Advanced users • Re: Running 32bit ELF executables on 64bit Pi OS

strace -i gives us just enough information to debug the crash:

Code:

[b5923158] --- SIGBUS {si_signo=SIGBUS, si_code=BUS_ADRALN, si_addr=0xb652517f} ---

The instruction at 0x158 bytes into the binary is the ldr here:

Code:

      9c:       e305c17f        movw    ip, #20863      @ 0x517f      a0:       e34bc652        movt    ip, #46674      @ 0xb652      a4:       e59cf000        ldr     pc, [ip]

I am used to SIGBUS meaning that we went outside the extent of an mmapped file (usually because the disk is full), but this is a straightforward alignment issue. readelf confirms that the .got in the binary is misaligned:

Code:

  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al  [10] .got              PROGBITS        b6525173 001173 000018 04  WA  0   0  4

How does this work in a 32bit distro? I think it might actually depend on the CPU model. I can only reproduce a bus error when attempting a misaligned read directly to PC. Reading to a different register first and then moving appears to hide the problem.

As a follow up, your info above allowed me to fix the alignment issue in about 30 minutes of work. I pushed the alignment fix a few days ago. Thanks again.

I will try your Bookworm64 "shared library install" fix on the Pi 500 to enable 32 bit ELF executables to run on the PI 500 shortly, after I further "clean up" my ELF file creation code. I will also update my Makefile at that point to run on any machine with the proper 32 bit eabi-hf environment installed.

Frankly, I'm surprised the package installation process for the 32 bit compile/execution environment on the 64 bit OS is not described somewhere within the raspberrypi.com Documentation tab. I'm betting it will be as simple as three "sudo apt install" commands, back-to-back.

Statistics: Posted by HPCguy — Wed Apr 30, 2025 1:32 am

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