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  • Copyright CC BY-SA 4.0. See licensing for additional details
  • Author
  • Created 2015-05-23
  • Last updated: 2015-05-23
  • Changes
    • 2015-05-23: Initial creation

Kernel configurations

Common actions and configurations for setting up the kernel on Gentoo

Based on Configurations


  • Compare "make tinyconfig" to default hardend gentoo kernel config and see what else can be removed. Base kernel settings below on delta from tinyconfig to used config

Build Settings

  • Binary blobs1

    • Remove freedist from ACCEPT_LICENSE

      • /etc/portage/make.conf

    • Deblog kernel sources on extraction

      • /etc/portage/package.use

        # Deblob kernel sources
        sys-kernel/gentoo-sources deblob

Kernel settings

The linux kernel has a myriad of settings. Below are the settings that I either

  • make sure are turned on
  • turn off all the time
  • have selected based on the specified conditions

All other settings have been left on default

  • General setup
    • Local Version - YYYYMMDD-## where ## is one up number when building more than one version a day
    • Control Group Support
      • Freezer cgroup subsystem - built-in - required by app-emulation/docker
      • Device controller for cgroups - built-in - required by app-emulation/docker
      • Resource counters - built-in - Optional for Docker
        • Memory Resource Controller for Control Groups - built-in - for below dep
          • Memory Resource Controller Swap Extension - built-in - optional for app-emulation/docker
      • Enable perf_event per-cpu per-container group (cgroup) monitoring - built-in - optional for app-emulation/docker
      • Group CPU scheduler
        • Group scheduling for SCHED_OTHER
          • CPU bandwidth provisioning for FAIR_GROUP_SCHED - built-in - optional for app-emulation/docker
    • Initial RAM filesystem and RAM disk (initramfs/initrd) support
      • Initramfs source file(s): /usr/src/linux/initramfs/initramfs_list - Builds intramfs with the specified list
  • Processor type and features
    • Linux Guest support - CHOOSE: Enable if VM kernel, off otherwise
    • Supported processor vendors
      • Support Intel processors - CHOOSE if intel processor
      • Support AMD processors - CHOOSE if amd processor
      • Support Centaur processors
    • IBM Calgary IOMMU support
    • Intel MCE features - CHOOSE if intel processor
    • Dell laptop support
    • Intel microcode loading support - CHOOSE if intel processor
  • Power management and ACPI options
    • ACPI (Advanced Configuration and Power Interface) Support - built-in: Allow linux to control power
  • Bus options
    • PCCard (PCMCIA/CardBus) support
  • Networking support
    • Networking options
      • 802.1d Ethernet Bridging - module: required by app-emulation/docker
      • Network packet filtering framework (Netfilter)
        • Core Netfilter Configuration
          • Netfilter connection tracking support - Module: required by "IPv4 connection tracking support"
          • Netfilter Xtables support
            • "addrtype" address type match support - Module: required by app-emulation/docker
            • "conntrack" connection tracking match support - Module: required by app-emulation/docker
        • IP: Netfilter Configuration
          • IPv4 connection tracking support - Module: required by "IPv4 NAT"
          • IPv4 NAT - Module - required by app-emulation/docker
          • IP tables support
            • Packet filtering - Module: required by app-emulation/docker
            • iptables NAT suppoort
              • MASQUERADE target support - Module: required by app-emulation/docker
    • Wireless
  • Device Drivers
    • Generic Driver Options
      • Automount devtmpfs at /dev, after the kernel mounted the rootfs - built-in
    • Macintosh device drivers
    • Network Device support
      • Ethernet driver suppot
        • Realtek 8169 gigabit ethernet support - CHOOSE if realtek 8169 card
      • MAC-VLAN support - module: required by app-emulation/docker
      • Virtual ethernet pair device - module: required by app-emulation/docker
    • Input device support
      • Event interface - built-in: needed for Xorg
    • Character devices
      • Support multiple instances of devpts - ON - required by app-emulation/docker
    • Graphics Support
      • Direct Rendering Manger
        • Nouveau (nVidia) cards - CHOOSE if nVidia card
    • Sound Card support
      • Advanced Linux Sound Architecture
        • HD-Audio
          • Pre-Allocated buffer size for HD-audio driver - 2048 - recommend by media-sound/pulseaudio
    • Ultra Wideband devices
    • LED Support
    • Accessibility support
    • InfiniBand support
  • File Systems
    • The Extended 4 (ext4) filesystem -module: Not needed on boot
    • Reiserfs support -module: Not needed on boot
    • JFS filesystem support -module: Not needed on boot
    • XFS filesystem support -module: Not needed on boot
    • Btrfs filesystem support - built-in: btrfs used as primary filesystem
      • Btrfs POSIX Access Control Lists - built-in
      • Btrfs will run sanity tests upon loading - built-in
    • Quota support
    • Network File Systems
      • NFS client support
      • Ceph distributed file system - module: Going to be experimenting with ceph as backend
  • Library routines
    • PowerPC BCJ filter decoder
    • ARM BCJ filter decoder
    • ARM-Thumb BCJ filter decoder
    • SPARC BCJ filter decoder

Building an updated kernel

  • Make sure system is up to date

  • (Optional) If just rebuilding the existing version then backup just in case

    # Backup existing
    cd /usr/src
    # See current version
    ls -ld linux
    cp -a <CURRENT Kernel> <CURRENT Kernel>.YYYYMMDD
  • Select desired kernel

    eselect kernel list
    eselect kernel set 1
  • Start with current settings and update

    cd /usr/src/linux
    # Current running kernel config
    zcat /proc/config.gz > /usr/src/linux/.config
    # Accept defaults for any new kernel settings
    make oldconfig
    # Copy previous initramfs config to new kernel
    cp -a ../<PREVIOUS Kernel>/initramfs/ .
  • Build and install

    KERNELVER=#.##.# based on kernel being built
    EXTENSION=YYYMMDD-##      - Set to the value of "General setup | Local version" from kernel config
    make modules_prepare
    make && make modules_install
    cp .config /boot/config-${KERNELVER}-gentoo-gnu${EXTENSION}
    cp /boot/${KERNELVER}-gentoo-gnu${EXTENSION}
    cp arch/x86_64/boot/bzImage /boot/kernel-${KERNELVER}-gentoo-gnu${EXTENSION}
    grub2-mkconfig -o /boot/grub/grub.cfg
    cp -a .config ../${KERNELVER}-${EXTENSION}.config.bk


Multiple. “Binary Blob.” Wikipedia, the Free Encyclopedia, February 27, 2015.\&oldid=649060319Page Version ID: 649060319.

  1. Multiple, “Binary Blob.”