Makefile, how to link 32bits library and 64bits library at the same time

Question

I have two libraries, one is called liblits.so, which is 32bits, another one is called liblinx.a, which is 64bits. I need to link both of them, in my Makefile, after adding CFLAGS += "-m32", I got error:

skipping incompatible liblinx.a when searching for -llinx

but there was no error for liblits.so. If I remove CFLAGS += "-m32"(my machine is 64bits), I got error:

skipping incompatible liblits.so when searching for -llits

but there was no error for liblinx.a. How can I link the 32bits library and 64bits library at the same time? Or do I have to have two consistent libraries?

My Makefile:

CFLAGS = -I.
CFLAGS += "-m32" 
LDFLAGS = -Llinx -llinx -Llib -llits -lrt -lpthread -Wl,-R,'lib' 
server:server.c
    gcc -o server $(CFLAGS) $(LDFLAGS) server.c

As far as I am aware, you cannot link 64-bit code with 32-bit code. You can, however, compile 32-bit x86 code on x86_64, and build an all-32-bit program that way. 32-bit x86 programs will *run* on x86_64 hardware. — John Bollinger, Feb 27 '15 at 15:06
possible duplicate of [Can 32 bit and 64 bit work together?](http://stackoverflow.com/questions/15971830/can-32-bit-and-64-bit-work-together) — Piotr Siupa, Feb 27 '15 at 15:07

score 3 · Accepted Answer · answered Feb 27 '15 at 15:06

You need consistent libraries. The machine code in the 32- and 64-bit libraries is incompatible -- you have different pointer sizes, for example, leading to a different expectation of the size of the virtual address space and similar problems.

How would you make an object outside the 4GB a 32-bit pointer can address but that a function in the 64-bit library can create known to a function in the 32-bit library? It's impossible, and for reasons like these and many others, so is linking 32- and 64-bit libraries to the same binary.

Makefile, how to link 32bits library and 64bits library at the same time

1 Answers1