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AVR linker error, “relocation truncated to fit”

由 我只是一个虾纸丫 提交于 2019-11-29 10:19:27

Explanation:

As the error message suggests, the issue has to do with the relocation (of code) which causes some truncation to occur. The message comes from the linker which is trying to map pieces of code to appropriate locations in the program memory.

When code is placed or moved to some location ("relocation") and this code is referred to from another piece of code, via JMP or CALL (i.e. a function call), the relocated address has to be added to the JMP or CALL instruction referring to it.

The AVR devices support two kinds of jump/call instructions: JMP vs. RJMP, and CALL vs. RCALL. The R variants make calls relative to the current location and are more efficient both in usage of program memory and execution time. This comes at a cost though: RJMP and RCALL can only be used for addresses in the range of +/-4kb from their location in program memory. This is never a problem on devices with no more than 8kb of program memory because the whole 8kb range can be addressed from any location via RCALL or RJMP.

On devices with more than 8kb of program memory, however, this is not true for all possible locations. Therefore, if the linker decides it can put the code to be called within the +/-4kb range from the RJMP/RCALL there will be no problem, but if the linker fails to (re-)locate the code to be within that range, RJMP/RCALL cannot be used to reach the code's new address, the address is thus truncated (just like when doing uint16_t value = 12345; uint8_t truncatedValue = value; in C) and the generated code breaks.

Note that this may or may not happen for any given project exceeding 4kb of program memory (on devices with >8kb of program memory) at some point, because it depends on the relocation of code needed, which may basically change with every new line of C code added or removed, with every library added to be linked in, or even the order in which the libraries or other pieces of code are linked in (e.g. calling from "A" to "B" may work when the linker locates the code like "A B C" but fail when the linker decides to relocate like "A C B").

Solution:

You have to let the compiler know that it needs to generate JMP/CALL instructions instead of the (more efficient) RJMP/RCALL instructions. In AVR Studio/Atmel Studio this can be done in the project's properties, toolchain, AVR/GNU C compiler, optimization. The relevant option is "Use rjmp/rcall (limited range) on >8k devices (-mshort-calls)" which needs to be unchecked to prevent the named error.
As the label indicates, the relevant command line option is -mshort-calls which needs to be removed from the gcc command line parameter list to achieve the same when invoking gcc from outside of the IDE.

Update:

To avoid the unnecessary confusion this error may cause -mshort-calls was deprecated in avr-gcc 4.7 and will be removed from 4.8. Source: GCC 4.8 Changes.

Users should now use -mrelax instead to generate binaries that have the call optimizations where possible but will never produce the error.

I ran into the avr-gcc relocation truncation error message and spent a couple of days sorting it out. In short, there appears to be a bug in the linker.

For a quick fix, put this in your code in the global variable area. You may have to try a few different array sizes.

#include <avr/pgmspace.h>
const char pad[500] PROGMEM = { 0 };

Here's what's going on. The first 224 bytes of flash memory are the interrupt vector table. When an interrupt occurs (like a timer expires or there's a byte waiting in some receive buffer), this table tells the processor what code to execute. This example doesn't use many interrupts, so unused vectors get sent to the routine bad_interrupt(). Here's a few lines from the vector table.

0000 <__vectors>:
   0:    0c 94 08 08   jmp   0x1010  ; 0x1010 <__ctors_end>
   4:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
   8:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
   c:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
  10:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
  14:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
  18:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
  1c:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
  20:    0c 94 12 08   jmp   0x1024  ; 0x1024 <__bad_interrupt>
  24:    ff c7         rjmp  .+4094  ; 0x1024 <__bad_interrupt>
  26:    00 00         nop
  28:    fd c7         rjmp  .+4090  ; 0x1024 <__bad_interrupt>
  2a:    00 00         nop
  2c:    fb c7         rjmp  .+4086  ; 0x1024 <__bad_interrupt>
  2e:    00 00         nop
  30:    f9 c7         rjmp  .+4082  ; 0x1024 <__bad_interrupt>

A few things to notice

  • The bad_interrupt routine is located at address 0x1024
  • The first few vectors use a direct jump to 0x1024
  • The last vectors use a relative jump to 0x1024

The use of both jmp and rjmp is an artifact of the -mrelax compiler flag. Amongst other things, it tells the compiler to use rjmp instructions when the destination is close enough (which is +/- 4k). Otherwise, the compiler should use jmp. This isn't a bad thing, rjmp instructions run 1 clock faster and use 2 bytes less data.

