout -b RTPatch tags/v4.4.148

For RT-patch v4.4.148-rt166-rc1 install generic kernel 4.4.0

Instructions

• Go into the kenrel source directory
• Applay the patch

  cd <pathToKernelSrc>
  patch -p1 < <pathToPatch>/patch-4.4.148-rt166-rc1.patch

This selection will affect, how many modules will be built. The sizef and the range of functions of the monolitic kernel will not be changed. Additional modules can be built and installed after the kernel is installed.

• a.) Full module support (recommended) A normal Linux distribution, like Ubuntu, will install a kernel and most of the available kernel modules. Many of them are never used, because they are drivers for hardware, wich is not installed on the PC. This variant contains the same modules like a full Ubuntu kernel.
• b.) Minimal: This will only build modules which are essential. Some basic function like Wifi drivers may be missing. Some basic Ethernet drive are in the monolitic part of the kernel and will still work. You can add all modules you need manually.

1. Copy the kernel configuration from the generic kernel.
   • Make sure you copy the correct config-file with the correct version (i.e. config-4.4.0-040400-generic)

     cd <pathToKernelSrc>
     cp /boot/<yourDistributionConfig> ./.config

2. Applay the configuration to the patched kernel sources.

   make oldconfig

   • This will applay the configuration. However, since the kernel is patched and not identical to the generic kernel, not all configurations are defined. Acccept all presented options with ENTER.

1. Open the configuration menu

   make menuconfig

2. Enable the fully preemptible kernel (The path may be different depending on the kernel version)
   • Processor type and features —> Preemption Model /Voluntary Kernel Preemption (Desktop)) —> (X) Fully Preemptible Kernel (RT)
     • or
   • Kernel options —> Preemption Model (No Forced Preemption (Server)) —> (X) Fully Preemptible Kernel (RT)
3. Deactivate expert mode
   1. General setup —> [ ] Configure standard kernel features (expert users)
4. Save the configuration and exit the menu

This will going to take about an hour.

1. Compile kernel

   make -j8

2. Compile modules

   make modules -j8

3. Install kernel modules

   sudo make modules_install

4. Install kernel

   sudo make install

5. Reboot
6. Check with uname -a the kernel version