Interleave Assembly and Source for avr-objdump

Question

Trying to get avr-objdump to generate a listing that interleaves the assembly with the source code. I've tried a bunch of debugging arguments in different configurations but I can't seem to get it. The best I could do was getting it to interleave the object with line numbers from the assembly (avr-objdump -lS spi.o)

Original Makefile

Here's my current Makefile:

PREFIX=avr-
CC=${PREFIX}gcc
OBJCOPY=${PREFIX}objcopy

BIN=knightrider
MCU=attiny85
OBJS=../src/tinySPI.o src/knightrider.o

PROG?=atmelice_isp
PORT?=usb

CFLAGS=-g -mmcu=${MCU} -ffunction-sections -fdata-sections
LDFLAGS=-mmcu=${MCU} -Wl,--gc-sections

${BIN}.hex: ${BIN}.elf
    @mkdir -p bin
    ${OBJCOPY} -O ihex -R .eeprom build/$< bin/$@

${BIN}.elf: ${OBJS}
    @mkdir -p build
    ${CC} ${LDFLAGS} -o build/$@ $?

install: ${BIN}.hex
    avrdude -c ${PROG} -P ${PORT} -p ${MCU} -U flash:w:${BIN}.hex:i -qq

clean:
    rm -f build/*
    rm -f bin/*

fuses:
    avrdude -c ${PROG} -P ${PORT} -p ${MCU} -U lfuse:w:0x62:m -U hfuse:w:0xDF:m -U efuse:w:0xFF:i -qq

What would I need to change in order to run avr-objdump and get an interleaved listing of an .o and its corresponding .c (e.g. spi.o and spi.c)?

Answer 1

First make sure you add -g to all your compilation commands.

Then you can run avr-objdump -S build/spi.elf (for instance).

Also I see you're missing the MCU definition in your link command. Without that it won't link in the proper C startup routines and your program will most probably not run.

Here is a makefile I use:

PREFIX=avr-
CC=${PREFIX}gcc
CXX=${PREFIX}g++
LD=${PREFIX}ld
AS=${PREFIX}as
OBJCOPY=${PREFIX}objcopy
OBJDUMP=${PREFIX}objdump

BIN=blink
MCU=atmega328p
OBJS=blink.o

CFLAGS=-g -mmcu=${MCU} -ffunction-sections -fdata-sections
CXXFLAGS=-g -mmcu=${MCU} -ffunction-sections -fdata-sections -fno-exceptions
LDFLAGS=-mmcu=${MCU} -Wl,--gc-sections

${BIN}.hex: ${BIN}.elf
    ${OBJCOPY} -O ihex -R .eeprom $< $@

${BIN}.elf: ${OBJS}
    ${CC} ${LDFLAGS} -o $@ $? 
    ${OBJDUMP} -S $@ > ${BIN}.dis

install: ${BIN}.hex
    avrdude -C ./avrdude.conf -c usbasp -p ${MCU} -U flash:w:${BIN}.hex
 -qq

clean:
    rm -f *.o *.elf *.hex

fuses:
    avrdude  -c usbasp -p ${MCU} -C avrdude.conf -U lfuse:w:0xff:m -U h
fuse:w:0xd6:m -U efuse:w:0x05:m -qq