Add script to check HOME segment start address

Makefile

@@ -26,6 +26,7 @@ VERSION?=$(DATE)_$(REV)
 # Default target - build the board's EC firmware
 all: $(BUILD)/ec.rom
 	$(info Built $(VERSION) for $(BOARD))
+	./scripts/check-home-segment.sh
 
 # Include common source
 COMMON_DIR=src/common

scripts/check-home-segment.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-3.0-only
+
+# SDCC 4.5.0 will incorrectly move the HOME segment, which contains the
+# compiler-generated interrupt vector table, to code address 0x50 with ITE
+# chips that declare the 16-byte signature at the default address of 0x40.
+#
+# Ref: https://github.com/system76/ec/issues/518
+
+BUILD_DIR="${BUILD_DIR:-build}"
+MAP_FILE="${BUILD_DIR}/ec.map"
+
+if [ ! -d "${BUILD_DIR}" ]; then
+    exit 0
+fi
+
+if [ ! -f "${MAP_FILE}" ]; then
+    exit 0
+fi
+
+SEG_EXPECTED="00000000"
+SEG_START=$(grep 's_HOME' "${MAP_FILE}" | awk '{ print $2 }')
+
+if [ "${SEG_START}" != "${SEG_EXPECTED}" ]; then
+    printf "\x1B[31mHOME segment starts at %s; image will not boot\x1B[0m\n" "${SEG_START}"
+    exit 1
+fi