logging.md

OpenVMM Logging

Configuring the logging messages to emit

To configure logging, use the OPENVMM_LOG environment variable. For example:

Enables debug events from all modules:

set OPENVMM_LOG=debug

Enables trace events from the mesh crate and info events from everything else:

set OPENVMM_LOG=info,mesh=trace

This is backed by the EnvFilter type; see the associated documentation for more details.

Capturing the ETW traces on the host

On Windows, OpenVMM also logs to ETW, via the Microsoft.HvLite provider.

To capture the trace first need to start the session:

logman.exe start trace <SessionName> -ow -o FileName0.etl -p "{22bc55fe-2116-5adc-12fb-3fadfd7e360c}" 0xffffffffffffffff 0xff -nb 16 16 -bs 16 -mode 0x2 -ets

For OpenHCL traces, use {AA5DE534-D149-487A-9053-05972BA20A7C} as the provider GUID.

To flush:

logman.exe update <SessionName> -ets -fd

To stop:

logman.exe stop <SessionName> -ets

To decode as CSV:

tracerpt.exe <FileName0>.etl -y -of csv -o <FileName1>.csv -summary <FileName2>.summary