Hope I can contribute and sorry for the interruption of conversation :-(.
On Tue, Jan 10, 2012 at 2:59 PM, Dave Hylands
<dhylands@gmail.com> wrote:
Hi sandeep,
On Mon, Jan 9, 2012 at 10:37 PM, sandeep kumar
<
coolsandyforyou@gmail.com> wrote:
> Hi All,
>
> I want to know "What is a console?
> and Why it is always associated with
> UART?"
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:
and the hardware devices' source codes are in drivers/tty/serial/8250_xxxxx.c for examples (xxxx for different devices).
While console's may often be associated with a UART (typical for
embedded systems) there is no need or requirement for them to be
associated with a console. You can regitser a console to send the
output wherever you like.
> What is a serial console??
A serial console is a console driver (registered via register_console)
which sends the output to a serial port, typically also allowing the
serial port to be used as a tty interface.
> Can there be a USB console??
Sure. I don't know if a driver for this exists yet, but if it doesn't
you can always write one.
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).
There is already something called a netconsole (see
Documentation/networking/netconsole.txt). This is an example of a
console which isn't associated with a serial port.
There is also a framebuffer console (See Documentation/fb/fbcon.txt)
--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
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