Hi Dave And Sandeep,<div><br></div><div>Hope I can contribute and sorry for the interruption of conversation :-(.<br><br><div class="gmail_quote">On Tue, Jan 10, 2012 at 2:59 PM, Dave Hylands <span dir="ltr"><<a href="mailto:dhylands@gmail.com">dhylands@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi sandeep,<br>
<div class="im"><br>
On Mon, Jan 9, 2012 at 10:37 PM, sandeep kumar<br>
<<a href="mailto:coolsandyforyou@gmail.com">coolsandyforyou@gmail.com</a>> wrote:<br>
> Hi All,<br>
><br>
> I want to know "What is a console?<br>
<br>
</div>A console is where the output from printk goes.<br>
<div class="im"><br>
> and Why it is always associated with<br>
> UART?"<br></div></blockquote><div><br></div><div><br></div><div>Yes, console is output and UART is the hardware device input port.....it can be implemented hardware wise by many different devices, but all of them will speak the UART protocol:</div>
<div><br></div><div><meta http-equiv="content-type" content="text/html; charset=utf-8"><a href="http://en.wikipedia.org/wiki/Universal_asynchronous_receiver/transmitter">http://en.wikipedia.org/wiki/Universal_asynchronous_receiver/transmitter</a></div>
<div><br></div><div>and the hardware devices' source codes are in drivers/tty/serial/8250_xxxxx.c for examples (xxxx for different devices).</div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">
<br>
</div>While console's may often be associated with a UART (typical for<br>
embedded systems) there is no need or requirement for them to be<br>
associated with a console. You can regitser a console to send the<br>
output wherever you like.<br>
<div class="im"><br>
> What is a serial console??<br>
<br>
</div>A serial console is a console driver (registered via register_console)<br>
which sends the output to a serial port, typically also allowing the<br>
serial port to be used as a tty interface.<br>
<div class="im"><br>
> Can there be a USB console??<br>
<br>
</div>Sure. I don't know if a driver for this exists yet, but if it doesn't<br>
you can always write one.<br>
<br></blockquote><div><br></div><div>According to the diagram of the book "Essential Linux Device Drivers" page 175, both the output of serial_core.c and usb-serial.c (which implements the serial signals coming in from the USB interface) are directed to n_tty.c (which essentially goes to the serial console output). So answer is NO, current architecture has the tty console linked to both UART and USB-Serial interface. (a FTDI software driver drivers/usb/serial/ftdi_sio.c is needed to convert the USB signal back to the serial packets structure). </div>
<div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
There is already something called a netconsole (see<br>
Documentation/networking/netconsole.txt). This is an example of a<br>
console which isn't associated with a serial port.<br>
<br>
There is also a framebuffer console (See Documentation/fb/fbcon.txt)<br>
<font color="#888888"><br>
--<br>
Dave Hylands<br>
Shuswap, BC, Canada<br>
<a href="http://www.davehylands.com" target="_blank">http://www.davehylands.com</a><br>
<br>
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</font></blockquote></div><div><br></div>Happy Hacking.....<br><br clear="all"><div><br></div>-- <br>Regards,<br>Peter Teoh<br>
</div>