[Xenomai-core] tasklet using Xenomai

[Xenomai-core] tasklet using Xenomai

[Anisha Kaul]

Dear all,

How to define a tasklet using Xenomai for a serial port interrupt handler? 
Does 'rtdm_event_init()' function work as a tasklet in Xenomai ?

Thanking you in anticipation,
Anisha Kaul

-------------------------------------
Hi-Tech Gears Limited, Gurgaon, India

Re: [Xenomai-core] tasklet using Xenomai

[Jan Kiszka]

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Anisha Kaul wrote:
> Dear all,
> 
> How to define a tasklet using Xenomai for a serial port interrupt handler? 
> Does 'rtdm_event_init()' function work as a tasklet in Xenomai ?

An RTDM event is a binary semaphore for use inside a kernel driver -
probably not what you are looking for. What should be the semantic of
this tasklet, that of old RTAI? And what is the use case behind it?

Jan


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Re: [Xenomai-help] tasklet using Xenomai

[Jan Kiszka]

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[ Please don't drop CCs! ]

Anisha Kaul wrote:
>> Anisha Kaul wrote:
>>> Dear all,
>>>
>>> How to define a tasklet using Xenomai for a serial port interrupt
>>> handler? Does 'rtdm_event_init()' function work as a tasklet in Xenomai ?
>> An RTDM event is a binary semaphore for use inside a kernel driver -
>> probably not what you are looking for. What should be the semantic of
>> this tasklet, that of old RTAI? And what is the use case behind it?
>>
>> Jan
> 
> Thanks for the prompt reply ! 
> 
> The tasklet I am talking about is supposed to re-set the registers of the 
> serial port each time an interrupt occurs ! We can do this the following way 
> in using Linux system calls :
> 
> void resetRegisters (unsigned long currentlyUnused);
> 
> DECLARE_TASKLET  (rs232Tasklet, resetRegisters, 0);
> 
> void resetRegisters (unsigned long currentlyUnused)
> {
>         outb (0x83, PORT + 3);
>         outb (0x01, PORT + 0);
>         outb (0x00, PORT + 1);
>         outb (0x03, PORT + 3);
>         outb (0x01, PORT + 1);
>         outb (0x63, PORT + 2);
>         outb (0x08, PORT + 4);
> }

This looks like a weird use of tasklets under mainline. Moreover, they
are practically deprecated there.

> 
> How am I supposed to do this using Xenomai ?
> 

Have you considered simply using the rt_16550A driver for your purpose?
You didn't told us your use case from an application POV, so it's hard
to say if the driver meets your requirements. But it does not require
you fiddling with hardware directly.

Jan


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Re: [Xenomai-core] tasklet using Xenomai

[Anisha Kaul]

> > Thanks for the prompt reply !
> >
> > The tasklet I am talking about is supposed to re-set the registers of the
> > serial port each time an interrupt occurs ! We can do this the following
> > way in using Linux system calls :
> >
> > void resetRegisters (unsigned long currentlyUnused);
> >
> > DECLARE_TASKLET  (rs232Tasklet, resetRegisters, 0);
> >
> > void resetRegisters (unsigned long currentlyUnused)
> > {
> >         outb (0x83, PORT + 3);
> >         outb (0x01, PORT + 0);
> >         outb (0x00, PORT + 1);
> >         outb (0x03, PORT + 3);
> >         outb (0x01, PORT + 1);
> >         outb (0x63, PORT + 2);
> >         outb (0x08, PORT + 4);
> > }
>
> This looks like a weird use of tasklets under mainline. Moreover, they
> are practically deprecated there.
>
> > How am I supposed to do this using Xenomai ?
>
> Have you considered simply using the rt_16550A driver for your purpose?
> You didn't told us your use case from an application POV, so it's hard
> to say if the driver meets your requirements. But it does not require
> you fiddling with hardware directly.
>
> Jan


" This looks like a weird use of tasklets under mainline. Moreover, they are 
practically deprecated there."

Why do you say this ?