Without -mrelax, the compiler uses only jmp instructions in the vector table and the problem goes away. BTW, for our purposes, --relax is the same as -mrelax.

The problem is that the linker is getting jammed up somehow. In the above example, when the bad_interrupt routine is located at address 0x1028, the vector should at address 0x24 should turn into a jmp but the linker can't do it for some reason. Instead, it leaves the instruction as a rjmp with a relative offset of +4098. As the allowed range is 4096, the offset would get truncated to +2, which is a serious error.

The reason why "pad[500] PROGMEM = { 0 };" should work is it will allocate a chunk of flash memory between the vector table and moves bad_interrupt() far enough away from the vector table that the linker isn't even tempted to use a rjmp instruction.

In searching the web, this appears to be a chronic problem with all sorts of solutions that sometimes work. Popular are using more/less PSTR("Hello World") constructs and various -lm -lc options. I suspect these things are just jiggling around subroutine addresses and by blind luck they fall in places that work.

Below is the code I used to isolate this bug.

//
// rjmp vector table relocation truncation bug
//
// works when the -mrelax option is not used
//
//  avr-gcc -g -Wall -mrelax pad.c -mmcu=atmega2560 -Wl,-Map -o pad.elf
//  avr-objdump -h -S pad.elf > pad.list
//
//  avr-gcc --version -> avr-gcc (GCC) 4.7.2
//

#include <avr/pgmspace.h>

// note, there are other bands of works/fails
//
// 3884 works
// 3886 fails
// 3894 fails
// 3896 works
const char pad[3886] PROGMEM = { 0 };

int main() {

  int   i, j;

  for (i = 0; 1; i++)
    j += pad[i];
}

I've solved the problem, i've restructured code (I've deleted almost all globals variables) and i've added '-lc -lm -lc' flags to makefile. I suppose the problem was the code structure, too many global variables due to bad adaptation from an arduino code style (All source files are pasted into in the same file) I put the makefile here, I hope it is useful to someone:

TARGET = IMU
PORT = /dev/ttyUSB0
BAUD_P = 57600
BAUD_T = 9600
PROGRAMMER = arduino
MCU = atmega328p
F_CPU = 8000000L

CXX_SRCS = ADXL345.cpp \
       ApplicationRoutines.cpp \
       DCM.cpp \
       HMC5883L.cpp \
       ITG3200.cpp \
       output.cpp \
       timing.cpp \
       vector.cpp

CXX_OBJ = $(CXX_SRCS:.cpp=.o)

CXX_HDRS = ADXL345.h \
       ApplicationRoutines.h \
       DCM.h \
       declarations.h \
       HMC5883L.h \
       ITG3200.h \
       output.h \
       timing.h \
       vector.h

CORE_DIR = libarduinocore

CORE_CXX_SRCS = $(CORE_DIR)/HardwareSerial.cpp \
        $(CORE_DIR)/Print.cpp \
        $(CORE_DIR)/Tone.cpp \
        $(CORE_DIR)/WMath.cpp \
        $(CORE_DIR)/WString.cpp

CORE_CXX_OBJ = $(CORE_CXX_SRCS:.cpp=.o)

CORE_CC_SRCS = $(CORE_DIR)/pins_arduino.c \
           $(CORE_DIR)/WInterrupts.c \
           $(CORE_DIR)/wiring_analog.c \
           $(CORE_DIR)/wiring.c \
           $(CORE_DIR)/wiring_digital.c \
           $(CORE_DIR)/wiring_pulse.c \
           $(CORE_DIR)/wiring_shift.c

