Supported SBCs in mainline kernel

[Maffblaster]

Hello! Does anyone have a good resource to determine which SBCs are supported in the mainline Linux kernel? I would like to start surveying Gentoo's current support for embedded SBCs, however I don't want to use 3.x kernels for devices I may purchase (or be gifted??).

Once I get some hardware running, a short term goal would be to take another look at our Embedded Handbook and fix the long standing "ARM" handbooks problem (bug #534376 https://bugs.gentoo.org/534376). This will likely look like pointing those looking for an "installation handbook" to the Embedded Handbook, which then links to a small subset of 'supported' boards, and then a generic set of instructions after the boot environment (kernel, initramfs, and bootloader) has been properly configured.

The only boards I personally have running Gentoo right now is a RPI4 and a PineA64+. The A64+ kernel is running 3.10.102-2-pine64drm-longsleep. This is a much older kernel than I'd like it to be running. The Raspberry Pi foundation does a good job keeping their kernel at least up to the latest LTS, so my Pi's kernel is running 5.11.0-rc4-v8-rpi-5.11.y-p4.

As I understand, most SBCs have unique kernel (driver support and the need for certain kcmdline tweaks) and sometimes bootloader configurations to get them bootstrapped. After the userspace environment (base stage3) is running the rest of the Gentoo is about the same. Address me here if I'm wrong.

I'll keep doing research, but I'd like the community to weigh in on this... Honestly I'm quite new to the SBC/ARM scene, so I can take all the help that I can get.

I want this process of updating documentation to be as efficient as possible. Seems like one could spend hours searching one how to get all the bits necessary to boot a modern kernel. Multiply this on a per-board basis...

I haven't posted on the forums in a while, so looking forward to seeing your replies!
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[crocket]

Odroid N2 has a proprietary bootloader that is easy to install. Raspberry Pis have built-in bootloaders.

I tried compiling a bootloader for rockchip SBCs, and I gave up because it requires patched mainline kernels provided by armbian.

Armbian has its own build system that builds bootloaders and kernels for single board computers. I don't want to use an entire operating system's build system to build kernel and bootloaders.

I think documentation shouldn't cater to SBCs that make it difficult to compile and install bootloaders and kernels.