and apply at build time

Status

Accepted 2026-11-03 (owner, “1a 2a 3b”).

Until now the first-boot kernel was torvalds a804c57 plus config fragments only (kernel/*.config).
The first change that needs kernel source is a panel-edp entry for the mica panel (LGD 0x0804): without it the driver warns and uses fallback timings (panel-edp.c:755-772).
The kernel tree lives outside the repo (~/.cache/gbook/linux-a804c57, set up by scripts/setup-toolchain.sh), and the DTS scripts and check.sh read the same tree.

Patches are files in git: kernel/patches/NNNN-<topic>.patch, unified diffs against the pinned commit, each with a header saying what it changes, its source and whether it went upstream. Name order is apply order.
scripts/build-kernel.sh applies them before every build: it restores the files the patches touch from the pinned commit, fails if the tree has any other change, then runs git apply on each patch. The patches stay applied after the build, so the kernel release ends in -dirty.
check.sh check 20 fails when a patch no longer applies (or reverts) cleanly against the tree.
Upstream is a separate decision per patch. The first one (0001, panel-edp) stays local: the EDID gives only part of the model name (“LP134WQ…”), and an upstream entry needs the full name.

The pinned tree is no longer pristine after a build; git -C ~/.cache/gbook/linux-a804c57 status shows the patched files. Running build-kernel.sh again is safe, and any foreign edit stops it.
Moving the pin (ADR 0004) means re-checking every patch; check 20 shows which ones break.

Owner: “all a” to question 5 of milestones-versioning.md, section 5.

Line 1 of every patch reads Status: <WORD> <reference>. The words are ChromiumOS’s patch-tagging words, with LOCAL in place of its CHROMIUM and no BACKPORT (a modified copy says so in its reference):
- LOCAL <who>: carried downstream and not posted to a list (gbook’s own, or a third party’s downstream fix-up);
- FROMLIST <list reference>: posted to a list, not in a maintainer tree when checked;
- FROMGIT <tree> <branch>: in a maintainer or -next tree, not in mainline;
- UPSTREAM <tag or commit>: in mainline, a backport onto the pin.
A lore Message-ID goes in the reference when one is known, and the line says “not recorded” otherwise. The free-text header below the line stays. git apply ignores everything before the first diff, so check 20 is unaffected.
A patch number is never reused. A deleted patch’s number is retired, and the next patch takes the next unused number. Two numbers were reused before this rule:
- 0008 first named a GENI I2C timing patch (16a2828) and now names the PCIe GDSC patch;
- 0009 first named the IRQ-to-CPU-1 diagnostic (cee735d, deleted by ADR 0009) and now names the PCIe PHY GDSC patch.
The new patches arrived on 2026-11-04 (5272658 at 4:07 AM ET and ddecbd8 at 4:47 AM ET). A log entry older than those commits that says “0008” or “0009” means the old patch.
check.sh check 34 enforces both rules. It allows exactly those two old reuses.