Linux

As a Linux user of almost 30 years, compiling hundreds of kernels over the years has given me a great appreciation of pre-build kernels, and a profound gratitude for those who package them up into convenient distros that work out of the box and let me get on with the rest of my life.

A wee bit of knowledge and the wisdom to stop doing it.

Back when I was still using Gentoo, configuring your own kernel was a rite of passage. It was kind of fun to try and configure it as minimalist as possible to cut down on the kernel compile time. Also, understanding all the different options and possibilities. And thanks to use flags, you had access to all these different patch sets for the kernel, which took a lot of the pain out of trying things like experimental schedulers or filesystems.

Bragging rights.

Better lzma performance with xz. 🤪

Years ago (2006-ish), I ran Gentoo on a 300mhz ultra low power system I used for an irc & web server. I gained LOTS of speed and lowered power draw even further while also enabling the hardware acceleration the board had for ssl encryption and video encoding. The whole thing would pull <5 watts and be super stable. It was well worth it.

But now days a Pi zero would trounce it in both low power draw and speed with stock kernels and I don’t really care enough to try to squeeze more out.

pain

I do it because I can... I read release notes on every update and once you've configured a kernel for a particular machine you really don't need to touch the config, barring major changes like when PATA and SATA merged. Or of course if I'm adding a new piece of hardware.

I remove everything I don't need and compiling the kernel only takes a couple minutes. I use Gentoo and approach everything on my system the same way - remove the things I don't need to make it as minimal as possible.

Compiling your own kernel also makes it easier when you need to do a git bisect to determine when a bug was introduced to report it or try to fix it. I've also included kernel patches in my build years ago, but haven't needed to do that in a long time.

I used to compile a custom kernel for my phone to enable modules/drivers that weren't included by default by the maintainer.

It's not about performance for me, it's about control.

I run linux-xanmod-anbox for root support in Waydroid (Android on Linux).

And I configured my kernel to support VFIO (Virtual Function Input Output).
So I can fully pass through one of my GPUs to my Ameliorated Windows KVM,
which I use for both work and gaming.

Mostly just understanding what was there, what was necessary for my machine at the time and what was optional.

I have configured custom Android kernel builds to enable more USB drivers, enable module support, and tweak various other things. For one tangible example of the result: I could plug in a USB Wi-Fi adapter and use it to simultaneously connect to another Wi-Fi network with the internal NIC while also sharing my own AP over USB. On an Android device of all things. I have also adjusted kernel builds for SBCs (like Pi clones) to get things working at all.

I have never seen any reason to configure a custom kernel for my own desktop/laptop systems. Default builds for the distros I've used have been fine for me; if I'm ever dissatisfied with anything it's the version number rather than the defconfig. The RHEL/Rocky kernel omits a few features I want (like btrfs) but I'd rather stick to other distros on personal systems than tweak a distro that isn't even meant for tweaking.

Just download the devel kernel from your distro and go into make menuconfig. I am on an Intel Laptop with recent hardware. No reason to use amd, nvidia etc drivers. And there is a shitload of likely unmaintained drivers for ancient hardware.

Knowledge and time forced to not be on the computer

I just installed LFS once, which inevitably came with compiling the kernel. Many times, over and over, every time with other configs as some packages required them. For a dual core Dell Laptop from the 2010 it was surprisingly fast, actually. Still not enjoyable or feasible for my normal systems.

I used to manually compile with the Linux-VServer patches, before Debian started shipping a pre-patched kernel.

Linux-VServer was kinda like LXC or OpenVZ. I was using it around 2008 or so as LXC wasn't quite ready for use in production yet (was still far from finished) and OpenVZ didn't support Debian hosts.

I suppose the most tangible benefit I get out of it is embedding a custom initramfs into the kernel and using it as an EFI stub. And I usually disable module loading and compile in everything I need, which feels cleaner. Also I make sure to tune the settings for my CPU and GPU, enable various virtualization options, and force SELinux to always remain active, among other things.

A kernel that fits my hardware and supports things the original kernel doesn't. Then again, i use gentoo.

I'm running a custom kernel on my Arch laptop. It's a little faster, a little smaller and a little quite more secure. I'm also running custom kernel which enables adiantum encryption on old phone with postmarketOS.