From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Denk Date: Mon, 16 May 2011 07:55:03 +0200 Subject: [U-Boot] [PATCH 0/4] Accurate boot time measurement In-Reply-To: References: <1305319923-9477-1-git-send-email-sjg@chromium.org> <20110515115317.56695DB7945@gemini.denx.de> Message-ID: <20110516055503.81F381491B07@gemini.denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Dear Graeme Russ, In message 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 -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de To know how another being, another creature feels - that is impos- sible. - Terry Pratchett, _The Dark Side of the Sun_