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Top Forums Programming Aplication user and kernel mode (data access) Post 302119066 by Brendan Kennedy on Sunday 27th of May 2007 09:44:40 AM
Old 05-27-2007
Aplication user and kernel mode (data access)

Hi all,

I am trying to setup a program to use a device driver and am confusing buffer access between User and Kernel mode. I think all applications running in User space have to communicate with the device drivers using io control calls and then have some functions called back from the driver app.

In this model, I guess the User app passes buffer pointer values to the driver
using the ioctl calls. Is that what happens? For example, I have a session
context struct created by the user app using malloc. Would that data have to
be copied to the driver for it to be used, or could I just pass a pointer to
the struct?

Is using ioctl calls the only way to 'switch to kernel mode'??
Also, am I right in saying the process running on the device driver is
separate from the one running in the application? how does that work in
relation to a threaded application? must a new thread be created with each
function call back?

You can probably tell I am very confused here, so any help is greatly
apreciated!

Regards,
Brendan
 

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MODE2(1)							   User Commands							  MODE2(1)

NAME
mode2, smode2, xmode2 - shows the pulse/space length of infrared signals SYNOPSIS
xmode2 [options] DESCRIPTION
The main purpose of these programs is to check operation of your home-brew LIRC receiver hardware and to see the IR waveform of the remote controller without an expensive oscilloscope. Very useful for debugging. Of course this program won't work with hardware that decodes the signals itself like e.g. TV cards or the Irman. xmode2 is based on smode2 by Sinkovics Zoltan. It is just a conversion from svga to X with some basic support for resizing. The only dif- ferences are that the --mode option enables an alternative display mode and that xmode2 can read and visualise mode2 output from stdin. -h --help display usage summary -v --version display version -d --device=device read from given device -H --driver=driver use given driver -g --geometry=geometry window geometry -t --timediv=value ms per unit -m --mode enable alternative display mode -r --raw access device directly SEE ALSO
mode2(1), smode2(1), xmode2(1) The documentation for lirc is maintained as html pages. They are located under html/ in the documentation directory. mode2 0.9.0-pre1 October 2010 MODE2(1)
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