From 19cd3b0f71d93dc3e97a9ab9ea763b9d3d1727fa Mon Sep 17 00:00:00 2001
From: Eric Wild <ewild@sysmocom.de>
Date: Fri, 3 Apr 2020 21:33:30 +0200
Subject: [PATCH] firmware: do not allow undefined symbols

For some reason undefined symbols were downgraded to warnings, which
means building a firmware that calls missing functions  (= address zero)
was perfectly fine, which of course made development more exciting....

This applies to builtins, too, printf of one char gets downgraded to
putchar, which we don't have, so disable builtins.

Change-Id: I492f41ad4162b9d07b1881ae4aed019db2dff8b5
---
 firmware/Makefile                                | 4 ++--
 firmware/libboard/common/source/board_lowlevel.c | 5 +++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/firmware/Makefile b/firmware/Makefile
index ccf58438..cc406738 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -164,14 +164,14 @@ CFLAGS += -Wno-suggest-attribute=noreturn
 # -mlong-calls  -Wall
 #CFLAGS += -save-temps -fverbose-asm
 #CFLAGS += -Wa,-a,-ad
-CFLAGS += -D__ARM
+CFLAGS += -D__ARM -fno-builtin
 CFLAGS += --param max-inline-insns-single=500 -mcpu=cortex-m3 -mthumb # -mfix-cortex-m3-ldrd
 CFLAGS += -ffunction-sections -g $(OPTIMIZATION) $(INCLUDES) -D$(CHIP) -DTRACE_LEVEL=$(TRACE_LEVEL) -DALLOW_PEER_ERASE=$(ALLOW_PEER_ERASE)
 CFLAGS += -DGIT_VERSION=\"$(GIT_VERSION)\"
 CFLAGS += -DBOARD=\"$(BOARD)\" -DBOARD_$(BOARD)
 CFLAGS += -DAPPLICATION=\"$(APP)\" -DAPPLICATION_$(APP)
 ASFLAGS = -mcpu=cortex-m3 -mthumb -Wall -g $(OPTIMIZATION) $(INCLUDES) -D$(CHIP) -D__ASSEMBLY__
-LDFLAGS = -mcpu=cortex-m3 -mthumb -Wl,--cref -Wl,--check-sections -Wl,--gc-sections -Wl,--entry=ResetException -Wl,--unresolved-symbols=report-all -Wl,--warn-common -Wl,--warn-section-align -Wl,--warn-unresolved-symbols -Wl,--print-memory-usage $(LIB)
+LDFLAGS = -mcpu=cortex-m3 -mthumb -Wl,--cref -Wl,--check-sections -Wl,--gc-sections -Wl,--entry=ResetException -Wl,--unresolved-symbols=report-all -Wl,--warn-common -Wl,--warn-section-align -Wl,--print-memory-usage -Wl,--no-undefined $(LIB)
 #LD_OPTIONAL=-Wl,--print-gc-sections -Wl,--stats
 
 # Append BIN directories to output filename
diff --git a/firmware/libboard/common/source/board_lowlevel.c b/firmware/libboard/common/source/board_lowlevel.c
index b4d7d32c..1ddbcba2 100644
--- a/firmware/libboard/common/source/board_lowlevel.c
+++ b/firmware/libboard/common/source/board_lowlevel.c
@@ -218,3 +218,8 @@ void mdelay(unsigned int msecs)
 	do {
 	} while ((jiffies - jiffies_start) < msecs);
 }
+
+void abort() {
+	NVIC_SystemReset();
+	while(1) {};
+}