Command line arguments are not passed correctly with user-space semihosting
Host environment
- Operating system: Ubuntu 20.04 WSL2 on Windows 10 (also experienced on native Ubuntu 20.04 and containerised)
- OS/kernel version: Linux 5.4.72-microsoft-standard-WSL2 #1 SMP Wed Oct 28 23:40:43 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
- Architecture: x86_64
- QEMU flavor:
qemu-arm
- QEMU version: qemu-arm version 6.1.90 (v6.2.0-rc0-10-gb30187ef)
- QEMU command line:
$ qemu-arm -cpu cortex-m7 ./a.out 123 test
Emulated/Virtualized environment
- Using user-space emulation
Description of problem
The emulated process always receives a value of 1 for argc
, with argv[0]
returning seemingly random characters (in Ubuntu packaged qemu 5.2), but correlating with command-line input (output below from master built qemu 6.1):
$ qemu-arm -cpu cortex-m7 ./a.out 123 test
argc: 1
argv:
- @@@
$ qemu-arm -cpu cortex-m7 ./a.out
argc: 1
argv:
[0] @
Steps to reproduce
- Compile the following program with ARM embedded toolchain:
#include <iostream>
int main(int argc, char* argv[]) {
std::cout << "argc: " << argc << "\n";
std::cout << "argv: \n";
for (int i = 0; i < argc; i++)
std::cout << " [" << i << "] " << argv[i] << "\n";
return 0;
}
$ $CXX --version
arm-none-eabi-g++ (GNU Arm Embedded Toolchain 10-2020-q4-major) 10.2.1 20201103 (release)
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.
$ $CXX main.cpp --specs=rdimon.specs -mcpu=cortex-m7
- Run in user-space (semihosted):
$ qemu-arm -cpu cortex-m7 ./a.out