[U-Boot] [PATCH 0/4] Accurate boot time measurement

[Wolfgang Denk]

Dear Graeme Russ,

In message <BANLkTim7=-rZa_L-Dy0B-+aDqv4ngOLb-g at mail.gmail.com> you wrote:
>
> But at 9600 baud it is over 1ms - 9600 is still considered the lowest
> common denominator for serial comms for diagnostic output for a lot of
> devices such as industrial PLCs etc.

I think in the last 5 years I have seen but 2 devices using 9600 bps.
All others appear to be using 115200 bps these days.

And even at 9600 we're still close to millisecond reolution...

> And in the field, you may be interested more in transient timing anomalies
> which may result from network issues if the device is obtaining an IP address
> or loading an image file. In such scenarios, you will need to log the boot
> timing of every boot, not just when a serial terminal is connected

time-stamping console output is not restricted to the serial port.  It
works as well with tty over USB, or netconsole, or even netconsole
over USB.

> And finally, the lack of a serial port is a biggie - There are devices out
> there that do not have serial ports

If they have a console interface, then the output can be time-stamped.


Best regards,

Wolfgang Denk

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