" Have you considered simply using the rt_16550A driver for your purpose? "

I was not aware that a serial port driver for real time does exist ! 
Secondly, here we are writing a robotic application where we want to stop the 
robot if we receive data 'x' or move the robot if we receive data 'y'. 
Can you tell me how can we achieve this functionality with rt_16550A driver.
Is rt_16550A driver fully stable ?

thanks,
anisha

-------------------------------------
Hi-Tech Gears Limited, Gurgaon, India

Re: [Xenomai-core] tasklet using Xenomai

[Jan Kiszka]

Anisha Kaul wrote:
>>> Thanks for the prompt reply !
>>>
>>> The tasklet I am talking about is supposed to re-set the registers of the
>>> serial port each time an interrupt occurs ! We can do this the following
>>> way in using Linux system calls :
>>>
>>> void resetRegisters (unsigned long currentlyUnused);
>>>
>>> DECLARE_TASKLET  (rs232Tasklet, resetRegisters, 0);
>>>
>>> void resetRegisters (unsigned long currentlyUnused)
>>> {
>>>         outb (0x83, PORT + 3);
>>>         outb (0x01, PORT + 0);
>>>         outb (0x00, PORT + 1);
>>>         outb (0x03, PORT + 3);
>>>         outb (0x01, PORT + 1);
>>>         outb (0x63, PORT + 2);
>>>         outb (0x08, PORT + 4);
>>> }
>> This looks like a weird use of tasklets under mainline. Moreover, they
>> are practically deprecated there.
>>
>>> How am I supposed to do this using Xenomai ?
>> Have you considered simply using the rt_16550A driver for your purpose?
>> You didn't told us your use case from an application POV, so it's hard
>> to say if the driver meets your requirements. But it does not require
>> you fiddling with hardware directly.
>>
>> Jan
> 
> 
> " This looks like a weird use of tasklets under mainline. Moreover, they are 
> practically deprecated there."
> 
> Why do you say this ?

The function you defer from interrupt context into a tasklet is
comparably cheap, specifically on modern systems. So the management
overhead is expect to be in the same dimension as the workload (you do
not gain noticeably shorter IRQ-off times this way).

> 
> " Have you considered simply using the rt_16550A driver for your purpose? "
> 
> I was not aware that a serial port driver for real time does exist ! 
> Secondly, here we are writing a robotic application where we want to stop the 
> robot if we receive data 'x' or move the robot if we receive data 'y'. 
> Can you tell me how can we achieve this functionality with rt_16550A driver.

Check existing examples and the RTDM serial profile documentation.

> Is rt_16550A driver fully stable ?

Yes, it's used, among other things, in robotics for many years.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux

[Xenomai-core] switches between hard real time and soft real time

[Anisha Kaul]

hi,

Is there any command or technique to know when your kernel module is running 
on hard-real time and when it switches to soft-real time (because of any 
linux system call) ?

thanks,
anisha

-------------------------------------
Hi-Tech Gears Limited, Gurgaon, India

Re: [Xenomai-core] switches between hard real time and soft real time

[Gilles Chanteperdrix]

Anisha Kaul wrote:
> hi,

Hi,

Please do not reply to an unrelated mail when asking a new question.
Mail clients which do proper threading, such as the mailing list
archives will show it in the same thread as the mail you reply to.

> 
> Is there any command or technique to know when your kernel module is running 
> on hard-real time and when it switches to soft-real time (because of any 
> linux system call) ?

Please read:
http://www.xenomai.org/documentation/branches/v2.3.x/pdf/Life-with-Adeos-rev-B.pdf
http://www.xenomai.org/documentation/branches/v2.3.x/pdf/Native-API-Tour-rev-C.pdf

-- 
                                          Gilles

Re: [Xenomai-help] [Xenomai-core] switches between hard real time and soft real time

[Philippe Gerum]

On Tue, 2009-11-10 at 18:20 +0530, Anisha Kaul wrote:
> hi,
> 
> Is there any command or technique to know when your kernel module is running 
> on hard-real time and when it switches to soft-real time (because of any 
> linux system call) ?

Off-topic on this list. Please switch to xenomai-help.

> 
> thanks,
> anisha
> 
> -------------------------------------
> Hi-Tech Gears Limited, Gurgaon, India
> 
> 
> 
> 
> 
> _______________________________________________
> Xenomai-core mailing list
> Xenomai-core@domain.hid
> https://mail.gna.org/listinfo/xenomai-core


-- 
Philippe.