CacheMetadataError when loading overlay

[rderi]

I have been trying to run the emulator on my PYNQ-Z2 board, but before the overlay loads, I keep encountering the same CacheMetadataError. I am using this repository for a class project, and I would really appreciate some help troubleshooting. The program's output is:

[2022-10-22 03:55:53,880][INFO] Loading Pynq libraries...
[2022-10-22 03:56:03,622][INFO] Finished loading Pynq libraries
[2022-10-22 03:56:04,176][INFO] Loading overlay...
[2022-10-22 03:56:04,190][DEBUG] Using selector: EpollSelector
Traceback (most recent call last):
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynq/pl_server/embedded_device.py", line 252, in get_parser
    parser = self._get_cache() 
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynq/pl_server/embedded_device.py", line 228, in _get_cache
    raise CacheMetadataError(f"No cached metadata present")
pynq.pl_server.embedded_device.CacheMetadataError: No cached metadata present

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/home/xilinx/final/gameboy_ps/__main__.py", line 17, in <module>
    system = system.System(rom_directory)
  File "/home/xilinx/final/gameboy_ps/system.py", line 15, in __init__
    self.gameboy = Gameboy()
  File "/home/xilinx/final/gameboy_ps/gameboy.py", line 72, in __init__
    self.overlay = Overlay(str(overlay_path))
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynq/overlay.py", line 319, in __init__
    self.device.set_bitfile_name(self.bitfile_name)
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynq/pl_server/device.py", line 118, in set_bitfile_name
    self.parser = self.get_bitfile_metadata(self.bitfile_name)
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynq/pl_server/embedded_device.py", line 690, in get_bitfile_metadata
    parser = _get_bitstream_handler(bitfile_name).get_parser(partial=partial)
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynq/pl_server/embedded_device.py", line 254, in get_parser
    parser = RuntimeMetadataParser(Metadata(input=self._filepath.with_suffix(".hwh")))
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynqmetadata/frontends/metadata.py", line 40, in Metadata
    return HwhFrontend(_hwhfile=input)
  File "<string>", line 25, in __init__
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynqmetadata/frontends/hwh_frontend.py", line 219, in __post_init__
    self.parse()
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynqmetadata/frontends/hwh_frontend.py", line 240, in parse
    self.resolve_addressing()
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynqmetadata/frontends/hwh_frontend.py", line 596, in resolve_addressing
    self._resolve_subordinate_addressing()
  File "/usr/local/share/pynq-venv/lib/python3.10/site-packages/pynqmetadata/frontends/hwh_frontend.py", line 452, in _resolve_subordinate_addressing
    core = self.blocks[i.get("INSTANCE")]
KeyError: 'M_AXI_0'

Additional info:

• Using v3.0.1 of the PYNQ-Z2 SD card image
• Using the precompiled bitstream
• Tested with multiple ROM files
• Followed set-up instructions: moved gameboy.bit and gameboy.hwh to gameboy_ps/resources; loaded xpad and joydev drivers from the repo's extra directory; installed required Python packages

[elipsitz]

Oh, this sounds familiar. I think the Pynq libraries distributed with v3.0.1 are slightly outdated.

I’m pretty sure you need this commit: Xilinx/PYNQ-Metadata@d67f1bf

You can try temporarily modifying /usr/local/share/pynq-venv/lib/python3.10/site-packages/pynqmetadata/frontends/hwh_frontend.py with the changes and see if that fixes it. And then if it does, do a proper pip install from that repo. Let me know if that works, and I can update the instructions. Hopefully I didn’t have to make any other changes to the Pynq libraries, but I’ll try to see.

Out of curiosity, what’s the class project?

[bzob]

I had the same problem. I changed hwh_frontend.py according to what @elipsitz mentioned above and that fixed it.

[rderi]

Sorry, I forgot to get back—the fix also worked for me.