[linuxftw]

Kernels without BTF data are ancient at this point. BTF was added in 4.18, that was in 2018. 2018! If you're running a kernel older than that, you don't need BPF, you need a whole new operating system.

Yes, each kernel version might have different features between then and now. You have to pick a minimum supported version and write against that.

[roblabla]

Many, many distributions didn't embed the BTF information until fairly recently. OpenSUSE did it in 15.4, released in 2023. At $WORK, we have many customers running on distros that didn't have embedded BTF - such as RHEL7 (yes, they pay for extended maintenance).

I really wish customers would update to a newer distro, but I also understand why they don't. So it's up to me to adapt.

> You have to pick a minimum supported version and write against that.

What we end up doing is progressively enabling features based on what's available in the kernel. Every eBPF we write is compiled multiple times with a couple of different flags to enable/disable certain features. It works decently well, and allows using the most capable datastructure/helpers based on the kernel version.

[magicalhippo]

We've got customers who complained when we bumped some critical dependencies and our software suddenly didn't work on Windows 2008 R2 servers any more... in 2025.

[_lvbh]

4.18? My uni still runs on 3.10…