kernel.yml

- name: Install development tools
  package:
    name: "{{ item }}"
    state: installed
  loop: "{{ build_packages }}"

- name: Calculate kernel branch name for Amazon Linux 2
  set_fact:
    branch_name: "amazon-{{ ansible_kernel | regex_replace('^(?P<ver>\\d+.\\d+.)(?P<build>.*)', '\\g<ver>y/master') }}"
  when: ansible_facts["distribution_major_version"] == "2"

- name: Calculate kernel branch name for Amazon Linux 2023
  set_fact:
    branch_name: "amazon-{{ ansible_kernel | regex_replace('^(?P<ver>\\d+.\\d+.)(?P<build>.*)', '\\g<ver>y/mainline') }}" 
  when: ansible_facts["distribution_major_version"] == "2023"

- name: Clone source code for the current kernel
  git:
    repo: "https://github.com/amazonlinux/linux.git"
    version: "{{ branch_name }}"
    dest: "{{ build_dir }}"
    depth: 1

- name: Copy current config to the build dir
  copy:
    src: "/boot/config-{{ ansible_kernel }}"
    dest: "{{ build_dir }}/.config"
  
- name: Enable full tickless mode
  lineinfile:
    path: "{{ build_dir }}/.config"
    regexp: "^#\ CONFIG_NO_HZ_FULL.*$"
    line: "CONFIG_NO_HZ_FULL=y"

- name: Disable idle tickless mode
  lineinfile:
    path: "{{ build_dir }}/.config"
    regexp: "^CONFIG_NO_HZ_IDLE"
    line: "# CONFIG_NO_HZ_IDLE is not set" 

- name: Verify and fix the new config
  shell:
    cmd: "yes \"\" | make oldconfig"
    chdir: "{{ build_dir }}"

- name: Build a new kernel
  shell:
    cmd: "make -j {{ ansible_processor_vcpus }}"
    chdir: "{{ build_dir }}"

- name: Install modules
  shell:
    cmd: "make modules_install"
    chdir: "{{ build_dir }}"

- name: Get full version of the new kernel
  shell:
    cmd: "make kernelversion"
    chdir: "{{ build_dir }}"
  register: kernel_version

- name: Install kernel config
  copy:
    src: "{{ build_dir }}/.config"
    dest: "/boot/config-{{ kernel_version.stdout }}-{{ kernel_prefix }}"

- name: Install built kernel
  copy:
    src: "{{ build_dir }}/arch/{{ ansible_machine }}/boot/bzImage"
    dest: "/boot/vmlinuz-{{ kernel_version.stdout }}-{{ kernel_prefix }}"

- name: Generate initramfs
  shell:
    cmd: "dracut --hostonly --kver {{ kernel_version.stdout }}"
    chdir: "{{ build_dir }}"

- name: Add built kernel to GRUB
  shell:
    cmd: "grubby --grub2 --add-kernel=/boot/vmlinuz-{{ kernel_version.stdout }}-{{ kernel_prefix }} --title=\"Amazon Linux Tickless\" --initrd=/boot/initramfs-{{ kernel_version.stdout }}.img --copy-default"

- name: Set build kernel as default
  shell:
    cmd: "grubby --set-default=/boot/vmlinuz-{{ kernel_version.stdout }}-{{ kernel_prefix }}"

- name: Remove development tools
  package:
    name: "{{ item }}"
    state: absent
  loop: "{{ build_packages }}"
  
- name: Remove kernel source
  file:
    path: "{{ build_dir }}"
    state: absent