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Prior to Windows Vista, the debug version of Avc.sys permits trace messages to be output to a debug window. The Windows Vista version of Avc.sys uses Event Tracing for Windows (ETW).
The AvcDebugLevel ULONG type is a bitmap of possible trace levels. Each nibble represents a category of trace output. The default value is 0x00CCCCCC, which sets all message categories to ERROR and WARNING output levels. The best setting to monitor AV/C command activity is 0x000ECCCC (adds the TRACE class of messages to the AV/C category of output). To turn off all debug output, set all bits to 0. The bitmaps for each category are described below.
Generic Message Category
The GENERIC category applies to all generic output. The most interesting class of output is FLOW that, when enabled, logs a message at each function's entry and exit points. On computers running Windows Millennium Edition (Windows Me), Windows 98, or Windows 95, all TL_FLOW (and most TL_TRACE messages) go to the .ntkern circular buffer pool. To see these log entries, use type .ntkern in the debugger, and select the D option. Press the SPACEBAR after pressing D to continue dumping the buffer, one page at a time. Press any other key to cancel the dump. To turn off the .ntkern logging and send the messages to the standard debug output, use the e ulind debugger command to set the ulind variable to 1 (the default setting is 0).
| Meaning | Value |
|---|---|
TL_MASK |
0x0000000F |
TL_FLOW |
0x00000001 |
TL_TRACE |
0x00000002 |
TL_WARNING |
0x00000004 |
TL_ERROR |
0x00000008 |
Plug and Play Message Category
The Plug and Play (PnP) category applies to all output related to PnP.
| Meaning | Value |
|---|---|
TL_PNP_MASK |
0x000000F0 |
TL_PNP_TRACE |
0x00000020 |
TL_PNP_WARNING |
0x00000040 |
TL_PNP_ERROR |
0x00000080 |
Power Management Message Category
The Power Management category applies to all output related to power management, including hibernation.
| Meaning | Value |
|---|---|
TL_POWER_MASK |
0x00000F00 |
TL_POWER_TRACE |
0x00000200 |
TL_POWER_WARNING |
0x00000400 |
TL_POWER_ERROR |
0x00000800 |
I/O Message Category
The I/O category applies to all output related to interdriver communication, including IRP processing.
| Meaning | Value |
|---|---|
TL_IO_MASK |
0x0000F000 |
TL_IO_NOISE |
0x00001000 |
TL_IO_TRACE |
0x00002000 |
TL_IO_WARNING |
0x00004000 |
TL_IO_ERROR |
0x00008000 |
AV/C Message Category
The AV/C category applies to all output that is related to AV/C commands, plus some internal driver messages of potential relevance to object lists and spin locks (TL_IO_NOISE I/O Message Category). Included in the TL_IO_TRACE category of messages are command execution times.
| Meaning | Value |
|---|---|
TL_AVC_MASK |
0x000F0000 |
TL_AVC_NOISE |
0x00010000 |
TL_AVC_TRACE |
0x00020000 |
TL_AVC_WARNING |
0x00040000 |
TL_AVC_ERROR |
0x00080000 |
Connection Message Category
The Connection category deals with all plug connection-related output.
| Meaning | Value |
|---|---|
TL_CXN_MASK |
0x00F00000 |
TL_CXN_NOISE |
0x00100000 |
TL_CXN_TRACE |
0x00200000 |
TL_CXN_WARNING |
0x00400000 |
TL_CXN_ERROR |
0x00800000 |