On Wed, May 10, 2000 at 06:35:00PM -0400, Rich Bryant wrote:
> The fact that the drivers support multiple devices also makes it hard
> to know what I need and what I don't. The goal of my whole project is to
> create a version of Linux(preferebly Real Time) for an embedded board. The
See Nicholas McGuire's MiniRTLinux on www.fsmlabs.com. It fits on a
floppy and runs in 4Meg. It may not be exactly what
you want, but it is a good starting point. Nicholas did some smart
work minimizing kernel memory usage and then also uses the wonderful
busybox.
> board is for educational use and the way the Kernel is organized is very
> forbidding to someone who only wants to look at specific areas and
> understand them. The fact that the board has limited hardware makes it an
> even greater challenge. I have no need for the majority of the drivers and
> in many cases large portions of the drivers I do need.
>
> I do have the specification for the 16550, understanding the hardware isn't
> any where near as confusing as tryign to figure out what I can safely
> eliminate from the driver and what is used by other functions within it. I
> don't mind spending a couple weeks to understand the driver, but I find
> myself digging through files for something that could have been stated in a
> 3 word comment.
>
> I do notice that the comments have gotten better with newer versions of
> Kernel, but there is also more complexity with the addition of new things
> to the Kernel. Has there been any thought given to other ways of
> supporting devices rather than numberous #ifndef statements?
>
> Forgive me for ranting,
>
> Rich
>
>
> Wed, 10 May 2000, Theodore Y. Ts'o wrote:
>
> >
> > Steve pretty much covered most of responses I would have given, so I'll
> > limit myself to pointing out a couple of other resources.
> >
> > 1) If you're trying to write Linux device driver for a non-16550
> > device, check out the definitions in include/linux/tty_driver.h and
> > include/linux/tty_ldisc.h. That documents most of the Linux tty
> > interfaces, at least at a basic level.
> >
> > 2) If you're trying to figure out how to program a 16550 UART for the
> > purposes of creating a device driver for another OS, I suggest you get a
> > copy of the National Semincoductor Application Notes for the 16550 UART.
> > They have some very nicely documented code which shows how to access the
> > UART. Another good reference guide is the book "Programmer's Technical
> > Reference: Data and Fax Communications", by Robert L. Hummet, which has
> > a good section on explaining UART programming.
> >
> > - Ted
> >
>
>
>
>
> -
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