feat(kernel, kernel-headers): bump to 6.18.39.1 and enable TCP BBR3

[Rachel Menge (rlmenge)]

Summary

Bumps the Azure Linux kernel to 6.18.39.1 (from 6.18.31.1) and updates kernel-headers to match. BBR3 was added in this source update. Additionally, fork the kernel-headers to resolve the changelog and awkward overlays

Changes

kernel-headers forked to a local spec

• Migrated from spec = { type = "upstream" } + six overlays to spec = { type = "local", path = "kernel-headers.spec" }, matching the pattern already used by kernel.
• The Fedora upstream spec consumes a pre-built headers tarball and had increasing divergence (source swap, %build rewrite to make headers_install for native + cross arch, custom %{specrelease} scheme, static %changelog overlay). The delta had grown large enough that a maintained local spec is cheaper than tracking upstream through overlays.
• overlays/ and the generated kernel-headers.azl.macros are removed; %{kextraversion}/%{azl_pkgrelease} are inlined as %defines alongside the same discipline used by kernel.spec.

Kernel source bump — 6.18.31.1 → 6.18.39.1

• kernel.spec: source pin, %changelog.
• base/comps/kernel/6.18-{x86_64,aarch64}-azl.config: refreshed for the new source.

TCP BBR3 enabled as a module

• CONFIG_TCP_CONG_BBR3=m on x86_64 and aarch64.
• Recorded in scripts/ci/kernel/kernel-config-checker/.../azl4-os-required-kernel-configs.json since the option is now present in the upgraded source.

[Rachel Menge (rlmenge)]

/azp run

[azure-pipelines]

Azure Pipelines:
2 pipeline(s) were filtered out due to trigger conditions.

[Copilot]

Pull request overview

Updates the kernel stack to 6.18.39.1, enables BBR3, and converts kernel-headers to a local component spec.

Changes:

• Bumps kernel and kernel-headers sources to 6.18.39.1.
• Enables BBR3 as a module on x86_64 and ARM64.
• Replaces kernel-headers overlays with a local spec.

Reviewed changes

Copilot reviewed 20 out of 22 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
specs/k/kernel/sources	Updates rendered kernel source checksum.
specs/k/kernel/kernel.spec	Updates rendered version, release, and changelog.
specs/k/kernel/6.18-x86_64-azl.config	Enables BBR3 on x86_64.
specs/k/kernel/6.18-aarch64-azl.config	Refreshes ARM64 configuration and enables BBR3.
specs/k/kernel-headers/sources	Replaces headers archive with kernel source.
specs/k/kernel-headers/kernel-headers.spec	Renders the new local headers spec.
specs/k/kernel-headers/kernel-headers.azl.macros	Removes obsolete generated macros.
scripts/ci/kernel/kernel-config-checker/kernel_config_checker/kernel_configs_json/azl4-os-required-kernel-configs.json	Requires BBR3 modules on both architectures.
locks/kernel.lock	Refreshes the kernel input fingerprint.
locks/kernel-headers.lock	Converts the lock to local-spec inputs.
base/comps/kernel/sources	Pins the updated kernel archive.
base/comps/kernel/kernel.spec	Bumps the kernel version and release.
base/comps/kernel/kernel.comp.toml	Updates the kernel source declaration.
base/comps/kernel/6.18-x86_64-azl.config	Enables BBR3 on x86_64.
base/comps/kernel/6.18-aarch64-azl.config	Refreshes ARM64 configuration and enables BBR3.
base/comps/kernel-headers/overlays/0005-build-generate-native-cross.overlay.toml	Removes migrated build/install overlays.
base/comps/kernel-headers/overlays/0004-use-azl-kernel-tarball-source.overlay.toml	Removes the migrated source overlay.
base/comps/kernel-headers/overlays/0003-add-make-build-dependency.overlay.toml	Removes migrated dependency overlays.
base/comps/kernel-headers/overlays/0002-set-specrelease-kextraversion-pkgrelease.overlay.toml	Removes the migrated release overlay.
base/comps/kernel-headers/overlays/0001-set-specversion-3-part.overlay.toml	Removes migrated version overlays.
base/comps/kernel-headers/kernel-headers.spec	Adds the maintained local headers spec.
base/comps/kernel-headers/kernel-headers.comp.toml	Switches kernel-headers to the local spec.

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[Dan Streetman (ddstreetmicrosoft)]

a couple minor suggestions but overall LGTM

[Dan Streetman (ddstreetmicrosoft)]

suggestion(non-blocking):
upstream's specrelease is (e.g.) 100%{?buildid}%{?dist}. The %buildid is clearly intended to be used by uncommenting this macro define, and I don't think there's any reason that we should diverge from upstream on this - what do you think about adding %{?buildid} back into our specrelease macro (here and in the kernel spec)?

[Dan Streetman (ddstreetmicrosoft)]

suggestion(non-blocking):
if i'm reading both this and the kernel spec files correctly, this is identical to upstream's pkgrelease macro (and in the kernel spec, pkgrelease is simply set to %{azl_pkgrelease}).

To clarify this (and in the kernel spec), can you add a sentence to this macro's comment saying something like "This corresponds to upstream's %{pkgrelease} macro, and we use it in the %{specrelease} macro instead of a hardcoded value".
Or if you changed our macro to simply be pkgrelease then it would be easy to just state "we use this in the %{specrelease} macro instead of a hardcoded value"

also, another minor suggestion, i feel like the ordering of this macro and %kextraversion macro should be swapped, because %kextraversion is the "more significant" digit in the %specrelease macro. What do you think about moving the %azl_pkgrelease define to below the %kextraversion define?

[Dan Streetman (ddstreetmicrosoft)]

suggestion(non-blocking):
The comment is confusing here, as well as having a redundant explicit version number. What do you think of this text instead:

Our kernel source comes to us with a non-standard 4-digit version number (e.g. A.B.C.D), so we remove the 4th number (e.g. D) and use the standard 3-digit version (e.g. A.B.C), and place the 4th number into the leading (dot-separated) position of our release value, in the %specrelease macro below. For example, if kernel source is version "A.B.C.D", our rpm (and uname -r) V-R would start with "A.B.C-D." plus the remaining release macro/arch values.