I am currently on the Gentoo-dist bin kernel and would like start compiling and customizing my own kernel, but I have never done anything like that before.
So here are my questions:
- What is the best way to start?
- Are there any good tools/scripts/etc that I should use?
- Is there anything I could/should do to protect myself for goofing up?
Thank you for your time!
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@rain
I haven't done it as I haven't needed to, but I've seen some stuff while hanging around gentoo places
1. Keep the dist-kernel around as a backup in case your manual kernel doesn't work
2. Follow the wiki
3. You can start with `make localmodconfig` to get a rough starting point of your current kernel's options and used modules
@rain The by far easiest way to do it, is to use the Distribution Kernel (not -bin) and then make use of your own config snippets.
This means that you don't have to maintain your own configuration from scratch, which is boring, tedious and it takes forever. You can instead just apply your own changes on top of the configuration from the Distribution Kernel project, which will override whatever settings they have set.
When it's looking pretty good, I run; `make -j$(nproc) && make modules_install && make install && dracut --kver <new version> (for LUKS encrypted storage - I'd prefer it if I could go without an initramfs of course) && grub-mkconfig -o /boot/grub/grub.cfg` and I see if it boots, otherwise I continue shotgun surgery.
Starting point is wiki. You can look at running gentoo-kernel-bin. lsmod will give some hints to what you must enable. The actual config depends on installed packages and your hardware.
I have a script to check what is missing in my kernel config.
pc ~ # cat `which emerge-check-kernel-config`
#!/bin/sh
if [[ -z "$1" ]]; then
echo "usage: $0 pkg"
exit 1
fi
pkg="$1"
path=$(equery w ${pkg})
result=$(awk '/CONFIG_/{print}' <(ebuild ${path} setup);)
ebuild ${path} clean
if [[ -n "${result}" ]]; then
echo ">>> ${pkg}"
echo "${result}"
fi
To check all installed packages.
pc ~ # cat `which emerge-check-kernel-config-all`
#!/bin/sh
if which rg &>/dev/null; then
rg -ls CONFIG_CHECK -g '*.ebuild' /var/db/pkg
else
grep -lr CONFIG_CHECK /var/db/pkg/
fi | cut -d'/' -f5-6 | parallel emerge-check-kernel-config {}
The result will be something like this.
pc ~ # emerge-check-kernel-config perf
>>> perf
* CONFIG_DEBUG_INFO: is not set when it should be.
* CONFIG_FTRACE: is not set when it should be.
* CONFIG_FTRACE_SYSCALLS: is not set when it should be.
* CONFIG_FUNCTION_TRACER: is not set when it should be.
* CONFIG_KALLSYMS_ALL: is not set when it should be.
* CONFIG_KPROBES: is not set when it should be.
* CONFIG_KPROBE_EVENTS: is not set when it should be.
* CONFIG_UPROBES: is not set when it should be.
* CONFIG_UPROBE_EVENTS: is not set when it should be.
Running emerge-check-kernel-config-all will take some time…
pc ~ # emerge-check-kernel-config-all
>>> dev-util/perf-6.7
* CONFIG_DEBUG_INFO: is not set when it should be.
* CONFIG_FTRACE: is not set when it should be.
* CONFIG_FTRACE_SYSCALLS: is not set when it should be.
* CONFIG_FUNCTION_TRACER: is not set when it should be.
* CONFIG_KALLSYMS_ALL: is not set when it should be.
* CONFIG_KPROBES: is not set when it should be.
* CONFIG_KPROBE_EVENTS: is not set when it should be.
* CONFIG_UPROBES: is not set when it should be.
* CONFIG_UPROBE_EVENTS: is not set when it should be.
# skiped
Don’t delete gentoo-kernel-bin. It’s a good fallback if something is broken in your custom kernel.
@rain While grabbing your current kernel's config and running "make localmodconfig" is a decent way, and I'd recommend using config snippets like @hund mentioned, I'd avoid those if you're looking into "learning to do it yourself".
Modern-day "make defconfig" doesn't need a *lot* of tweaking to get going, and you'll learn more about what you're actually enabling, what you're building into the kernel vs as a module, and etc. Read the gentoo handbook and the wiki pages for your graphics etc.