CORE_CC_OBJ = $(CORE_CC_SRCS:.c=.o)

CORE_HDRS = $(CORE_DIR)/binary.h \
        $(CORE_DIR)/HardwareSerial.h \
        $(CORE_DIR)/pins_arduino.h \
        $(CORE_DIR)/Print.h \
        $(CORE_DIR)/Stream.h \
        $(CORE_DIR)/WCharacter.h \
        $(CORE_DIR)/WConstants.h \
        $(CORE_DIR)/wiring.h \
        $(CORE_DIR)/wiring_private.h \
        $(CORE_DIR)/WProgram.h \
        $(CORE_DIR)/WString.h

ARD_LIB_DIR = libraries

ARD_LIB_CXX_SRCS = $(ARD_LIB_DIR)/EEPROM/EEPROM.cpp \
           $(ARD_LIB_DIR)/Wire/Wire.cpp \
           $(ARD_LIB_DIR)/HMC58X3/HMC58X3.cpp
ARD_LIB_CC_SRCS = $(ARD_LIB_DIR)/Wire/utility/twi.c

ARD_LIB_CXX_OBJ = $(ARD_LIB_CXX_SRCS:.cpp=.o)
ARD_LIB_CC_OBJ = $(ARD_LIB_CC_SRCS:.c=.o)

CC = avr-gcc
CXX = avr-g++
OBJCOPY = avr-objcopy
OBJDUMP = avr-objdump
AR  = avr-ar
SIZE = avr-size
NM = avr-nm
AVRDUDE = avrdude

ARD_LIB_INC = -I$(ARD_LIB_DIR) -I$(ARD_LIB_DIR)/EEPROM -I$(ARD_LIB_DIR)/Wire -I$(ARD_LIB_DIR)/HMC58X3 -I$(ARD_LIB_DIR)/Wire/utility

#FLAGS_WARN = -Wall -Wstrict-prototypes
#FLAGS_TUNING = -ffunction-sections -fdata-sections -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums
FLAGS_OPT = -Os

ALL_INC = -I. $(ARD_LIB_INC) -I$(CORE_DIR)
OBJS = $(CXX_OBJ) $(CORE_CXX_OBJ) $(CORE_CC_OBJ) $(ARD_LIB_CC_OBJ) $(ARD_LIB_CXX_OBJ)
ALL_OBJS := $(addprefix build/, $(notdir $(OBJS)))
ALL_CFLAGS = -mmcu=$(MCU) -DF_CPU=$(F_CPU) $(ALL_INC) $(FLAGS_WARN) $(FLAGS_TUNNIG) $(FLAGS_OPT)
ALL_CXXFLAGS = -mmcu=$(MCU) -DF_CPU=$(F_CPU) $(ALL_INC) $(FLAGS_TUNNIG) $(FLAGS_OPT) #-Wall
#ALL_ASFLAGS = -mmcu=$(MCU) -I. -x assembler-with-cpp $(ASFLAGS)
END_FLAGS = -lc -lm -lc

all : $(TARGET).hex

$(TARGET).hex : $(TARGET).out
    avr-objcopy -O ihex -R .eeprom $(TARGET).out $(TARGET).hex

$(TARGET).out : $(OBJS)
    $(CXX) $(ALL_CXXFLAGS) main.cpp $(ALL_OBJS) -o $(TARGET).out $(END_FLAGS)

upload : $(TARGET).hex
    avrdude -c$(PROGRAMMER) -p$(MCU) -b$(BAUD_P) -P$(PORT) -U flash:w:$(TARGET).hex

serialmon :
    picocom -b$(BAUD_T) $(PORT)

