adding bssdata example to explain what I mean about not using .data or zeroing .bss

and what happens to you if you assume something when using my code as a baseline.

bssdata/Makefile

@@ -0,0 +1,39 @@
+
+ARMGNU ?= arm-none-eabi
+
+COPS = -Wall -O2 -nostdlib -nostartfiles -ffreestanding 
+
+gcc : bssdata.hex bssdata.bin fun.list
+
+clean :
+	rm -f *.o
+	rm -f *.bin
+	rm -f *.hex
+	rm -f *.elf
+	rm -f *.list
+	rm -f *.img
+	rm -f *.bc
+
+vectors.o : vectors.s
+	$(ARMGNU)-as vectors.s -o vectors.o
+
+bssdata.o : bssdata.c
+	$(ARMGNU)-gcc $(COPS) -c bssdata.c -o bssdata.o
+
+bssdata.elf : memmap vectors.o bssdata.o 
+	$(ARMGNU)-ld vectors.o bssdata.o -T memmap -o bssdata.elf
+	$(ARMGNU)-objdump -D bssdata.elf > bssdata.list
+
+bssdata.bin : bssdata.elf
+	$(ARMGNU)-objcopy bssdata.elf -O binary bssdata.bin
+
+bssdata.hex : bssdata.elf
+	$(ARMGNU)-objcopy bssdata.elf -O ihex bssdata.hex
+
+
+fun.list : start.s simple fun.c
+	$(ARMGNU)-as start.s -o start.o
+	$(ARMGNU)-gcc $(COPS) -c fun.c -o fun.o
+	$(ARMGNU)-ld -T simple start.o fun.o -o fun.elf
+	$(ARMGNU)-objdump -D fun.elf > fun.list
+