ld - How to build a C program using a custom version of glibc and static linking?

Question

I have built glibc 2.14 and installed it in directory ~/GLIBC/glibc_install. Now I want to build and run programs using this C library instead of my system's default C library.

• To be sure that I was using my custom glibc, I added a call to puts into glibc/stdio-common/printf.c:__printf to print a message.

• Then I rebuilt and reinstalled glibc.

• Then I wrote a "Hello, World" program and tried to compile and link it as follows:

  gcc -nodefaultlibs -static -lgcc -L~/GLIBC/glibc_install/lib -o myprog myprog.c
  

But I get the following linker error report:

/usr/lib/gcc/x86_64-linux-gnu/4.4.3/../../../../lib/crt1.o: In function `_start':
(.text+0x19): undefined reference to `__libc_csu_init'
/usr/lib/gcc/x86_64-linux-gnu/4.4.3/../../../../lib/crt1.o: In function `_start':
(.text+0x25): undefined reference to `__libc_start_main'
/tmp/ccACTQEp.o: In function `main':
c1.c:(.text+0xa): undefined reference to `puts'
collect2: ld returned 1 exit status

What am I doing wrong?

Answer 1

Following a couple of suggestions from the glibc help mailing list ([email protected]), I have a solution. It turns out that this task is a bit tricky because you have to tell the linker to omit everything it would normally include automatically (and silently), and then include back everything that it needs, including a bunch of start and end files. Some of the start and end files come from libc and some come from gcc, so the make rule is a bit complicated. Below is a general sample makefile to illustrate the approach. I will assume that you are building a program called prog from a source file called prog.c and that you have installed your custom glibc in directory /home/my_acct/glibc_install.

TARGET = prog
OBJ = $(TARGET).o
SRC = $(TARGET).c
CC = gcc
CFLAGS = -g
LDFLAGS = -nostdlib -nostartfiles -static
GLIBCDIR = /home/my_acct/glibc_install/lib
STARTFILES = $(GLIBCDIR)/crt1.o $(GLIBCDIR)/crti.o `gcc --print-file-name=crtbegin.o`
ENDFILES = `gcc --print-file-name=crtend.o` $(GLIBCDIR)/crtn.o
LIBGROUP = -Wl,--start-group $(GLIBCDIR)/libc.a -lgcc -lgcc_eh -Wl,--end-group

$(TARGET): $(OBJ)
        $(CC) $(LDFLAGS) -o $@ $(STARTFILES) $^ $(LIBGROUP) $(ENDFILES) 

$(OBJ): $(SRC)
        $(CC) $(CFLAGS) -c $^

clean:
        rm -f *.o *.~ $(TARGET)