kernel: M2 earlycon build — full 6.18 zImage + minimal RV1106 board DT

M1 is complete (clk + pinctrl + mach compile clean); this reaches M2's build
milestone. multi_v7_defconfig + configs/m2-earlycon.fragment builds an 11.8 MB
zImage with clk-rv1106.o and pinctrl-rockchip.o (our rv1106 data) compiled into
the full tree — no rv1106 warnings. dts/rv1106-warden-m2.dts (CPU, GIC-400, arch
timer, 256 MiB RAM, GRF, the CRU, uart2 as snps,dw-apb-uart) compiles clean at
W=1 with earlycon=uart8250,mmio32,0xff4c0000. Reproducible via build-m2.sh.

Boot is the next step and is on-hardware/attended: package zImage + dtb, load on
a bench unit with a recovery net, watch for the earlycon "it's alive". PORT-VERIFY
before trusting a boot: DDR size/base, the CPU clock mux, console baud.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017wB8KB3MMQztRDXCMCkPrf

kernel/rv1106-enablement/build-m2.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# build-m2.sh — reproducible M2 (earlycon) build of the RV1106 → 6.18 forward-port.
+#
+# Produces: a zImage with our ported SoC drivers, and rv1106-warden-m2.dtb.
+# Boot is a separate on-hardware step (see PORT-STATUS.md "M2 boot").
+#
+# Usage:  KTREE=/path/to/linux-6.18.46 SDK_TC=/path/to/toolchain/bin ./build-m2.sh
+# Defaults match this workspace.
+set -euo pipefail
+
+FE="${FE:-<flare-edge>}"
+KTREE="${KTREE:-$FE/research/linux-6.18.46}"
+SDK_TC="${SDK_TC:-$FE/sdk/tools/linux/toolchain/arm-rockchip830-linux-uclibcgnueabihf/bin}"
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# The SDK toolchain bakes absolute paths and needs `python` (not python3) + a
+# space-free PATH (see the flare-edge-sdk-path-compat note).
+export PATH="$SDK_TC:/usr/bin:/bin"
+export ARCH=arm
+export CROSS_COMPILE=arm-rockchip830-linux-uclibcgnueabihf-
+
+[ -d "$KTREE" ] || { echo "kernel tree not found: $KTREE" >&2; exit 1; }
+command -v python >/dev/null || { echo "need 'python' on PATH (SDK quirk)" >&2; exit 1; }
+
+# Stage our board DT into the tree if it drifted from the capture.
+install -m664 "$HERE/dts/rv1106-warden-m2.dts" \
+    "$KTREE/arch/arm/boot/dts/rockchip/rv1106-warden-m2.dts"
+grep -q 'rv1106-warden-m2.dtb' "$KTREE/arch/arm/boot/dts/rockchip/Makefile" \
+    || sed -i 's/\trk3288-vyasa.dtb/\trk3288-vyasa.dtb \\\n\trv1106-warden-m2.dtb/' \
+       "$KTREE/arch/arm/boot/dts/rockchip/Makefile"
+
+cd "$KTREE"
+make ARCH=arm CROSS_COMPILE="$CROSS_COMPILE" multi_v7_defconfig
+./scripts/kconfig/merge_config.sh -m .config "$HERE/configs/m2-earlycon.fragment"
+make ARCH=arm CROSS_COMPILE="$CROSS_COMPILE" olddefconfig
+make ARCH=arm CROSS_COMPILE="$CROSS_COMPILE" -j"$(nproc)" zImage
+make ARCH=arm CROSS_COMPILE="$CROSS_COMPILE" rockchip/rv1106-warden-m2.dtb
+
+echo
+echo "== M2 build OK =="
+ls -la arch/arm/boot/zImage arch/arm/boot/dts/rockchip/rv1106-warden-m2.dtb