Hi Carles > Hi Alex, Andrei, > > thanks for your reply. Based on your feedback I've tried the > following: > - I have downloaded the patch patch-5.15.86-rt56.patch from > https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.15/ and stored > in ./meta-raspberrypi/recipes-kernel/linux/files > - I have created a file linux-raspberrypi_%.bbappend in > ./meta-raspberrypi/recipes-kernel/linux > - I have created a .cfg file with CONFIG_PREEMPT_RT_FULL = y in > ./meta-raspberrypi/recipes-kernel/linux/files > - I have added both patch and cfg file in bbappend using > SRC_URI:append:rpi. > > I can observe the following: > - patch and cfg files are available in > ./build/tmp/work/raspberrypi4_64-agl-linux/linux-raspberrypi/1_5.15.34+gitAUTOINC+e1b976ee4f_0086da6acd-r0 > - new folder linux-raspberrypi4_64-preempt-rt-build is available > inside the folder above. But the problem seems to be that > CONFIG_PREEMPT_RT = y is not applied to the .config file. So it seems > the preempt-rt kernel is built but without the full preempt-rt > support. > - When I do bitbake linux-raspberrypi -c menuconfig I cannot select > the full real time preempt kernel, only preemptible option available > is --> Preemptible Kernel (Low-Latency Desktop). Fully Preemptible > Kernel (Real-Time) is not available. > - When I flash the image in the Rpi4 and run uname -r I see that the > rt kernel has been built --> 5.15.34.rt56.v8 > - but only with PREEMPT option but without RT when I do uname -v --> > #1 SMP PREEMPT Tue Aug 9 21:20:00 UTC 2022 (without RT). > > I have tried building linux-yocto-rt for qemu and there I see that > CONFIG_PREEMP_RT = y is available in the .config file. Also if I open > menuconfig I have the option to select in General setup --> > Preemption Model --> Fully Preemptible Kernel (Real-Time) > > If you can provide any hints on what am I missing it would be highly > appreciated. >
Have you managed to go any further with your investigation regarding PREEMPT-RT on RPi4-64? > Best Regards, > Carles Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Erika Unter HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: [email protected]
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