.SUFFIXES: .elf .hex .eep .lss .sym .cpp .o .c .s .S

# Define all listing files.
#LST = $(ASRC:.S=.lst) $(CXXSRC:.cpp=.lst) $(SRC:.c=.lst)

# Compile: create object files from C++ source files.
.cpp.o:
    $(CXX) -c $(ALL_CXXFLAGS) $< -o $(addprefix build/, $(notdir $@)) $(END_FLAGS)

# Compile: create object files from C source files.
.c.o:
    $(CC) -c $(ALL_CFLAGS) $< -o $(addprefix build/, $(notdir $@)) $(END_FLAGS)


# Compile: create assembler files from C source files.
#.c.s:
#   $(CC) -S $(ALL_CFLAGS) $< -o build/$@ -lm


# Assemble: create object files from assembler source files.
#.S.o:
#   $(CC) -c $(ALL_ASFLAGS) $< -o build/$@

I've been working on this problem for the past few hours, and finally solved it. For me it had to do with the fact that the avr libm.a must be included in the linker command, and I was using the Math.h library, which is separate from the libc.a library, and wasn't being linked correctly.

Try modifying the linker command to look like this by adding -lc -lm at the beginning of the command and -lc at the end:

${CMD}  -lc -lm ${FLAGS} ${OUTPUT_FLAG}${OUTPUT_PREFIX}${OUTPUT}  ${INPUTS}  -lc

My reference: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1290294587

I got rid of relocation errors after a long struggle by adding -lm -lc to SET(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "-lm -lc") so they will be appended at the end by CMke in link.txt My CMakeLists.txt

# generated by cmkoder 
PROJECT (ermote1.cmk)
CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
SET(CMAKE_SYSTEM_NAME Generic)
SET(OUT_BINARY_FILE ermote1)

SET(ENV{CROSS_COMPILE} avr-)
SET(ENV{ARCH} arm)
SET(ENV{TC_BASE} /home/arduino-1.0.5)
SET(CROSS_COMPILE avr-)
SET(ARCH arm)
SET(TC_BASE /home/arduino-1.0.5)
SET(TC_SRC_PATH ${TC_BASE}/libraries/)

SET(CMAKE_CXX_COMPILER ${CROSS_COMPILE}c++)
SET(CMAKE_C_COMPILER ${CROSS_COMPILE}gcc)
SET(TC_LIB_LINKER ${CROSS_COMPILE}ar)
SET(TC_GDB ${CROSS_COMPILE}gdb)
SET(HW_MMCU "-mmcu=atmega328p")
SET(HW_DF_CPU "-DF_CPU=16000000L")
SET(HW_VARIANT "eightanaloginputs")
SET (TC_DEFINES "-DARDUINO=105 -DUSB_VID=null  -DUSB_PID=null")
SET(CMAKE_CXX_FLAGS "-g -Os -Wall -fno-exceptions -ffunction-sections  -fdata-sections -lm -Wl,-gc-sections ${HW_MMCU} ${HW_DF_CPU} -lc  ${TC_DEFINES}")

SET(CMAKE_C_FLAGS  "${CMAKE_CXX_FLAGS}")

SET(CMAKE_SHARED_LIBRARY_LINK_CXX_FLAGS "-lm -lc")

SET(CMAKE_FIND_ROOT_PATH  ${TC_BASE}/hardware/tools/avr/bin ${TC_BASE}/hardware/tools ${TC_BASE}/hardware/tools/avr/lib/avr/lib)

SET(CMAKE_LIBRARY_PATH  "")

INCLUDE_DIRECTORIES (${TC_BASE}/hardware/arduino/cores/arduino/ 
                     ${TC_BASE}/hardware/arduino/variants/${HW_VARIANT}/ 
                     ${TC_BASE}/libs/ 
                     ${TC_BASE}/libraries/ 
                     ${TC_SRC_PATH}SoftwareSerial 
                     ${TC_SRC_PATH}Wire 
                     ${TC_SRC_PATH}Wire/utility 
                     ${TC_SRC_PATH}Ermote 
                     ${TC_SRC_PATH}Adafruit_BMP085)

