From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Franz Engel" <franz_lambert_engel@yahoo.de>
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	<51C45C6F.9080109@siemens.com>
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Date: Sat, 22 Jun 2013 13:57:26 +0200
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Subject: Re: [Xenomai] High latency and smi with intel vendor chip
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To: 'Jan Kiszka' <jan.kiszka@siemens.com>
Cc: xenomai@xenomai.org

Franz Engel wrote:
> Jan Kiszkas wrote:
> > Franz Engel wrote:
> > Hi,
> >
> > In my dmesg I get the following message:
> > dmesg | grep -i xeno
> > [    4.478964] I-pipe: head domain Xenomai registered.
> > [    4.494089] Xenomai: hal/x86_64 started.
> > [    4.505969] Xenomai: scheduling class idle registered.
> > [    4.521300] Xenomai: scheduling class rt registered.
> > [    4.538525] Xenomai: real-time nucleus v2.6.2.1 (Day At The Beach)
> loaded.
> > [    4.559065] Xenomai: debug mode enabled.
> > [    4.579351] Xenomai: SMI-enabled chipset found
> > [    4.592628] Xenomai: SMI workaround failed!
> > [    4.605677] Xenomai: starting native API services.
> > [    4.619979] Xenomai: starting POSIX services.
> > [    4.633088] Xenomai: starting RTDM services.
> >
> >
> > And I have very high latencies. I read that I should try to insert my
> the ID of my LCP into the /usr/src/xenomai/ksrc/arch/x86/smi.c file.
> 
> That is no longer true since 2.6.2.1. Xenomai already detects your LPC
> (see above), but the BIOS has apparently locked SMI disabling down.
> 
> In this case, you may want to play with smi_mask (see documentation of
> "SMI_EN - SMI Control and Enable Register" in the Intel chipset
> manuals) to see if disabling of individual SMI features work. If not,
> the board is useless for low-latency real-time purposes.

I found the documentation for my chipset. But I'm not sure with the
interpretation. I think that chapter 13.8.3.11 "SMI_EN-SMI Control and
Enable Register"
(http://www.intel.com/content/dam/doc/datasheet/io-controller-hub-10-family-
datasheet.pdf) is the chapter that descript the options for SMI. But I don't
know how to interpret it. It would be very nice if somebody could look into
and say me how to understand it and how I can use this information to reduce
my latency (if possible).
> 
> Jan
Franz