[coreboot] Fwd: use gcc 4.6.0 link time optimization to reduce coreboot execution time

Kevin O'Connor kevin at koconnor.net
Sun May 1 17:15:24 CEST 2011

On Sat, Apr 30, 2011 at 11:11:37PM -0500, Scott Duplichan wrote:
> Anton Kochkov wrote:
> ] May be add something like profiling option with patch for implementing
> ] such feature?
> ] Best regards,
> ] Anton Kochkov.
> Hello Anton,
> In the past I have seen such logging code added to a BIOS code base.
> It was for Phoenix legacy if I remember correctly. A challenge with 
> this method is using it to exactly pinpoint a problem. For this board

There is a tool in the seabios repo - tools/readserial.py .  It can be
run on a separate host that reads the debug serial output - it
provides timing info on each line read and can adjust the times to
eliminate the cost of writing to the serial port.

It's not perfect, but it can provide a broad overview of where time is

If you haven't already tried it, it's usage follows:

./tools/readserial.py /dev/ttyS0 115200

>For this board
> I have the luxury of a jtag debugging setup, the Sage SmartProbe. This
> arrangement is very handy for boot time reduction. I do a crude form
> of profiling by breaking in randomly during post. I still find it
> spending some time in lzma decode of ramstage. That time was reduced
> by the -flto compiler option. 

Thanks - I'll have to try that on my board (an old epia-cn machine).
I found lzma to be time intensive.


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