elf2uf2 on s390x: ERROR: Not an ELF file

[josch]

Hi,

I have this CMakeLists.txt:

cmake_minimum_required(VERSION 3.13)
include(pico_sdk_import.cmake)
project(hello_world)
pico_sdk_init()

add_executable(hello_world hello.c)
target_link_libraries(hello_world pico_stdlib)
pico_add_extra_outputs(hello_world)

and this hello-world program (yes this program is not even making use of the pico sdk but the problem is also there if we add that):

#include <stdio.h>

int main() {
    printf("Hello, world!\n");
    return 0;
}

On s390x the build will fail like this:

$ make VERBOSE=1
[...]
/usr/bin/arm-none-eabi-objcopy -Oihex /home/josch/hello_world.elf hello_world.hex
/usr/bin/arm-none-eabi-objcopy -Obinary /home/josch/hello_world.elf hello_world.bin
/usr/bin/arm-none-eabi-objdump -h /home/josch/hello_world.elf > hello_world.dis
/usr/bin/arm-none-eabi-objdump -d /home/josch/hello_world.elf >> hello_world.dis
elf2uf2/elf2uf2 /home/josch/hello_world.elf hello_world.uf2
ERROR: Not an ELF file
make[2]: *** [CMakeFiles/hello_world.dir/build.make:812: hello_world.elf] Error 254
make[2]: *** Deleting file 'hello_world.elf'
make[2]: Leaving directory '/home/josch'
make[1]: *** [CMakeFiles/Makefile2:1491: CMakeFiles/hello_world.dir/all] Error 2
make[1]: Leaving directory '/home/josch'
make: *** [Makefile:91: all] Error 2

I added some printfs into tools/elf2uf2/main.cpp to investigate the values of ELF_MAGIC and eh_out.common.magic in read_and_check_elf32_header and got this:

ELF_MAGIC = 464c457f
eh_out.common.magic = 7f454c46

There seems to be an endian problem somewhere? The file utility seems to think that my hello_world.elf has the correct magic:

$ file hello_world.elf
hello_world.elf: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, with debug_info, not stripped

Any ideas?