All Volt components expose logging capabilities which can produce extensive diagnostic information for use in troubleshooting and debugging scenarios.

Environment variables

The logging mode and verbosity is controlled via two environment variables.

The TDXVOLT_LOG_LEVEL environment variable configures the overall logging mode, and can take either ERROR or DEBUG values. The default value, if no environment variable is found, is dependent on the build mode - see below.

The TDXVOLT_LOG_DEBUG environment variable can be used to control the verbosity of output when using the DEBUG log level. This variable can take various values as indicated in the table below:

allAll components emit output.
clientC++ client library components.
coreThe Volt core components.
cryptoAll cryptographic-related output.
databaseOutput related to the Volt meta-database. This can be quite noisy.
fuseboxFusebox-specific debug output.
grpc-clientClient-side grpc diagnostics.
grpc-serverServer-side grpc diagnostics.
perfomancePerformance and timing data across the platform.
policyPolicy evaluation diagnostics, this can be quite noisy.
qmlDiagostics originating from QML code. This is only used by the fusebox.

The TDXVOLT_LOG_DEBUG variable can be used to pick and mix output from various debug components. A component can be omitted from the output by prefixing the name with a minus sign.

Terminal window
# Request all DEBUG information apart from policy and database output.
export TDXVOLT_LOG_DEBUG=all,-policy,-database
Terminal window
# Request crypto debug output.
export TDXVOLT_LOG_DEBUG=crypto

If the TDXVOLT_LOG_DEBUG variable is unset and TDXVOLT_LOG_LEVEL is set to DEBUG then by default all component output is generated, which is equivalent to TDXVOLT_LOG_DEBUG=all.

Note that the `TDXVOLT_LOG_DEBUG` variable only affects `DEBUG` output. The `ERROR` output will be generated for all components irrespective of the value of `TDXVOLT_LOG_DEBUG`.

Release builds

The default log level for release builds is ERROR, and the output is written to a file in the ~/Documents/tdxVolt/logs folder, or equivalent depending on the OS.

The log output is never written to STDOUT when using release builds.

The log level can be increased to DEBUG via the TDXVOLT_LOG_LEVEL environment variable, and similarly the TDXVOLT_LOG_DEBUG variable can be used to configure the verbosity of the various components, as outlined above.

Debug builds

The default log level for debug builds is DEBUG, and the output is written to STDOUT, as well as a file in the ~/Documents/tdxVolt/logs folder, or equivalent depending on the OS.

The default verbosity level all, so all components will output debug information.


It is possible to enable grpc logging in addition to that of the Volt. This can be done using the GRPC_VERBOSITY and GRPC_TRACE environment variables, see this document for more information.