-sh: no such file or directory

root@bmc:~# /usr/local/bin/phosphor-psu-monitor -c /usr/local/share/phosphor-psu-monitor/bmc_psu_config.json
-sh: /usr/local/bin/phosphor-psu-monitor: No such file or directory
root@bmc:~# ls -l /usr/local/bin
-rwxr-x--x    1 root     root       6004032 Jan 10 23:18 phosphor-psu-monitor

OpenBMC supports several generations of BMC SoCs. In the case of ASPEED BMC SoCs, each generation has moved forward with the supported ISA and hardware features, and the ARMv7 AST2600 now sports hard-float support in the form of vfpv4d16.

Switching from the soft-float strategy of previous generations to the hard-float strategy supported by hardware in the AST2600 requires a change of kernel configuration and binary ABI options passed to the compiler for an application if the base system software has been configured for hard-float. If we use the wrong ABI we end up with the cryptic output provided above, which is telling us that the kernel cannot find the right handler for the binary.

In the case of ELF binaries, we can use readelf --dynamic as a system-independent way to determine the libraries that need to be loaded (as opposed to ldd, which you might want to be cautious of using anyway):

$ readelf --dynamic phosphor-psu-monitor | grep NEEDED
 0x00000001 (NEEDED)                     Shared library: [libsdbusplus.so.1]
 0x00000001 (NEEDED)                     Shared library: [libsystemd.so.0]
 0x00000001 (NEEDED)                     Shared library: [libsdeventplus.so.0]
 0x00000001 (NEEDED)                     Shared library: [libstdc++.so.6]
 0x00000001 (NEEDED)                     Shared library: [libgcc_s.so.1]
 0x00000001 (NEEDED)                     Shared library: [libc.so.6]
 0x00000001 (NEEDED)                     Shared library: [ld-linux-armhf.so.3]

The final entry here is ld-linux-armhf.so.3 - this binary will work on our hard-float-enabled systems. This is in contrast to:

$ readelf -d phosphor-psu-monitor | grep NEEDED
 0x00000001 (NEEDED)                     Shared library: [libsdbusplus.so.1]
 0x00000001 (NEEDED)                     Shared library: [libsystemd.so.0]
 0x00000001 (NEEDED)                     Shared library: [libsdeventplus.so.0]
 0x00000001 (NEEDED)                     Shared library: [libstdc++.so.6]
 0x00000001 (NEEDED)                     Shared library: [libgcc_s.so.1]
 0x00000001 (NEEDED)                     Shared library: [libc.so.6]
 0x00000001 (NEEDED)                     Shared library: [ld-linux.so.3]

This binary is looking for ld-linux.so.3, which is not present on the hard-float-enabled images, and its absence is the reason we get no such file or directory.

If you encounter this problem with OpenBMC make sure you are using the right SDK for the system you’re building binaries for and that you are not moving back-and-forth between images that switch between soft- and hard-float strategies.