problems with realtime kernel on Beaglebone AI

[John Allwine]

I posted this on the Beaglebone forums and figured someone here may be able to help too:

I'm trying to use a real time kernel on the Beaglebone AI to get MachineKit running. I'm able to run MachineKit on a non-rt kernel (4.14.108-ti-r113), but when I update to the latest ti-rt kernel (4.14.108-ti-rt-r134), I get an error: 

user cannot gain I/O privileges - forgot 'sudo make setuid'?

In dmesg, I see this:

[  811.654246] warning: process `rtapi:0' used the deprecated sysctl system call with 8.1.2.

Robert Nelson offered to tweak the rt kernel config to support that call. Is that what needs to happen?

[John Allwine]

This seems to be the source of the problem: https://github.com/machinekit/machinekit-hal/blob/9fca994e08e3f8384498e78ea8e8baa1c899e4db/src/rtapi/rtapi_app.cc#L1457

The system call iopl seems to be returning an error:

http://man7.org/linux/man-pages/man2/iopl.2.html

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[ce...@tuta.io]

Hi,
May 1, 2020, 23:36 by jo...@pocketnc.com:

> This seems to be the source of the problem: > https://github.com/machinekit/machinekit-hal/blob/9fca994e08e3f8384498e78ea8e8baa1c899e4db/src/rtapi/rtapi_app.cc#L1457
>

You are not the only one bitten. There is/was discussion in Machinekit Matrix room, history: https://view.matrix.org/room/!CLLXbpAoUbAfHmWDXt:matrix.org/?anchor=$158837589690473CEniQ:matrix.org&offset=0

Personally, I consider it premature and think that the program should cross that bridge when it comes at it and not when everything it sees is flat land. So I would remove it.

Cern.

>
> The system call iopl seems to be returning an error:
> http://man7.org/linux/man-pages/man2/iopl.2.html
>
> On Fri, May 1, 2020 at 2:49 PM John Allwine <> jo...@pocketnc.com> > wrote:
>

>> I posted this on the >> Beaglebone forums <https://groups.google.com/forum/#!category-topic/beagleboard/FOEDBLvmu2c>>> and figured someone here may be able to help too:

>>
>> I'm trying to use a real time kernel on the Beaglebone AI to get MachineKit running. I'm able to run MachineKit on a non-rt kernel (4.14.108-ti-r113), but when I update to the latest ti-rt kernel (4.14.108-ti-rt-r134), I get an error: 
>>
>> user cannot gain I/O privileges - forgot 'sudo make setuid'?
>>
>> In dmesg, I see this:
>> [  811.654246] warning: process `rtapi:0' used the deprecated sysctl system call with 8.1.2.
>>
>> Robert Nelson offered to tweak the rt kernel config to support that call. Is that what needs to happen?
>>
>>
>>
>> --
>> website: >> http://www.machinekit.io>> blog: >> http://blog.machinekit.io>> github: >> https://github.com/machinekit
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>> You received this message because you are subscribed to a topic in the Google Groups "Machinekit" group.
>> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/machinekit/1iYGU9VfvPM/unsubscribe>> .
>> To unsubscribe from this group and all its topics, send an email to >> machinekit+...@googlegroups.com>> .

>> To view this discussion on the web visit >> https://groups.google.com/d/msgid/machinekit/5221d20d-643b-4a7a-bab6-42a2886b59c9%40googlegroups.com <https://groups.google.com/d/msgid/machinekit/5221d20d-643b-4a7a-bab6-42a2886b59c9%40googlegroups.com?utm_medium=email&utm_source=footer>>> .

>>
>
>
>
> --
> website: > http://www.machinekit.io> blog: > http://blog.machinekit.io> github: > https://github.com/machinekit
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> You received this message because you are subscribed to the Google Groups "Machinekit" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to > machinekit+...@googlegroups.com> .
> To view this discussion on the web visit > https://groups.google.com/d/msgid/machinekit/CAPEK9qbEdq5hL4p5yNsWa6DSTthhed-vM7CBdSBX%3DFPHMZ0BBg%40mail.gmail.com <https://groups.google.com/d/msgid/machinekit/CAPEK9qbEdq5hL4p5yNsWa6DSTthhed-vM7CBdSBX%3DFPHMZ0BBg%40mail.gmail.com?utm_medium=email&utm_source=footer>> .
>

[John Allwine]

Thanks Cern! I simply took out that chunk of code and everything seems to work.