GNU Arm Embedded Toolchain

Different behavior when linking with gcc and ld: Unable to link __aeabi_uldivmod when link with arm-none-eabi-ld

Asked by Thong Dam

When I tried to link source code with:
arm-none-eabi-ld -T linker.ld $(OBJECT_FILES) -L $(LIB_PATH) -lm -lc

There is error that "undefined reference to `__aeabi_uldivmod ' ". This project will build successfully when I tried to remove the instruction which required this API.

I also be able to link the same object file with arm-none-eabi-gcc:
arm-none-eabi-gcc -nostartfiles -T$(LINKER_FILE) -Os -g -Wall -mcpu=cortex-r7 -mthumb -mfpu=vfpv4 -mfloat-abi=hard -L $(LIB_DIRS) -lm -lc
It event work without needed for -L and -l (however I need them for additional math library).

So my question are:
1. What is the different between these 2 approaches? Why it did not work with LD version?
2. Is there any drawback when I link project use GCC command?

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Ramana Radhakrishnan (ramana) said : 		#1

Try adding a -lgcc to your link flags. - this is because there's no instruction to do a divmod and your program had a call out to a libgcc helper function. Since you aren't using the compiler driver and the linker directly the link error shows up.

Ramana

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From: <email address hidden> <email address hidden> on behalf of Thong Dam <email address hidden>
Sent: 07 October 2020 04:40
To: gnu-rm-support
Subject: [Gnu-rm-support] [Question #693328]: Different behavior when linking with gcc and ld: Unable to link __aeabi_uldivmod when link with arm-none-eabi-ld

New question #693328 on GNU Arm Embedded Toolchain:
https://answers.launchpad.net/gcc-arm-embedded/+question/693328

When I tried to link source code with:
arm-none-eabi-ld -T linker.ld $(OBJECT_FILES) -L $(LIB_PATH) -lm -lc

There is error that "undefined reference to `__aeabi_uldivmod ' ". This project will build successfully when I tried to remove the instruction which required this API.

I also be able to link the same object file with arm-none-eabi-gcc:
arm-none-eabi-gcc -nostartfiles -T$(LINKER_FILE) -Os -g -Wall -mcpu=cortex-r7 -mthumb -mfpu=vfpv4 -mfloat-abi=hard -L $(LIB_DIRS) -lm -lc
It event work without needed for -L and -l (however I need them for additional math library).

So my question are:
1. What is the different between these 2 approaches? Why it did not work with LD version?
2. Is there any drawback when I link project use GCC command?

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