Comment 74 for bug 1926938

@Jens Glathe - Good stuff!

I wrote down some high-level steps in #32.

the mainline kernels from kernel.org have a lot of stuff disabled which will make things "fiddly". Easiest way to enable them for all the new hardware is to download the same mainline ubuntu kernel version even if it is broken. You just want the config in /boot.

copy that config for your version from the broken ubuntu mainline kernel /boot/ to your build path for the kernel with the same version.

e.g. here's the last one I did...
cp -v /boot/config-5.13.11-051311-generic ./linux-5.13.11/.config

where ./linux-5.13.11/ in the above example is the extracted folder from the tarball from kernel.org.

Then once you've got the config, you can delete the broken ubuntu mainline kernel.

With the ./linux-5.13.11/.config preconfigured. You may need to remove the debian certificates and configure for zstd. I don't use zstd and always disable it and change to xz since I have a lot of IoT devices with tiny storages and I get more breathing space with XZ. For an idea on how to do all these see #32 above

after all the config run
$ make olddefconfig

then you can then build.

For GCC-11 on my ivybridges it takes ~50mins
on my zen3 it takes 15mins.
on a skylake pentium it takes about 4 hours!