linux: build dtbs in parallel #106846
linux: build dtbs in parallel #106846
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I marked this as stale due to inactivity. → More info |
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This improves build speed, especially on machines with lots of cores such as the aarch64 community box and hydra builders.
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Rebased on current nixos-unstable-small. |
| @@ -56,6 +56,8 @@ let | |||
| # Dependencies that are required to build kernel modules | |||
| moduleBuildDependencies = optional (lib.versionAtLeast version "4.14") libelf; | |||
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| buildDTBs = stdenv.platform.kernelDTB or false; | |||
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had to delete this line and replace buildDTBs with kernelConf.DTB or false throughout to get a correct kernel with parallel dtb build. with that change applied it builds a functional pinebook pro kernel though.
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Ah, thanks for checking, I forgot to check if there were DTBs in the result 🤦 ! We should probably still use the buildDTBs variable, setting it to kernelConf.DTB or stdenv.platform.kernelDTB or false, in order to prioritise observable kernel config while falling back to the platform default and false otherwise.
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sounds good :D we've also just noticed that on the PBP at least there is no stdenv.platform.kernelDTB key, and kernelDTB does not seem to appear in the entirety of nixpkgs. there is stdenv.targetPlatform.linux-kernel.DTB though, did it get renamed in the almost-year since you opened this PR?
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Yes, presumably. or can be practical, but it can also obscure breakage due to renames… Will fix!
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I haven't been able to build this yet because my connection isn't super stable, but I've had a look at the nix-diff and it looks sensible.
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tested again: no kernel rebuild, so presumably still works. not sure about the config.isSet "DTB" though since there doesn't seem to be a DTB kconfig option. hardware.deviceTree exclusive uses stdenv.hostPlatform.linux-kernel.DTB to enable device tree support too, maybe that's the way to go?
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Sorry, got the definition completely wrong, I thoroughly misunderstood what you'd written at the beginning >_< fixed, episode 2. And it built with DTBs :)
Motivation for this change
Slightly faster builds, especially on aarch64 machines with lots of cores.
Things done
sandboxinnix.confon non-NixOS linux)