Comment 4 for bug 595018

Bryan,

My apologies- this problem is now resolved but it was one of so many problems
that I forgot to close it. The details that follow are a bit vague because
the system is now packed for transit and I can't read any of the details.

The issue was the sources for the particular kernel (I can't remember exactly
2.6.33-something) I was using appeared not to be available and the staging
drivers were not in the kernel package.

I believe that part of the problem was that the comedi drivers went in and out
of the ubuntu kernel in .33 and eventually moved to staging.

I got 2.6.34 from somewhere and performed a native build on the beagleboard.
The comedi packages _do not_ compile for the beagleboard because of a
architecture dependent flag in drivers.cc. With a small and naive (but most
likely harmless) hack I got the drivers to compile and with my new kernel the
comedi drivers are now working. The matter is live on the comedi list but no
one is sure how to implement that required change - doing it "properly" is
likely to be a huge change with knock on effects, my lightweight fix is
unlikely to be accepted into the kernel.

Fortunately anything my hack could nobble lies in drivers that cannot run on
the beagleboard (because it lacks the hardware) so I am pretty sure it is
safe for anything the the beagleboard can run.

The hack, for reference, is to change the single instance
of "PAGE_KERNEL_NO_CACHE" to "PAGE_KERNEL" in the comedi drivers.c. The
NO_CACHE variant of the page protection flag is not defined for OMAP (or
several other processor) but is required for one particular PCI card on
x86. "PAGE_KERNEL" has sufficient protection for the USBDUX etc drivers.

It would be nice if ubuntu had the tool chain packaged up so that cross
compiling could be done without using OE. Frequently the various instructions
I found were rather vague. A simple script for installing the kernel and
setting up uboot would alos be nice as it is hard to remember all the magic
settings required.

I think it is safe to close this bug - sorry I forgot to do this earlier.

Cheers,

SA

On Thursday 24 June 2010 08:15:50 Bryan Wu wrote:
> @SA,
>
> Could you please tell us how did you compile the comedi drvers as
> modules? Normally, we cloned Lucid kernel tree here,
> git://kernel.ubuntu.com/ubuntu/ubuntu-lucid.git. And ti-omap branch is
> the kernel for omap3 based machine.
>
> Apparently, comedi drivers are there drivers/staging/comedi. If you have
> problem to compile it, please post the error message here.
>
> -Bryan
>
> ** Changed in: linux-ti-omap (Ubuntu)
> Status: New => Incomplete
>
> ** Changed in: linux-ti-omap (Ubuntu)
> Importance: Undecided => Low
>
> ** Changed in: linux-ti-omap (Ubuntu)
> Assignee: (unassigned) => Bryan Wu (cooloney)