Update the debugging documentation with info on timing debug output with readserial.py.
Signed-off-by: Kevin O'Connor kevin@koconnor.net --- docs/Debugging.md | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+)
diff --git a/docs/Debugging.md b/docs/Debugging.md index d651fc9..1ba56af 100644 --- a/docs/Debugging.md +++ b/docs/Debugging.md @@ -34,6 +34,43 @@ To report an issue, please collect the serial boot log with SeaBIOS set to a debug level of 8 and forward the full log along with a description of the problem to the SeaBIOS [mailing list](Mailinglist).
+Timing debug messages +===================== + +The SeaBIOS repository has a tool (**scripts/readserial.py**) that can +timestamp each diagnostic message produced. The timestamps can provide +some additional information on how long internal processes take. It +also provides a simple profiling mechanism. + +The tool can be used on coreboot builds that have diagnostic messages +sent to a serial port. Make sure SeaBIOS is configured with +CONFIG_DEBUG_SERIAL and run the following on the host receiving serial +output: + +`/path/to/seabios/scripts/readserial.py /dev/ttyS0 115200` + +Update the above command with the appropriate serial device and baud +rate. + +The tool can also timestamp the messages from the QEMU debug port. To +use with QEMU run the following: + +`mkfifo qemudebugpipe`\ +`qemu -chardev pipe,path=qemudebugpipe,id=seabios -device isa-debugcon,iobase=0x402,chardev=seabios ...` + +and then in another session: + +`/path/to/seabios/scripts/readserial.py -nf qemudebugpipe` + +The mkfifo command only needs to be run once to create the pipe file. + +When readserial.py is running, it shows a timestamp with millisecond +accuracy of the amount of time since the start of the log. If one +presses the "enter" key in the readserial session it will add a blank +line to the screen and also reset the time back to zero. The +readserial.py program also keeps a log of all output in files that +look like "seriallog-YYYYMMDD_HHMMSS.log". + Debugging with gdb on QEMU ==========================
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Kevin O'Connor