Real time Linux image For Oluxino lime 2

tomio64 · October 26, 2015, 11:53:47 AM

Hello,
i would like if exist RT linux image for Oluxino lime 2 ?
Thank you
Best regards

soenke · October 26, 2015, 02:54:11 PM

Just use the normal image and replace the kernel with a RT kernel, that is the easiest way.
Consider if you _really_ need a hard realtime kernel with RT-patches or if a "normal" preempt-kernel with high-precision-timer could also do the job.

tomio64 · October 27, 2015, 10:44:09 AM

hello,
i want real time for increase capability, of system, but is not with extrem condition.
so can you explain hw i can change simply the kernel , with RT kernel, i never do that, there are some year i have make compilation of kernel with debian, for have kernel more newer.
But i don't remeber how i do that.
So have you link that explain how i can do ?
Thank you,
best regards

soenke · October 27, 2015, 11:19:03 AM

then dont use a RT kernel. The RT kernel wont increase the capability of the system unless you program a realtime application with really high precision timing requirements. If you need RT precision within some miroseconds, use the RT kernel. If you dont care about a +-100µs(?) jitter, use the normal kernel with preemnt and hp-timer.

Howto build a kernel:

http://linux-sunxi.org/Mainline_Kernel_Howto

and mainline u-boot:

https://linux-sunxi.org/Mainline_U-boot

Depening on your current knowledge and learning curve you definitly will have to invest some hours/days until you get your own kernel working.

igorpec · October 27, 2015, 02:32:15 PM

You can use my build script to make 3.4.110 with RT. Patches are there, they are working but are disabled.
https://github.com/igorpecovnik/lib/

For RT:
https://github.com/igorpecovnik/lib/blob/second/patching.sh#L223
Just uncomment this line and build a kernel and/or rather whole image to avoid other problems. In this case you don't need deep knowledge.

soenke · October 27, 2015, 02:58:37 PM

nice work!

tomio64 · October 28, 2015, 11:07:17 AM

hello,
nice job thank you.
is kernel 3.4
can i build RT with kernel 4.2 and higher ?
thank you,
best regards

igorpec · October 28, 2015, 12:43:09 PM

Quote from: tomio64 on October 28, 2015, 11:07:17 AM
hello,
nice job thank you.
is kernel 3.4
can i build RT with kernel 4.2 and higher ?
thank you,
best regards

Those patches works with this kernel (3.4.10*). For 4.x you need a different patch set and since its a new kernel you might need to manually fix patches in any case and you start with no confirmation that it really works.

That is not simple any more.