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Hamzalihi avatar Ubuntu

Installing PREEMPT_RT kernel on ubuntu 20.04.5 LTS (focal)

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Hamzalihi

I am trying to install a real kernel that I need for an application (controlling a UR robot) and I followed the UR driver tutorial on git hub on how to install it.

First I ran the command:

$ uname -r
5.15.0-69-generic

Infact I run -a to show it all.

$ uname -a
Linux Hamza 5.15.0-69-generic #76~20.04.1-Ubuntu SMP Mon Mar 20 15:54:19 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

I also have a Intel® Core™ i5.

I now want to install a version close to my version which is version 5.14.2. Here are all the commands I do:

mkdir ~/kernel
cd ~/kernel
wget https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/patch-5.14.2-rt21.patch.xz
wget https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.14/patch-5.14.2-rt21.patch.sign
wget https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/linux-5.14.2.tar.xz
wget https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/linux-5.14.2.tar.sign
xz -dk patch-5.14.2-rt21.patch.xz
xz -d linux-5.14.2.tar.xz

Then there is the verification step which I skipped.

tar xf linux-5.14.2.tar
cd linux-5.14.2
xzcat ../patch-5.14.2-rt21.patch.xz | patch -p1
make oldconfig

Here I press 4 for Fully Preemptible Kernel (RT) (PREEMPT_RT_FULL) (NEW) and for the rest I press enter.

I in the end build the kernel:

make -j `getconf _NPROCESSORS_ONLN` deb-pkg

The error I get:

make[2]: *** [debian/rules:7: build-arch] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2
make[1]: *** [scripts/Makefile.package:77: deb-pkg] Error 2
make: *** [Makefile:1569: deb-pkg] Error 2

And here are the different warnings I get during the compilation.

dpkg-source: warning: source directory 'linux-5.14.2' is not <sourcepackage>-<upstreamversion> 'linux-upstream-5.14.2-rt21'
dpkg-source: warning: .orig directory name linux-5.14.2.orig is not <package>-<upstreamversion> (wanted linux-upstream-5.14.2-rt21.orig)
dpkg-source: warning: ignoring deletion of file .scmversion
dpkg-source: warning: the diff modifies the following upstream files: 
dpkg-source: warning: missing information for output field Standards-Version
arch/x86/hyperv/hv_apic.c:240:1: warning: the frame size of 1032 bytes is larger than 1024 bytes [-Wframe-larger-than=]
fs/jffs2/xattr.c:887:1: warning: the frame size of 1144 bytes is larger than 1024 bytes [-Wframe-larger-than=]887 | }

I really hope someone can see where I went wrong or has a better method for installing because other solutions such as these did not work; One,two and this very recent one but no answers

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richbl
**Welcome to the Ask Ubuntu community.** It would seem to me that the issue has more to do with the procedure that you're following, as my first observation is that the kernel you downloaded (5.14) is [no longer maintained according to the Linux Foundation site](https://wiki.linuxfoundation.org/realtime/preempt_rt_versions) referenced in [the Git project procedure that you're following](https://github.com/UniversalRobots/Universal_Robots_ROS_Driver/blob/master/ur_robot_driver/doc/real_time.md). You may want to work directly with the project owner.
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