QEMU semihosting doesn't produce output

Question

I'm trying to set up a testing environment for my project using semihosting within QEMU. So far I had no issues with hello.c following this answer, however I'm having trouble getting it to work with CMake.

Here's how I'm building the exact same hello.c (toolchain file on pastebin):

C:\hello_cmake>cmake -G"Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake . -Btmp
-- The C compiler identification is GNU 10.3.1
-- The CXX compiler identification is GNU 10.3.1
-- Configuring done
-- Generating done
-- Build files have been written to: C:/hello_cmake/tmp

C:\hello_cmake>cmake --build tmp --verbose
"C:/Program Files/CMake/bin/cmake.exe" -SC:/hello_cmake -BC:/hello_cmake/tmp --check-build-system CMakeFiles/Makefile.cmake 0
"C:/Program Files/CMake/bin/cmake.exe" -E cmake_progress_start C:/hello_cmake/tmp/CMakeFiles C:/hello_cmake/tmp//CMakeFiles/progress.marks
C:/buildtools/bin/make.exe  -f CMakeFiles/Makefile2 all
make.exe[1]: Entering directory 'C:/hello_cmake/tmp'
C:/buildtools/bin/make.exe  -f CMakeFiles/hello.dir/build.make CMakeFiles/hello.dir/depend
make.exe[2]: Entering directory 'C:/hello_cmake/tmp'
"C:/Program Files/CMake/bin/cmake.exe" -E cmake_depends "Unix Makefiles" C:/hello_cmake C:/hello_cmake C:/hello_cmake/tmp C:/hello_cmake/tmp C:/hello_cmake/tmp/CMakeFiles/hello.dir/DependInfo.cmake --color=
make.exe[2]: Leaving directory 'C:/hello_cmake/tmp'
C:/buildtools/bin/make.exe  -f CMakeFiles/hello.dir/build.make CMakeFiles/hello.dir/build
make.exe[2]: Entering directory 'C:/hello_cmake/tmp'
[ 50%] Building C object CMakeFiles/hello.dir/hello.c.obj
"C:/Program Files (x86)/GNU Arm Embedded Toolchain/10 2021.10/bin/arm-none-eabi-gcc.exe"   -specs=rdimon.specs -mcpu=cortex-a9 -O0 -g -MD -MT CMakeFiles/hello.dir/hello.c.obj -MF CMakeFiles/hello.dir/hello.c.obj.d -o CMakeFiles/hello.dir/hello.c.obj -c C:/hello_cmake/hello.c
[100%] Linking C executable hello
"C:/Program Files (x86)/GNU Arm Embedded Toolchain/10 2021.10/bin/arm-none-eabi-gcc.exe"  -lc -lrdimon -lc -lrdimon "CMakeFiles/hello.dir/hello.c.obj"  -o hello
make.exe[2]: Leaving directory 'C:/hello_cmake/tmp'
[100%] Built target hello
make.exe[1]: Leaving directory 'C:/hello_cmake/tmp'
"C:/Program Files/CMake/bin/cmake.exe" -E cmake_progress_start C:/hello_cmake/tmp/CMakeFiles 0

And here's how I invoke QEMU:

qemu-system-arm.exe -nographic -machine xilinx-zynq-a9 -cpu cortex-a9 -monitor none -serial stdio -kernel app -m 512 -semihosting

QEMU almost immediately exits without producing any output, however -d exec and -d init logs look like code is running and semihosting actually works:

...
Trace 0: 0000000004705540 [00000400/0000828c/000005a0/ff000000] __libc_init_array
Trace 0: 0000000004705780 [00000400/000081ec/000005a0/ff000000] frame_dummy
Trace 0: 00000000047058c0 [00000400/00010460/000005a0/ff000000] main
Trace 0: 0000000004705c00 [00000400/00029158/000005a0/ff000000] printf
Trace 0: 0000000004706040 [00000400/000301f0/000005a0/ff000000] _vfprintf_r
Trace 0: 0000000004706440 [00000400/000375b8/000005a0/ff000000] _localeconv_r
Trace 0: 00000000047065c0 [00000400/0003020c/000005a0/ff000000] _vfprintf_r
Trace 0: 00000000047067c0 [00000400/0000a704/000005a0/ff000000] strlen
...