SET(TC_SOURCES ${TC_BASE}/hardware/arduino/cores/arduino/HardwareSerial.cpp 
               ${TC_BASE}/hardware/arduino/cores/arduino/Print.cpp 
               ${TC_BASE}/hardware/arduino/cores/arduino/WInterrupts.c 
               ${TC_BASE}/hardware/arduino/cores/arduino/wiring_analog.c 
               ${TC_BASE}/hardware/arduino/cores/arduino/wiring.c 
               ${TC_BASE}/hardware/arduino/cores/arduino/wiring_digital.c 
               ${TC_BASE}/hardware/arduino/cores/arduino/wiring_pulse.c 
               ${TC_BASE}/hardware/arduino/cores/arduino/wiring_shift.c 
               ${TC_BASE}/hardware/arduino/cores/arduino/WMath.cpp 
               ${TC_BASE}/hardware/arduino/cores/arduino/WString.cpp 
               ${TC_BASE}/hardware/arduino/cores/arduino/main.cpp 
               ${TC_BASE}/hardware/arduino/cores/arduino/new.cpp)


SET(SDK_SRCS ${TC_SRC_PATH}/SoftwareSerial/SoftwareSerial.cpp 
             ${TC_SRC_PATH}/Wire/Wire.cpp 
             ${TC_SRC_PATH}/Wire/utility/twi.c 
             ${TC_SRC_PATH}/Adafruit_BMP085/Adafruit_BMP085.cpp)

SET(PRJ_SRCS start.cpp)


FIND_PROGRAM(AVROBJCOPY "avr-objcopy")
FIND_PROGRAM(AVRDUDE "avrdude")
FIND_PROGRAM(AVRSIZE "avr-size")

if(AVROBJCOPY)
    add_custom_target(hex)
    add_dependencies(hex ${OUT_BINARY_FILE})

    add_custom_command(TARGET hex POST_BUILD
        COMMAND ${AVROBJCOPY} -O ihex -R .eeprom  ./${OUT_BINARY_FILE} ./${OUT_BINARY_FILE}.hex
    )
    add_custom_target(elf)
    add_dependencies(elf ${OUT_BINARY_FILE})

    add_custom_command(TARGET elf POST_BUILD
        COMMAND ${AVROBJCOPY} -O ihex -R .eeprom  ./${OUT_BINARY_FILE} ./${OUT_BINARY_FILE}.elf
    )
    add_custom_target(eep)
    add_dependencies(eep ${OUT_BINARY_FILE})

    add_custom_command(TARGET eep POST_BUILD
        COMMAND ${AVROBJCOPY} -O ihex -j .eeprom --set-section-flags=.eeprom=alloc,load --no-change-warnings --change-section-lma .eeprom=0  ./${OUT_BINARY_FILE} ./${OUT_BINARY_FILE}.eep
    )

endif()

ADD_EXECUTABLE ( ${OUT_BINARY_FILE} ${TC_SOURCES} ${SDK_SRCS} ${PRJ_SRCS})

link.txt would look like.

avr-c++   -g -Os -Wall -fno-exceptions -ffunction-sections  -fdata- 
sections -lm -Wl,-gc-sections -mmcu=atmega328p -DF_CPU=16000000L -lc  
-DARDUINO=105 -DUSB_VID=null  -DUSB_PID=null    <all the 
CMakeFiles/....cpp.o >  -o ermote1 -lm -lc

I sorted it out by overring rules at bottom of my makefile :

# (...)
include /usr/share/arduino/Arduino.mk

LDFLAGS += -lc -lm

$(TARGET_ELF):  $(LOCAL_OBJS) $(CORE_LIB) $(OTHER_OBJS)
    $(CC) $(LDFLAGS) -o $@ $(LOCAL_OBJS) $(CORE_LIB) $(OTHER_OBJS)
标签
linker
arduino
linker-errors
avr
avr-gcc
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