[BUG] xtensa-build-zephyr.py fails to sign fw image using private key with relative path

[aborisovich]

Describe the bug
During firmware building using xtensa-build-zephyr.py script, rimage fails to generate final sof-mtl.ri image file with error

"mtl_private_key.pem: error: unable to open file for reading. No such file or directory (errno = 2)"

To Reproduce
Run building command (in "west top" directory):
python sof\scripts\xtensa-build-zephyr.py mtl -k mtl_private_key.pem

Reproduction Rate
100%.

Expected behavior
Rimage generates signed sof-mtl.ri file in build-sof-staging directory.

Workaround
Run building command (in "west top" directory) with absolute path to the private key:
python sof\scripts\xtensa-build-zephyr.py mtl -k C:\Workspace\my_sof_workspace\mtl_private_key.pem

Impact
Annoyance.

Environment

1. Branch name and commit hash of the 2 repositories: sof (firmware/topology) and linux (kernel driver).
   • Kernel: N/A
   • SOF: Main SHA: 40625f0
2. Name of the topology file
   • Topology: N/A
3. Name of the platform(s) on which the bug is observed.
   • Platform: MTL (other not tested)
4. Operating system:
   • Windows

Screenshots or console output
error.log

[aborisovich]

Bug is NOT reproduced on the commit: 2df3cba .
Based on the git history of xtensa-build-zephyr.py there are 2 more commits forward - that's where would start looking for the bug cause: 5a82b0a or a769d39 .
@marc-hb I think it may be related to your recent changes to rimage and west sign command.

[marc-hb]

thanks for @aborisovich for the very good bug report. Simple fix submitted in #7721