Taking exception 16 [Semihosting call] on CPU 0
...from EL1 to EL0
...handling as semihosting call 0xc
Taking exception 16 [Semihosting call] on CPU 0
...from EL1 to EL0
...handling as semihosting call 0x13
Taking exception 16 [Semihosting call] on CPU 0
...from EL1 to EL0
...handling as semihosting call 0x5
Taking exception 16 [Semihosting call] on CPU 0
...from EL1 to EL0
...

The question is: what does CMake do (or doesn't do) that breaks printf output?

For the record:

arm-none-eabi-gcc (GNU Arm Embedded Toolchain 10.3-2021.10)
QEMU emulator version 7.0.0 (v7.0.0-11902-g1d935f4a02-dirty)
Microsoft Windows [Version 10.0.19044.1645]
cmake version 3.22.2

` with the following options:` sooo where are you specyfing the compiler? Please post output of clean cmake configuration stage and verbose (`make VERBOSE=1` or `cmake --build .. --verbose`) output from cmkae build stage. — KamilCuk, May 11 '22 at 11:10
It would be helpful if you put together an MRE since you're so close to having one. Put the C source, CMakeLists.txt, the toolchain file, and the commands to reproduce _in the question_. — Alex Reinking, May 11 '22 at 17:59
Could you please augment your question with a mention of where you got make.exe from, and what is its version ? — Frant, May 11 '22 at 18:44

Frant · Accepted Answer · 2022-05-12T02:53:29.170

I was unable to find the CMakeLists.lst you are using, but I was able to produce/run hello.elf using the following files:

hello.c:

#include <stdlib.h>
#include <stdio.h>

int main(int argc, char** argv)
{
    printf("Hello, World!\n");
    return EXIT_SUCCESS;
}

CMakeLists.lst:

project(hello_world)
add_executable(hello.elf hello.c)

toolchain.cmake (removed -specs=rdimon.specs, since this is more a linking option, using --specs=rdimon.specs option for the linker - -lc is not needed, because redundant with the use of rdimon.specs):

set(CMAKE_SYSTEM_NAME       Generic)
set(CMAKE_SYSTEM_PROCESSOR  Cortex-A9)

# Common options
add_compile_options(
    -mcpu=cortex-a9
    -O0
    -g
)

set(CMAKE_EXE_LINKER_FLAGS "--specs=rdimon.specs")

set(CMAKE_C_COMPILER_FORCED TRUE)
set(CMAKE_CXX_COMPILER_FORCED TRUE)

find_program(CMAKE_C_COMPILER               $ENV{ARMGCC_DIR}/bin/arm-none-eabi-gcc.exe)
find_program(CMAKE_CXX_COMPILER             $ENV{ARMGCC_DIR}/bin/arm-none-eabi-g++.exe)
find_program(CMAKE_ASM_COMPILER             $ENV{ARMGCC_DIR}/bin/arm-none-eabi-gcc.exe)

find_program(CMAKE_OBJCOPY                  $ENV{ARMGCC_DIR}/bin/arm-none-eabi-objcopy)
find_program(CMAKE_OBJDUMP                  $ENV{ARMGCC_DIR}/bin/arm-none-eabi-objdump)
find_program(CMAKE_NM                       $ENV{ARMGCC_DIR}/bin/arm-none-eabi-nm)
find_program(CMAKE_LINKER                   $ENV{ARMGCC_DIR}/bin/arm-none-eabi-ld)

build-cmake.cmd:

@set ARMGCC_DIR=D:\opt\arm\10\gcc-arm-10.3-2021.07-mingw-w64-i686-arm-none-eabi
@set CMAKE=D:\opt\cmake-3.23.1-windows-x86_64\bin\cmake
@set MAKE=D:\opt\stackoverflow\72199730\make.exe
@set QEMU_SYSTEM_ARM=D:\opt\qemu-7.0.0\qemu-system-arm

