Re: [Xenomai-help] LATENCIES > 100 us or CRASH WITH X (with joints pieces)

[Jan Kiszka <jan.kiszka@domain.hid>]

[-- Attachment #1: Type: text/plain, Size: 1895 bytes --]

Jean-Luc Pamart wrote:
> Hello
> 
> I am a newbie with Xeno. My goal for the beginning of 2007 is to launch
> a project for 4 french studiants : a box with Linux embedded and a usb
> camera. The embedded application will analyse the movies in Real time
> and lead a mobile machine with CAN-BUS.
> Now i play with Xeno for my knowledge (without specific hardware) :  a
> little linux installed in a usb key with a little embedded distrib
> 
> - vanilla kernel 2.6.16 with patch for usb [.config is joint]
> - Xenomai 2.1.2
> - essentially BusyBox
> - for xenomai : only "latency" directory and libs in usr/libs
> I have checked "SMI woraround" for the kernel.
> In BIOS I have UNchecked  "legacy usb".
> 
> 
> my Desktop PC (a AMD ATHLON) can boot with this little vanilla kernel and
> 1/ a little embedded distrib of my own
> 
> OR
> 
> 2/ a complete mandrake 9.1 on a partition of a classic hard disk
> 
> I have 2 differents problems when I lauch this :
> 
> 1/ with the linux embedded directories on the usb key
> high latency > 100 us are ok ? perhaps usb work is not compatible with RT ?

Try loading the standard USB drivers (at least uhci_hcd) if they aren't
yet. Actually, I've seen boxes (granted, they were far older) where I
had to switch legacy USB *on* to avoid disturbances. In any case, check
carefully if you followed all tips in TROUBLESHOOTING regarding latency
issues (APM, ACPI, etc.).

> 
> 
> 2/ with the complete mandrake 9.1 :
> it crashes X after 1 or few minutes.
> What is the relation between X and Xenomai ?
> Is Xenomai compatible with X ?

Yes, as long as X is not playing against us, e.g. by hard-disabling
interrupts or doing (too) evil things on the buses. Any non-GPL driver
in this game here (NVidia&Co)? Better avoid this. Also try to disable
accelerated mode in your X setup to see if things improve.

Jan


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 250 bytes --]