[ag-automation] [ANNOUNCE] RTDM for Linux-rt

[Jan Kiszka]

Hi Carsten,

[adding xenomai to cc again]

Carsten Emde wrote:
> Wolfgang,
> 
>> Attached you can find a README on how to install and use RTDM-native and
>> the current implementation status.
> I couldn't stop my curiosity to see it working. So, I downloaded the 
> material from the repository and attacked linux-2.6.21-rc6-rt0 after 
> enabling everything available in the "Real-time subsystem". BTW: 
> Wouldn't it be less confusing to call this section differently? For 
> example "RTDM subsystem" or similar? Sorry, just a first thought - there 
> is so much real-time everywhere.

Yes, I think so as well. The menu naming comes from the history of the
build system (Xenomai).

> 
> I then tried to build a new kernel. With a single exception, everything 
> compiled without warning. The exception was switchtest that refused to 
> build:
> 
> drivers/xenomai/testing/switchtest.c:1:27: error: nucleus/synch.h: No 
> such file or directory
> drivers/xenomai/testing/switchtest.c:2:28: error: nucleus/thread.h: No 
> such file or directory
> drivers/xenomai/testing/switchtest.c:5:32: error: asm/xenomai/fptest.h: 
> No such file or directory

That driver shouldn't be part of rtdm-native, it's for stress-testing
the Xenomai nucleus.

> 
> After disabling it, all sources could be compiled without any further 
> problem. Linking xeno_rtdmtest.ko and xeno_16550A.ko, however, failed:
> WARNING: "hrtimer_init_sleeper" 
> [drivers/xenomai/testing/xeno_rtdmtest.ko] undefined!
> WARNING: "hrtimer_init_sleeper" [drivers/xenomai/serial/xeno_16550A.ko] 
> undefined!

At least in 2.6.20, hrtimer_init_sleeper() is not exported to modules.
Hmm, maybe Wolfgang tested both as built-in components, but that would
just be a workaround.

> 
> I then disabled these two modules as well. The rest could be compiled 
> and linked smoothly. The kernel was able to boot and the modules 
> xeno_irqbench and xeno_can_virt could be loaded normally.
> 
> I then tried linux-2.6.20-rt8 - same situation as described above.
> 
> Will do some testing later. Anybody out there who would like to join the 
> RTDM-Native Testing Group?

Would love to, but short on time...

You may want to start by playing with irqbench [1] (IRQ latency tests
across nullmodem or laplink cable) or with the CAN stack, for which
xeno_can_virt offers you a virtual local bus of two CAN interfaces [2].

Jan

[1]http://www.rts.uni-hannover.de/xenomai/lxr/source/doc/txt/irqbench.txt
[2]http://www.rts.uni-hannover.de/xenomai/lxr/source/src/utils/can/README

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