%CMAKE% -E rm -rf tmp
%CMAKE% -G "Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake . -Btmp
%MAKE% -C tmp
%QEMU_SYSTEM_ARM%  -semihosting --semihosting-config enable=on,target=native -nographic -serial mon:stdio -machine xilinx-zynq-a9 -m 768M -cpu cortex-a9 -kernel tmp\hello.elf

Execution:

D:\opt\stackoverflow\72199730>build-cmake.cmd

D:\opt\stackoverflow\72199730>D:\opt\cmake-3.23.1-windows-x86_64\bin\cmake -E rm -rf tmp

D:\opt\stackoverflow\72199730>D:\opt\cmake-3.23.1-windows-x86_64\bin\cmake -G "Unix Makefiles" -DCMAKE_TOOLCHAIN_FILE=toolchain.cmake . -Btmp
-- The C compiler identification is GNU 10.3.1
-- The CXX compiler identification is GNU 10.3.1
-- Configuring done
-- Generating done
-- Build files have been written to: D:/opt/stackoverflow/72199730/tmp

D:\opt\stackoverflow\72199730>D:\opt\stackoverflow\72199730\make.exe -C tmp
make: Entering directory 'D:/opt/stackoverflow/72199730/tmp'
make[1]: Entering directory 'D:/opt/stackoverflow/72199730/tmp'
make[2]: Entering directory 'D:/opt/stackoverflow/72199730/tmp'
make[2]: Leaving directory 'D:/opt/stackoverflow/72199730/tmp'
make[2]: Entering directory 'D:/opt/stackoverflow/72199730/tmp'
[ 50%] Building C object CMakeFiles/hello.elf.dir/hello.c.obj
[100%] Linking C executable hello.elf
make[2]: Leaving directory 'D:/opt/stackoverflow/72199730/tmp'
[100%] Built target hello.elf
make[1]: Leaving directory 'D:/opt/stackoverflow/72199730/tmp'
make: Leaving directory 'D:/opt/stackoverflow/72199730/tmp'

D:\opt\stackoverflow\72199730>D:\opt\qemu-7.0.0\qemu-system-arm  -semihosting --semihosting-config enable=on,target=native -nographic -serial mon:stdio -machine xilinx-zynq-a9 -m 768M -cpu cortex-a9 -kernel tmp\hello.elf
Hello, World!

Versions used:

\opt\arm\10\gcc-arm-10.3-2021.07-mingw-w64-i686-arm-none-eabi\bin\arm-none-eabi-gcc --version
arm-none-eabi-gcc (GNU Toolchain for the A-profile Architecture 10.3-2021.07 (arm-10.29)) 10.3.1 20210621
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


\opt\cmake-3.23.1-windows-x86_64\bin\cmake.exe --version
cmake version 3.23.1

CMake suite maintained and supported by Kitware (kitware.com/cmake).

D:\opt\stackoverflow\72199730>\opt\qemu-7.0.0\qemu-system-arm.exe --version
QEMU emulator version 7.0.0 (v7.0.0-11902-g1d935f4a02-dirty)
Copyright (c) 2003-2022 Fabrice Bellard and the QEMU Project developers

make --version
GNU Make 4.2.1
Built for x86_64-w64-mingw32
Copyright (C) 1988-2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

wmic os get version
Version
10.0.19044

Hi @psykana, if this or any answer has solved your question please consider [accepting it](https://meta.stackexchange.com/q/5234/179419) by clicking the check-mark. This indicates to the wider community that you've found a solution and gives some reputation to both the answerer and yourself. There is of course no obligation to do this. — Frant, May 12 '22 at 02:53
You are right, my CMAKE_EXE_LINKER_FLAGS were wrong. Setting them to what you did here fixed everything. Thanks for your answer! — psykana, May 12 '22 at 07:29

QEMU semihosting doesn't produce output

1 Answers1

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