iter6 v3: stage KCSAN-only config delta script for second-pass build

KASAN and KCSAN are mutually exclusive on 7.0-rc3 kernel
(lib/Kconfig.kcsan: 'depends on ... !KASAN'). User picked
KASAN first. This script applies the KCSAN-only config delta
on top of the lockdep base for the follow-up build, so the
KCSAN config survives session-compacting.

Run AFTER the KASAN-pass test cycle completes, IF KASAN comes
up silent on the GPU-compositor wedge test.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

iter6_v3_kcsan_config_delta.sh

@@ -0,0 +1,38 @@
+#!/bin/bash
+# iter6 v3 second-pass: KCSAN-only kernel build (if KASAN-pass comes up silent)
+#
+# Run AFTER the KASAN-pass build/install/test cycle is complete.
+# This script applies the KCSAN config delta on top of the lockdep base.
+# KCSAN is mutually exclusive with KASAN on this kernel
+# (lib/Kconfig.kcsan: depends on ... !KASAN).
+#
+# Usage: cd ~/src/linux-rockchip && bash /path/to/this/script
+
+set -e
+cd "$(dirname "$(readlink -f "$0")")"
+[[ -f Makefile ]] || cd ~/src/linux-rockchip
+
+echo "=== restore lockdep config (pre-kasan baseline) ==="
+[[ -f .config.pre-iter6v3-kasan ]] && cp .config.pre-iter6v3-kasan .config
+echo
+echo "=== apply KCSAN-only config delta ==="
+./scripts/config --disable KASAN --disable KASAN_GENERIC --disable KASAN_OUTLINE \
+                 --disable KASAN_STACK --disable KASAN_VMALLOC \
+                 --enable KCSAN --enable KCSAN_VERBOSE \
+                 --set-val KCSAN_REPORT_ONCE_IN_MS 2000 \
+                 --enable KCSAN_REPORT_VALUE_CHANGE_ONLY \
+                 --enable DEBUG_PREEMPT --enable DEBUG_ATOMIC_SLEEP \
+                 --enable DEBUG_OBJECTS --enable DEBUG_OBJECTS_RCU_HEAD \
+                 --enable DEBUG_LIST \
+                 --enable SLUB_DEBUG --enable SLUB_DEBUG_ON \
+                 --enable PAGE_POISONING \
+                 --set-str LOCALVERSION "-lockdep-kcsan"
+make olddefconfig
+grep -E "^CONFIG_(KASAN|KCSAN)" .config | head
+echo
+echo "=== verify mutex with KASAN ==="
+if grep -q "^CONFIG_KASAN=y" .config; then
+    echo "ERROR: KASAN still =y — KCSAN won't enable. Fix .config manually."
+    exit 1
+fi
+echo "=== KCSAN build can proceed with: time pump make -j8 CC='distcc gcc' Image modules dtbs ==="