[Xenomai-help] request_region from rtdm_task

[Xenomai-help] request_region from rtdm_task

[Maciek Godek]

Hi,

is it OK to call function request_region from kernel rtdm task?

or, should there be any problems when using io ports in rtdm task from
range requested in non-rt kernel thread?

thanks in advance
maciek

Re: [Xenomai-help] request_region from rtdm_task

[Jan Kiszka]

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Maciek Godek wrote:
> Hi,
> 
> is it OK to call function request_region from kernel rtdm task?

Generally, you have to review each Linux service you call from RT
context /wrt determinism and locking issues. And often this analysis is
kernel release-dependent. So, better avoid this. This is even more
unneeded when service like this one aim at the driver initialisation,
not at its operation mode.

> 
> or, should there be any problems when using io ports in rtdm task from
> range requested in non-rt kernel thread?

request_region does not track the calling process implicitly. All it
saves is the arbitrary name you passed. So, yes, you can call it safely
during the usual, non-RT driver initialisation and simply use the ports
later on in RT context. You could even play roulette and skin
request_region, but that would be error-prone or at least bad style (for
any kind of Linux driver).

Jan


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