What are the differences bettween rtdm_open function and open function used to get the file handle of the rtdm driver?

Jan Kiszka jan.kiszka at siemens.com
Tue Apr 14 11:00:55 CEST 2020


On 14.04.20 10:55, 孙世龙 via Xenomai wrote:
> Hi,
>         The rtdm_open function is described as inter-driver interface.
>         What are the differences between rtdm_open function and open
> function used to get the file handle of the rtdm driver.
>         I have searched all the source code of xenomai-3.1.I found no usage
> of this function.

The usage of this function is rare, maybe even zero out there. The idea 
behind it is to allow driver stacking: One or more RTDM drivers provides 
lower-level interfaces, e.g. to get a UART device, another one uses that 
to provide a higher-level protocol on top that cannot or should not be 
implemented in user-space. However, the latter is often not an issue, so 
you find no users of this stacking pattern in-tree. If you don't see a 
case yet for yourself, ignore the API.

Jan

-- 
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux



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