Trying to compile a 32 bit asm program with the following commands.
as --32 select.s -o main.o
ld -m elf_i386 -I/lib/ld-linux.so.2 -lc main.o -o main
Outputs:
In function _start':
(.text+0x21): undefined reference to esp'
Using the following gcc command:
gcc -m32 -nostartfiles -o main select.s -v
Outputs:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.9.2-10' --with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.9 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.9 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --with-arch-32=i586 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.9.2 (Debian 4.9.2-10)
COLLECT_GCC_OPTIONS='-m32' '-nostartfiles' '-o' 'main' '-v' '-mtune=generic' '-march=i586'
as -v --32 -o /tmp/ccGkw2Rn.o select.s
GNU assembler version 2.25 (x86_64-linux-gnu) using BFD version (GNU Binutils for Debian) 2.25
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.9/:/usr/lib/gcc/x86_64-linux-gnu/4.9/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/4.9/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/4.9/32/:/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32/:/lib/../lib32/:/usr/lib/../lib32/:/usr/lib/gcc/x86_64-linux-gnu/4.9/:/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-m32' '-nostartfiles' '-o' 'main' '-v' '-mtune=generic' '-march=i586'
/usr/lib/gcc/x86_64-linux-gnu/4.9/collect2 -plugin /usr/lib/gcc/x86_64-linux-gnu/4.9/liblto_plugin.so -plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper -plugin-opt=-fresolution=/tmp/cc1n81fB.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s --sysroot=/ --build-id --eh-frame-hdr -m elf_i386 --hash-style=gnu -dynamic-linker /lib/ld-linux.so.2 -o main -L/usr/lib/gcc/x86_64-linux-gnu/4.9/32 -L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../../../lib32 -L/lib/../lib32 -L/usr/lib/../lib32 -L/usr/lib/gcc/x86_64-linux-gnu/4.9 -L/usr/lib/gcc/x86_64-linux-gnu/4.9/../../.. /tmp/ccGkw2Rn.o -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed
/tmp/ccGkw2Rn.o: In function `_start':
(.text+0x21): undefined reference to `esp'
collect2: error: ld returned 1 exit status
I am using 64 bit debian jessie. Surely, there is some way to compile 32 bit asm programs on 64 bit machines? Preferably with gas and ld. A gcc command would also be helpful.I got these commands from other stackoverflow posts that were also having trouble compiling 32 bit assembly programs on 64 bit machines. I must be missing something... Please help. Thank you.
Moving the comment to an 'answer' (since apparently I guessed correctly):
Depending on the assembler, it may be necessary to prefix register names with a % sign (ie %esp).