The actual error seems to be hidden, and only "private" is displayed. I noticed that the same thing happens if a formatting string for string types is used in log messages, obviously due to security reasons.   2022-05-24 08:46:16.759215+0200 0xfff2   Default   0x0         0   0  kernel: (com.mycompany.mydriver) <private>     Another error is logged when the driver tries to access a file outside of the bundle path. But this is irrelevant, as you say that only files inside the bundle are accessible. 2022-05-24 08:46:16.759301+0200 0xfff2   Error    0x0         0   0  kernel: (Sandbox) Sandbox: com.mycompany.mydriver(5517) deny(1) file-read-data /Library/Application Support/mycompany/cooldriver/configfile.conf Opening the Info.plist doesn't work for me. Should be specified a full or a relative path? Passing a full path is a bit tricky, as I do not have control over the path from which the driver runs (according to Activity monitor: /Library/SystemExtensions//com.mycompany.mydriver.dext/com.mycompany.mydriver) after it is installed.

EDIT: the path should have been (according to Activity monitor: /Library/SystemExtensions/RANDOM_GUID/com.mycompany.mydriver.dext/com.mycompany.mydriver)

The question is, how to find out the full bundle path, which is passed to OSMappedFile::createFromPath? Its path is different with every build, so it can't be hardcoded. Relative paths don't seem to work either. Passing the path from a client app via IOUserClient class is not a solution for me, as I would like to read the file in driver's Start() method