CODEWITHSUNDEEP
ccross-compilingld
Phil123456
Phil123456

Reputation: 83

ARM - C - arm-none-eabi-ld : not finding vsprintf,strcpy

On Ubuntu I cross-compile a code for the raspberry pi

but when I try to link objects that use standard c libraries I just added

arm-none-eabi-ld -g vectors.o notmain.o bm_bcm2835.o uart.o -T memmap -o notmain.elf

it complains about not finding standard functions

uart.c:135: undefined reference to `strcpy'
uart.c:142: undefined reference to `vsprintf'

so far I tried, adding -lc -lgcc but the linker complains it cannot find them either

arm-none-eabi-ld: cannot find -lc
arm-none-eabi-ld: cannot find -lgcc

I tried adding these flags to the compiler, it compiles fine, but the linker throws the same error

any idea what's going wrong ?

here is the makefile:

ARMGNU ?= arm-none-eabi

AOPS = --warn --fatal-warnings
COPS = -Wall -Werror -O2 -nostdlib -nostartfiles -ffreestanding -g
LDOPS = -g

all : kernel.img

clean :
rm -f *.o
rm -f *.bin
rm -f *.hex
rm -f *.srec
rm -f *.elf
rm -f *.list
rm -f *.img

vectors.o : vectors.s
$(ARMGNU)-as $(AOPS) vectors.s -o vectors.o

uart.o : uart.c
$(ARMGNU)-gcc $(COPS) -c uart.c -o uart.o -lc -lgcc

notmain.o : notmain.c
$(ARMGNU)-gcc $(COPS) -c notmain.c -o notmain.o

notmain.elf : memmap vectors.o notmain.o uart.o
$(ARMGNU)-ld $(LDOPS) vectors.o notmain.o uart.o -T memmap -o notmain.elf
$(ARMGNU)-objdump -D notmain.elf > notmain.list

kernel.img : notmain.elf
$(ARMGNU)-objcopy --srec-forceS3 notmain.elf -O srec notmain.srec
$(ARMGNU)-objcopy notmain.elf -O binary kernel.img

thanks for helping me on this

Upvotes: 2

Views: 880

Answers (2)

Phil123456
Phil123456

Reputation: 83

since it's bare metal, there is no sub structure for standards c functions

so here is an example of how to implement bare metal subsystem (heap and such) with newlib

https://www.raspberrypi.org/forums/viewtopic.php?f=72&t=280209&p=1697302#p1697302

Upvotes: 1

Florian Weimer
Florian Weimer

Reputation: 33717

If you build with -nostdlib -nostartfiles -ffreestanding, you are telling the compiler (driver) that you do not want to build for a standard C environment. As a result, standard C functions such as vfprintf and strcpy are not available and cannot be used.

Upvotes: 1

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