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armcross-compilinggnu-assembler

Assembling ARM instructions on x86_64

I have a file, foo.S, which contains ARM thumb instructions, on an Ubuntu 22.04 x86_64 machine. Is it possible to convert this into an ARM object file using as from binutils or do I need to create a cross-compiler toolchain? I tried

$ as -mthumb foo.S -o foo.o

However, I got

as: unrecognized option '-mthumb'

even though that's one of the options listed in man as.

Solution

  • run

    sudo sh -c 'apt update;apt install binutils-arm-none-eabi;'

    then the code can be compiled with

    arm-none-eabi-as -mthumb foo.S -o foo.o

    example:

    $ echo nop > foo.S 
$ arm-none-eabi-as -mthumb foo.S -o foo.o
$ echo $?
0
$ file foo.o
foo.o: ELF 32-bit LSB relocatable, ARM, EABI5 version 1 (SYSV), not stripped
    • i gathered this from @Nate Eldredge and @old_timer in the comments.