kernel_cfg.sh

Simple script to generate linux kernel config file. Known working environment: gentoo

License: GPL-3+

Gentoo Forum thread: https://forums.gentoo.org/viewtopic-t-1090188.html

How kernel_cfg.sh script works

1. Basically there is an assumption the kernel developers does set useful default values. The kernel-tree config file arch/x86/configs/*_defconfig or provided distro config files in kernel_cfg/distro can be used as starting base.

2. The provided configuration modifiers cfg/*.config contains the additional settings and is able to override the defconfig values. It is possible to enhance the configuration by own files placed in cfg folder. If you create own files, please contribute them to the project if useful for other users.

3. At the next the files are just concatenated. To get proper config file the make olddefconfig is called.

Howto install

In Gentoo the sys-kernel/kernel-cfg package is available in bell07 overlay.

Without gentoo just checkout the repo and call the scripts from project directory.

How to use

1. Backup your current /usr/src/linux/.config config file
2. Create settings.env from example
3. Choose your base configuration CFG_DEFCONFIG="??.config" (archlinux, gentoo-genkernel, gentoo-fedora-x86_64 or kernel-provided defconfig) in settings.env to your preferred one.
4. Check which configuration modules in cfg folder you need. Adjust the CFG_MODULES in settings.env
5. If you know additional settings you need, create new 99* files (like cfg/99_my_settings.config )
6. run kernel_cfg.sh
7. Check the config comparing with your backup. Hint: for easier comparing the files could be sorted ;-)
8. Create issue in case of issues or new usefull pre-setting
9. Build and install the kernel using kernel_build.sh
10. Reboot and and enjoy

Gentoo ebuild notes

The settings.env is installed into /etc/kernel-cfg.env All cfg snippets are installed into /etc/kernel/config.avail The snippets can be activated by eselect kernel-cfg in /etc/kernel/config.d". Therefore the CFG_PATH="/etc/kernel/config.d" and CFG_MODULES="*" are the right settings. build from sys-kernel/*sources can be done using kernel_cfg.sh and kernel_build.sh like described above.

The sys-kernel/gentoo-kernel provides own build magic and own base configuration. Therefore the /etc/kernel-cfg.env file and bash scripts are not used in this scenario. However, the configuration snippets are used with the sys-kernel/gentoo-kernel, if selected by eselect kernel-cfg. In short:

• Select modules by eselect kernel-cfg.
• emerge gentoo-kernel uses the selected snippets in /etc/kernel/config.d and same source like gentoo-fedora-x86_64.config for the configuration base.

# ls -l /etc/kernel/config.d/
insgesamt 4
lrwxrwxrwx 1 root root  42  4. Jan 08:36 00_defaults.config -> /scripts/kernel_cfg/cfg/00_defaults.config
lrwxrwxrwx 1 root root  57  4. Jan 08:35 10_disable_all_net_vendors.config -> /scripts/kernel_cfg/cfg/10_disable_all_net_vendors.config
lrwxrwxrwx 1 root root  54  4. Jan 08:35 10_disable_misc_options.config -> /scripts/kernel_cfg/cfg/10_disable_misc_options.config
lrwxrwxrwx 1 root root  55  4. Jan 08:36 20_enable_boot_nvme_root.config -> /scripts/kernel_cfg/cfg/20_enable_boot_nvme_root.config
-rw-r--r-- 1 root root 524  3. Nov 17:38 99_my_hardware.config

Please note, since the fedora based gentoo-kernel base configuration does have the most settings enabled by default, the most 30* and 50* snippets are redundant.

Enhanced usage

The kernel_cfg can handle different profiles using different settings.env files. Just call the kernel_cfg with the other env file as parameter ./kernel_cfg config_second.env. I recommend to utilize CONFIG_LOCALVERSION for different kernels in custom config snippet. Set the "KERNEL_LOCALVERSION" parameter in second setting.env file to adjust the CONFIG_LOCALVERSION.

If the distro config is not uptodate, the script get_distro_defaults.sh can be used for update. Please create issue on github

The update_disable.sh script check for new entries for 10_disable_all_*.config files. The script generates new *.tmp files for manually merge/update. Please backup your /usr/src/linux/.config before run, because the script calls make allmodconfig to get full settings list.

Configuration files

File(s)	Use-case
Default settings
00_defaults.config	Default configuration adjustments that should be in any kernel. Some parameters are overriden in next settings files
01_gentoo*.config	Gentoo base defaults from https://github.com/projg2/gentoo-kernel-config and used in sys-kernel/gentoo-kernel ebuild. No need to enable if the ebuild is used.
10_disable_*.config	Disable stuff to get the kernel smaller by default. Useful for non-universal kernels bound to a hardware. Some parameters are re-activated in other config files.
Enable boot capability without inintramfs
20_enable_boot_mmc_sdhci_root.config	Boot from SSD type MMC on PCI Secure Digital Host Controller (SDHCI_PCI)
20_enable_boot_nvme_root.config	Boot from NVMe SSD
20_enable_boot_usb_root.config	Boot from USB storage disk
Additional Hardware
30_enable_amd_device.config	Enable usual AMD hardware (amd kvm, amd iommu ...)
30_enable_intel_device.config	Enable usual intel hardware (realtek lan, intel wifi, intel kvm, intel iommu ...)
30_enable_steamdeck_device.config	Hardware related configurations for Valve's Steam Deck handheld
Services support	useful if you like to run this services
50_docker.config	Docker server support
50_lxc.config	LXC server support
50_virtualbox_guest.config	All required configuration needed for Virtualbox guest
50_vmware_guest.config	All required configuration needed for Vmware guest
50_waydroid_host.config	Settings required to run waydroid
Custom	Additional configuration
99_*.config	It's yours! The files are ignored by git. Create your own settings