ld: not warning undefined symbols

Altera_Forum · ‎11-06-2006

Hi!

I have a program which I have been linking against various libraries, and I have found that when there's a missing object, it doesn't say anything. Instead, when it tries to execute that object, it hangs.

Is that a usual thing? I suppose that there's an option to tell the linker to warn about undefined symbols, so... anyone could point me to it?

I've tried with "--no-undefined", bout it doesn't say anything new...

Thank you

aLeX

Altera_Forum · ‎11-07-2006

Did you add "-elf2flt" for linking to uClinux?

The elf2flt should fail on undefined symbols.

Or you can check the link map file before elf2flt.

Altera_Forum · ‎11-07-2006

I'm not using "elf2flt", because I'm using the example I found in the documentation... In the Makefile, I wrote:

TSTPRG = myprog.exe
all: $(TSTPROG)

When I do "make all", it compiles my program and generates an .exe file. I've seen that it uses elf2flt

nios2-linux-uclibc-gcc -nostdinc -O2 -I/home/indes/opo/kernel/uClinux-dist-test/uClibc/include -I/opt/nios2/lib/gcc/nios2-linux-uclibc/3.4.6/include -fno-optimize-sibling-calls -mhw-mul -mhw-mulx -Wall -c -o myprog.o myprog.c
nios2-linux-uclibc-gcc -msys-crt0=/home/uClibc/lib/crt0.o -r -d -L/home/uClinux-dist-test/uClibc/lib -o myprog.bin myprog.o /opt/nios2/lib/gcc/nios2-linux-uclibc/3.4.6/../../../../nios2-linux-uclibc/lib/libm.a /opt/nios2/lib/gcc/nios2-linux-uclibc/3.4.6/libgcc.a /home/indes/opo/kernel/uClinux-dist-test/uClibc/lib/libc.a --no-undefined
nios2-linux-uclibc-ld -T /opt/nios2/scripts/elf2flt.ld -Ur -o myprog.elf myprog.bin
/opt/nios2/bin/elf2flt  -o myprog.flt myprog.elf
cp -f myprog.flt myprog.exe
rm myprog.elf myprog.flt myprog.bin myprog.o

The strange thing is that it shows the same if I include the references to the libraries it needs, or if I don't include them. It doesn't warn about anything...

any idea?

aLeX

Altera_Forum · ‎11-07-2006

Though the same flow may work on arm linux.

It does not work for nios2 linux.

You'd better follow the wiki, it is easy.

http://nioswiki.jot.com/wikihome/operating...ms/compilehello (http://nioswiki.jot.com/wikihome/operatingsystems/compilehello)

In case there are any undefined symbols, it will fail.

Altera_Forum · ‎11-07-2006

What the wiki says is more or less similar to whaat I've been doing. Maybe I have not been clear, but I'm able to compile the program correctly, and it executes. The problem is that I've had to track the library dependencies, because the compiler didn't warned me about them. the wiki didn't say anything about it.

The problem now is that I have to compile other programs with mucho more dependencies than the last one, and I don't want to include ALL my libraries in each program...

aLeX

Altera_Forum · ‎11-08-2006

Please check man pages of "ld" .

1. map file, you can get map file after linkage, you can find if any undefined symbols.

2. you can ask "ld", ie "nios2-linux-uclibc-ld", to run multiple pass scanning.

You can find more gnu tools guides from doc on www.gnu.org .

The nios2-linux-uclibc-gcc will use uClibc by default.

If you just want to compile uClinux apps, there is no need to use -msys-crt0, -nostdinc and -nostdlib ,etc.

Altera_Forum · ‎11-08-2006

I have read the man pages of "ld". I am running multiple pass ld, but the problem was to find waht libraries were needed, without having to link against all the libraries I have (I have many libraries and programs, some programs link with some libraries, and some with others).

The man pages of ld refer to standard ld, and it seems that nios2-linux-ld doesn't have ALL the options (doesn't recognize the option -M for mapping the output)

Anyway, I'll try to link against ALL the libraries, even if the compile time gets increased a lot.

The "-msys-crt0, -nostdinc and -nostdlib ,etc.", ... I used the Makefile that the Altera IDE generated at the beginning, before compiling in linux.

Thank you...

aLeX

Altera_Forum · ‎11-09-2006

--- Quote Start ---

originally posted by abg@Nov 8 2006, 11:36 PM

i have read the man pages of "ld". i am running multiple pass ld, but the problem was to find waht libraries were needed, without having to link against all the libraries i have (i have many libraries and programs, some programs link with some libraries, and some with others).

the man pages of ld refer to standard ld, and it seems that nios2-linux-ld doesn't have all the options (doesn't recognize the option -m for mapping the output)

anyway, i'll try to link against all the libraries, even if the compile time gets increased a lot.

the "-msys-crt0, -nostdinc and -nostdlib ,etc.", ... i used the makefile that the altera ide generated at the beginning, before compiling in linux.

thank you...

alex

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--- quote end ---

--- Quote End ---

You still should not use those "-msys-crt0, -nostdinc and -nostdlib " flags.

You need them with altera's nios2-elf compiler.

But DON'T use them with nios2-linux-uclibc compiler for uClinux.

To pass flag to ld from gcc, you need -Wl,

nios2-linux-uclibc-gcc -Wl,"-Map hello.map" -elf2flt hello.c -o hello

You can have different target rule for each program and libs options in your Makefile.

eg, make model1, or make model2 etc.