files not found when installing xenomai kernel with "install_rt_kernel.sh"

Hi,

While trying to install the RTXI software and RT-kernel, I ran into some installation problems.

Basic Information:

RTXI Version: 2.2 Installed from live CD?: No, downloaded with git and compiled from source Ubuntu version: 20.04 LTS

Error Description:

What happened? When trying to install the Xenomai kernel, I stumbled upon some installation issues. A lot of packages were not installed but I was able to circumvent or find a solution for. However, there are two remaining (1 non-essential I think, and 1 that makes the kernel compilation crash).

What was supposed to happen? The kernel was supposed to compile.

What steps will trigger the error? I followed the steps for installing RTXI under the "custom installation" tab. Step 1: Download a generic Linux installation image. --> I downloaded and installed the latest Ubuntu version, 20.04 LTS. Kernel 5.4.0-40-generic. Step 2: Burn the image to a DVD or a USB drive. I installed a live-USB. Step 3. Follow the built-in installer and install the operating system. Done, all works. Step 4. Clone the RTXI repository using git. Done, perfectly works. Step 5. Install RTXI and real-time kernel dependencies. Here I get the first issue that gksu is not found any more since it is deprecated. Step 6. Compile and install the real-time kernel. Here I run into the error after selecting and deselecting the recommended options, in following this sentence: Compilation, depending on your system, can take 10 minutes to a few hours. You are free to leave the system. The install_rt_kernel.sh script will compile the kernel and install it automatically.

Own ideas I found a solution for the broken kernel part, but I don't know how to install it. You can find the post here: https://github.com/torvalds/linux/commit/ad343a98e74e85aa91d844310e797f96fee6983b#diff-89b6591452f7b3e17de375ff48d012c8 I am a bit afraid to just install random things, since I am no kernel expert and I know it might screw up the whole system. Plus, it's for a different kernel version than the one I currently have installed, although it is the correct kernel version for the RTXI-kernel.

Error Message:

Two things actually: The 1st one (I don't think it's that big of a problem):

Package gksu is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

The 2nd one (is a problem because the compilation crashes):

pager.c: In function ‘pager_preexec’:
pager.c:35:12: error: passing argument 2 to restrict-qualified parameter aliases with argument 4 [-Werror=restrict]
   35 |  select(1, &in, NULL, &in, NULL);
      |            ^~~        ~~~
cc1: all warnings being treated as errors

I hope you can help me out.

With kind regards, Tim

Here, the full terminal output of the cpuinfo and the install_rt_kernel.sh command to be complete:

$ cat /proc/cpuinfo
processor   : 0 through 7
vendor_id   : GenuineIntel
cpu family  : 6
model       : 60
model name  : Intel(R) Core(TM) i7-4790 CPU @ 3.60GHz
stepping    : 3
microcode   : 0x28
cpu MHz     : 898.139
cache size  : 8192 KB
physical id : 0
siblings    : 8
core id     : 3
cpu cores   : 4
apicid      : 7
initial apicid  : 7
fpu     : yes
fpu_exception   : yes
cpuid level : 13
wp      : yes
flags       : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm cpuid_fault epb invpcid_single pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid ept_ad fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt dtherm ida arat pln pts md_clear flush_l1d
bugs        : cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit srbds
bogomips    : 7183.15
clflush size    : 64
cache_alignment : 64
address sizes   : 39 bits physical, 48 bits virtual
power management:

output for "install_rt_kernel.sh" can be found in the attachment. xenomai_error.txt

RTXI / rtxi