I am on Mac Os X and I am having trouble compiling a .s ARM assembly file.
my .s file is this:
mov r0, r1
just to see if it works.
but when i do
arm-elf-as my.s
i get an
a.out file.
i do
chmod +x a.out
and
./a.out
but it says
cannot execute binary file
this has me confused, because it should be able to execute if i compiled it with arm-elf-as. How do i go about compiling this .s?
You're assembling it allright, you just can't run it on a Mac since Macs don't have ARM CPUs. If you install Xcode with iOS support, you can compile ARM code:
# the file
$ cat foo.s
mov r0, r1
# compile with llvm-gcc
$ /Developer/Platforms/iPhoneOS.platform/usr/bin/llvm-gcc-4.2 -arch armv6 -c foo.s
# resulting file is ARM object file
$ file foo.o
foo.o: Mach-O object arm
# and you can disassemble it
$ otool -v -t foo.o
foo.o:
(__TEXT,__text) section
00000000 e1a00001 mov r0, r1
You won't be able to run anything, because for that you'll need a runtime system and and ARM CPU. You can use -isysroot /Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.2.sdk or similar to compile for the iPhoneOS for example.
Related
I wrote simple x86 assembly routine:
$ cat asm.s
.global foo
.section .text
foo:
nop
ret
And compiled it with
$ gcc -c -g asm.s -o asm.o
But when I do objdump --dwarf asm.o, it does not display any info about function foo. Looks like, gcc does not create .debug_info details about foo.
BTW, there is a entry of foo in .symtab.
Any ideas?
The error is in the objdump command. use the following command, and it will show the assembly listing of your function:
objdump -d -M intel -S asm.o
Now you updated the question - if you want to include debug info then invoke the assembler with:
gcc -gdwarf2 -c asm.s -o asm.o
Now objdump --dwarf will display the debug info.
My base assembler file foidlrt.asm started getting a bit too large so I broke it up into two. Here is the entirety of the second file folder_stdio.asm:
; foidl_stdio.asm
%include "foidlstnd.inc"
section .text
DEFAULT REL
global foidl_fclose ; Raw file close
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; foidl_close
; Raw file close
; REGISTERS (1):
; RDI file handle
; CALLS:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
foidl_fclose:
mov rax,SYSCALL_FILE_CLOSE ; 0x2000006
syscall
ret
However, now when I build I am now getting this error from make despite the global declaration in the new file:
nasm src/foidlrt.asm -f macho64 --prefix _ -g -O0 -Iincludes/ -o asmobjs/foildrt.o
nasm src/foidlrt.asm -f macho64 --prefix _ -g -O0 -Iincludes/ -o asmobjs/foidl_stdio.o
libtool -static -s -o libs/libfoidlrt.a asmobjs/foildrt.o asmobjs/foidl_stdio.o
gcc src/testlink.c -L libs -l foidlrt -Wall -g -L. -Wl,-pie -I. -o bin/testlink
Undefined symbols for architecture x86_64:
"_foidl_fclose", referenced from:
_main in testlink-4b5ad3.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Version information:
XCode - 7.2.1 (7C1002)
nasm - NASM version 2.12 compiled on Feb 28 2016
gcc - Apple LLVM version 7.0.2 (clang-700.1.81)
RESOLVED
Error was all mine, makefile rule was bad. Working as expected now.
I'm trying to learn assembly and I'm using Nasm v2.10.07 on Mac OS X (Snow Leopard).
I can compile, but I need to read the Debug file, that is a .o file.
This is what I compile:
global _main
section.data
M db 5,4,3,2,1
dim equ $-M
section.text
_main:
mov edi, M
mov eax, 0
mov ebx, 1
int 80h
This is how I compile:
nasm -f elf -g -F stabs myfile.asm -o myfile.o
And this is the result:
ELF����������������������#�������4�����(�
�������������������������������������������������������������������–������������������������������������?��������������������������������0��M��������������������������������Ä��ê���������������"����������������2������������������*��� �����������P�����������������4��������������`��T����������������:��������������¿��������������������C��� �����������–��0���������������ø����∏����ª���ÕÄ�%define $�The Netwide Assembler 0.98.40 (Apple Computer, Inc. build 11)���.text�.comment�.shstrtab�.symtab�.strtab�.rel.text�.stab�.stabstr�.rel.stab��%d����������������������������Òˇ�������������Òˇ������������������������������������������������������Òˇ�������������,�������������myfile.asm�section.data�M�dim�section.text�_main��%define $_%1 ������%define������������d�����������D����������D���������D��
�������D� ��������D�
�����%define $_%�myfile.asm��%de����� �����,�����8�����D�����P�����
So, what should I do to read in the correct way the debug without those strange symbols?
To show the contents of the .stabs section, use objdump -g myfile.o or objdump -G myfile.o
To get the full source code with line numbers taken from the debug section, use objdump -S -l myfile.o
I am getting a linking error when compiling the numpy library against lapack indicating I need to compile lapack with -fPIC. I thought I had done just that. Is there a way to determine that the produced lapack library is position independent?
You may have some luck with this answer, although it's platform dependent and doesn't work for all object files (but if you code manipulates pointers in any way, it should work).
This is the result of objdump -r on a file compiled with -fPIC:
test.o: file format elf32-i386
RELOCATION RECORDS FOR [.text]:
OFFSET TYPE VALUE
00000007 R_386_PC32 __i686.get_pc_thunk.cx
0000000d R_386_GOTPC _GLOBAL_OFFSET_TABLE_
and this is for a file without PIC:
test.o: file format elf32-i386
In general, you have no way of knowing:
$ cat a.c
int foo(int x) { return x+1; }
$ gcc -fno-pic a.c -c -o nopic.o
$ gcc -fPIC a.c -c -o pic.o
$ cmp pic.o nopic.o
$ cmp pic.o nopic.o && echo Identical
Identical
i have some problems with linking nasm program for macos:
GLOBAL _start
SEGMENT .text
_start:
mov ax, 5
mov bx, ax
mov [a], ebx
SEGMENT .data
a DW 0
t2 DW 0
fry$ nasm -f elf test.asm
fry$ ld -o test test.o -arch i386
ld: warning: in test.o, file was built for unsupported file format which is not the architecture being linked (i386)
ld: could not find entry point "start" (perhaps missing crt1.
fry$ nasm -f macho test.asm
fry$ ld -o test test.o -arch i386
ld: could not find entry point "start" (perhaps missing crt1.o)
can anyone help me?
The Mac OS X linker can't link ELF objects. It works only with the Mach-O executable format. Unless you want to figure out how to translate the object files, you'll probably be better off writing code that works with the Mac OS X assembler.
Edit: As #Fry mentions in the comment below, you can make nasm put out Mach-O objects. In that case, the problem is simple - take the _ off of _start in both places in your source file. The result links fine.
nasm -f macho test.asm
ld -e _start -o test test.o
For people who need to stick with the elf format and develop on a mac, you need a cross compiler...
http://crossgcc.rts-software.org/doku.php?id=compiling_for_linux
Then you can proceed with something similar to this...
/usr/local/gcc-4.8.1-for-linux32/bin/i586-pc-linux-ld -m elf_i386 -T link.ld -o kernel kasm.o kc.o