RT Patch

Hello,

Has somebody expirience running kernel with RT patch? And if yes which
version of kernel? Can I patch kernel fro friendlyarm download section.
Thanks a lot.

Good luck with that. I patched lots of mini2440 kernels with RT and XEnomai
patches. However, all of them failed to boot properly despite the fact they
all compiled correctly. 

Buy a different board featuring a different processor (Atmel has excellent
support for high resolution timers and Xenomai framework).

Whatever you do with this board, don't bother patching it with realtime.
Again, you'll waste your time.

I have running compilation of 2.6.29-rt17 but there is no support of
hr-timers. Any idea or patch for high_res_timers for this board ?

I'm working on Xenomai on this board right now. The kernel boots but
Xenomai don't work right now. Going to fix it.

I also try to get HR timers support to mini2440 but as mini2440_enthus
states it fails to boot despite it is build correctly. IMO s3c2440 doesn't
have any timer which could be user for HR that is blocking point. Or?

marek

It failed before, yes. I managed to debug this problem via JTAG and
contacted Adeos I-Pipe / Xenomai developers. They submitted some patches
and now I'm able to run I-pipe patched kernel.

Please follow this thread:
http://www.mail-archive.com/adeos-main@gna.org/msg01729.html

Now I still have problems (the kernel works but hangs after "modprobe
xeno_native"), but I believe I know why and how to fix them. Stay tuned.

MINI2440's hardware and ecpecially timers seem to be Ok. All the problems
are due to lack of support and stable software, not exactly
hardware-related. It may turn into a best realtime board if there are
enough skilled enthusiasts to debug, test, JTAG'em and so on.

Linux kernel uses TIMER4 for its interrupt-based time tracking. It is
however not enough for realtime job, so Xenomai uses two timers. TIMER4
does the interrupt ("ticks") job while TIMER3 is free-running at high speed
(12 MHz I believe) and is used to measure sub-tick intervals. This seems to
be good enough. However, TIMER3 should not be used for any other
peripherals (I suggest turning "PWM Support" in Kconfig off) or at least
not reprogrammed; one may still use its output for fixed-frequency clock or
even PWM if its input frequency and counters are untouched.

Latest Xenomai seems to work fine on mini2440 using 2.6.35.9 linux kernel.
You'll need the SVN version of ipipe and xenomai (or patch the tarball one
with patches from ipipe mailing list). Also you'll need two patches from
LKML to get GPIO and touchscreen working.

That's what I'm say ;) : http://friendlyarm.net/forum/topic/1165#12601

I use Titan board from Eurotech with linux-2.6.20.18 patched by 2.6.20-rt8.
Unfortunately, the hrtimer is not available, detected by cyclictest even
that the kernel can be compiled and booted correctly.