Re: [Xenomai-help] New install of Xenomai 2.3 for 2.6.17 kernel.... Various problems

[Philippe Gerum <rpm@xenomai.org>]

On Fri, 2007-03-23 at 14:47 +0000, xenomai@domain.hid wrote:
> I removed the offending modules that were hanging modprobe but am now seeing hald doing the same thing.  I'll try making it as a module and loading after bootup.
> 

Btw, make sure 100% that all your modules issued from the kernel
compilation in question have been properly installed under /lib/modules.

Additionally, it has been reported (and I recently experienced this
myself) than under some specific circumstances, only running a "make
clean" in an old Xenomai-enabled kernel tree before upgrading the
Xenomai support with prepare-kernel.sh, then compiling anew, is _not_
enough. This may introduce some funky issues, likely due to missed
dependencies in the kernel tree.

E.g.

$ cd .../linux-xeno-2.2.5 && make clean
$ ~/xenomai-2.3.1/scripts/prepare-kernel.sh --forcelink --arch=x86
--linux=.
$ [ make oldconfig && ] make

The above may _NOT_ always work as expected.

The best way to prevent this is to compile a freshly patched kernel,
only recycling the .config file from the old kernel, which is definitely
ok (make mrproper in the old kernel would likely work too).

> Mike
>  -------------- Original message ----------------------
> From: Philippe Gerum <rpm@xenomai.org>
> > On Fri, 2007-03-23 at 14:04 +0000, xenomai@domain.hid wrote:
> > > Hello,
> > > 
> > > I have been working on trying to find the optimal linux kernel configuration 
> > and have noticed a couple problems.
> > > No matter what I do it seems that while cpu #2 is detected, nothing gets 
> > scheduled on it. 
> > 
> > If not already done, try building the Xenomai nucleus as a module
> > instead of statically into the kernel. Is the situation normal with
> > respect to load balancing between CPUs before you eventually modprobe
> > this module?
> > 
> > > Also, there is always a modprobe process running at 100%cpu that I can't kill.
> > 
> > modprobe of which module?
> > 
> > >   The command that is showed in top is "modprobe -s ac".  If I run it from the 
> > command line it hangs as well.
> > >   Latencies are however very acceptable when running xeno-test.  I do however 
> > see some negative values
> > >  in the test output.
> > 
> > Negative values are (mostly) ok. This only means that your machine is
> > faster than pre-calibrated for, which causes the timer shots to be ahead
> > of time, due to a pessimistic calibration.
> > Check /proc/xenomai/latency, this gives the intrinsic latency Xenomai
> > anticipates when programming timer shots (i.e. interrupt latency +
> > scheduling latency altogether), given as a count of nanoseconds.
> > 
> > You can change this value on the fly while the latency test is running;
> > just echo a new value to this file. You should try lowering it until all
> > the values (particularly the leftmost ones, i.e. "min lat") raise
> > slightly above zero.
> > 
> > > 
> > > The config file that I am using currently is the same as the one below just 
> > with CONFIG_XENO_HW_SMI_ALL.
> > >   This seems to give me the best latencies.
> > > 
> > > Mike
> > > 
> > >  -------------- Original message ----------------------
> > > From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
> > > > xenomai@domain.hid wrote:
> > > > >  -------------- Original message ----------------------
> > > > > From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
> > > > > 
> > > > >>xenomai@domain.hid wrote:
> > > > >>
> > > > >>>#
> > > > >>># SMI workaround
> > > > >>>#
> > > > >>># CONFIG_XENO_HW_SMI_DETECT_DISABLE is not set
> > > > >>>CONFIG_XENO_HW_SMI_DETECT=y
> > > > >>>CONFIG_XENO_HW_SMI_WORKAROUND=y
> > > > >>># CONFIG_XENO_HW_SMI_ALL is not set
> > > > >>># CONFIG_XENO_HW_SMI_INTEL_USB2 is not set
> > > > >>># CONFIG_XENO_HW_SMI_LEGACY_USB2 is not set
> > > > >>># CONFIG_XENO_HW_SMI_PERIODIC is not set
> > > > >>># CONFIG_XENO_HW_SMI_TCO is not set
> > > > >>># CONFIG_XENO_HW_SMI_MC is not set
> > > > >>>CONFIG_XENO_HW_SMI_APMC=y
> > > > >>># CONFIG_XENO_HW_SMI_LEGACY_USB is not set
> > > > >>>CONFIG_XENO_HW_SMI_BIOS=y
> > > > >>
> > > > >>Chances are that the latencies you get are due to the SMI you leave
> > > > >>enabled (APMC or BIOS). Could you try first with only
> > > > >>CONFIG_XENO_HW_SMI_ALL ?
> > > > >>
> > > > > WOW!!!  I did try that with the 2.6.17 kernel but it wouldnt boot,
> > > > > I had to enable APM.  It is working like  charm now.  Max latency
> > > > > is 4-5 us while running X.  If I drag a window around it goes up
> > > > > to 7us or so.  Deffinately a step in the righ direction!  Thanks.
> > > > 
> > > > Good news.
> > > > 
> > > > -- 
> > > >                                                  Gilles Chanteperdrix
> > > 
> > > 
> > > _______________________________________________
> > > Xenomai-help mailing list
> > > Xenomai-help@domain.hid
> > > https://mail.gna.org/listinfo/xenomai-help
> > -- 
> > Philippe.
> > 
> > 
> 
-- 
Philippe.