Those who custom configure their kernel: what did you gain?
Curious to know the coolest things you achieved by configuring your kernel. I know kernel config can be boring, but I’m hoping someone will have an impressive answer.
For me I have a very lightweight kernel that runs wayland on nvidia without any issues to date.
Not for myself but a client who was running a game server. He wanted to tweak the number of ticks/second that the kernel interacted with CPU. Didn’t even know that this was a parameter and after a few attempts, according to him, never went on that server myself, made a huge difference and he claimed having grabbed a good part of the market because of that.
After that familiarized myself more with the stuff in there. But that was a good while ago, before most of you guys were born.
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.
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.
The secureblue image I use disables numerous kernel modules, and enables many kernel mitigation argument.
The performance impact is minimal, hopefully that means a more secure system? I honestly don’t know, nor do I change the default recommended by the developer.
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.
I’m playing around with coreboot and that gives me ability to embed Linux kernel. The problem is we’re limited by the amount of ROM chip which is between 4MiB to 16MiB depending on the specific device. The one I’m working on got 12MiB, about 3 is taken in order to boot normally, leaving me with 9 to play around.
Enter buildroot, (arguably) a Linux distro that allows you to have kernel, busybox, minimum libc, along with whatever software you’d choose.
While it’s easy to include only what’s needed to have a working system (busybox provides working shell as well as the coreutils), you’d need to get rid of stuff you don’t need, such as drivers for hardware you wouldn’t have.
Aside from that, you’d end up with better running kernel in general if you know what you’re doing. I run Gentoo and have kept a working config that I tweak from time to time (especially on version upgrade).
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.
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.
Customising the kernel just means something works properly in rare hardware configurations like you described. It’s something which he who uses the general hardware (like an X86 desktop) can’t easily see or understand because the ‘stock’ kernel is already working properly.
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