Merge branch 'ci'

.gitattributes

-*.deb filter=lfs diff=lfs merge=lfs -text

.gitlab-ci.yml

+stages:
+  - build
+
+build-kernel:
+  image: ubuntu:bionic
+  stage: build
+  artifacts:
+    paths:
+      - "*.deb"
+  script:
+    - apt-get update
+    - apt-get install -y build-essential curl bison flex bc rsync kmod cpio lsb-release libssl-dev
+    - ./compile.bash
+  tags:
+  - highmem

README.md

 # Realtime Kernel for Ubuntu 18.4
 
-⚠ this repository uses git-lfs. when cloning, make sure LFS is installed locally.
+These are `deb` packages built for Ubuntu Bionic. The packages are created following advice from [Stackoverflow](https://stackoverflow.com/questions/51669724/install-rt-linux-patch-for-ubuntu) and the [Panda manuals](https://frankaemika.github.io/docs/installation_linux.html#setting-up-the-real-time-kernel).
 
-These are deb packages built for Ubuntu Bionic.
+## Information
 
-Used Kernel sources:
-- kernel `linux-5.4.19-rt11_5.4.19-rt11.orig.tar.gz`
-- realtime patch `linux-5.4.19-rt11_5.4.19-rt11-1.diff.gz`
+The kernel is built automatically by the CI from the [linux kernel sources](https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/) version 5.4, using the latest kernel version for which a [real time patch](https://mirrors.edge.kernel.org/pub/linux/kernel/projects/rt/5.4/) is available. For more information on how the kernel is built, please review the `compile.bash` script.
 
-Kernel config:
-- Preemption Model: Fully Preemptible Kernel (RT)
+It's `config` file is based on the config provided by a Unbuntu Bionic installation with two changes:
+- The `preemption model` ist set to `Fully Preemptible Kernel (RT)`.
+- `Compile the kernel with debug info (DEBUG_INFO)` is set to `no`.
+
+Before the build, if the new kernel version contains new config keys, the corresponding values are set to their defaults.
 
 ## Installation
 
-- ⚠ make sure secureboot is disabled.
-- simply install the packages using `dpkg -i`
+- **⚠ ATTENTION** Make sure secureboot is disabled. Currently, the compiled kernel is unsigned and thus, will not work with secureboot.
+- **⚠ ATTENTION** The repository does not contain the kernel packges, they are built by the CI and and can be downloaded.
+- [Download the latest kernel packages built by the CI](https://git-st.inf.tu-dresden.de/ceti/realtime-kernel/-/jobs/artifacts/master/browse?job=build-kernel).
+- Install the packages using `dpkg -i`.
 
 ## Verifying that the Realtime Kernel is Running
 
-- reboot after kernel installation, selecting the new kernel in Grub
-- run `uname -a`, the result should contains `PREEMPT RT`
+- Reboot after kernel installation, selecting the new kernel in the boot loader.
+- Run `uname -a`, the result should contain the kernel version number from the installed `deb` package as well as `PREEMPT RT`.
 
 ## Set User Permissions
 
-- add a group named realtime and add the user controlling your robot to this group:
+- Add a group named realtime and add the user controlling your robot to this group:
     ```
     sudo addgroup realtime
     sudo usermod -a -G realtime $(whoami)
     ```
-- add the following limits to the realtime group in /etc/security/limits.conf:
+- Add the following limits to the realtime group in /etc/security/limits.conf:
     ```
     @realtime soft rtprio 99
     @realtime soft priority 99
@@ -37,4 +40,5 @@ Kernel config:
     @realtime hard priority 99
     @realtime hard memlock 102400
     ```
-- log out and in again (or restart)
+- Log off and on again to let the group assignment and realtime priorities take effect (or, to be safe, restart). Use the command `groups` to check if the the current user belongs to the realtime group.
\ No newline at end of file
+

compile.bash

+#!/bin/bash
+
+# get current kernel and realtime patch version
+
+FILE=`curl -s https://mirrors.edge.kernel.org/pub/linux/kernel/projects/rt/5.4/`
+KERNEL=`echo $FILE | sed -n 's/.*patch-5.4.\(.*\)-rt.*.patch.gz.*/\1/p'`
+RTPATCH=`echo $FILE | sed -n 's/.*patch-5.4..*-rt\(.*\).patch.gz.*/\1/p'`
+echo "using kernel 5.4.$KERNEL with realtime patch $RTPATCH"
+
+# get kernel file names and location
+
+KERNELURL=https://www.kernel.org/pub/linux/kernel/v5.x/
+KERNELNAME=linux-5.4.${KERNEL}
+KERNELFILE=linux-5.4.${KERNEL}.tar
+KERNELFILEXZ=linux-5.4.${KERNEL}.tar.xz
+KERNELSIGN=linux-5.4.${KERNEL}.tar.sign
+PATCHURL=https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/
+PATCHFILE=patch-5.4.${KERNEL}-rt${RTPATCH}.patch
+PATCHFILEXZ=patch-5.4.${KERNEL}-rt${RTPATCH}.patch.xz
+PATCHSIGN=patch-5.4.${KERNEL}-rt${RTPATCH}.patch.sign
+
+# download kernel
+
+echo "downloading kernel from ${PATCHURL}${PATCHFILE}"
+curl -SLO ${KERNELURL}${KERNELFILEXZ}
+curl -SLO ${KERNELURL}${KERNELSIGN}
+echo "downloading patch from ${PATCHURL}${PATCHSIGN}"
+curl -sLO ${PATCHURL}${PATCHFILEXZ}
+curl -sLO ${PATCHURL}${PATCHSIGN}
+
+# unzip kernel (required for verification)
+
+xz -d $KERNELFILEXZ
+xz -d $PATCHFILEXZ
+
+# verify the kernel
+
+gpg --verify --keyserver hkp://keys.gnupg.net --auto-key-retrieve $KERNELSIGN
+gpg --verify --keyserver hkp://keys.gnupg.net --auto-key-retrieve $PATCHSIGN
+
+# unpack kernel
+
+tar xf $KERNELFILE
+cd $KERNELNAME
+patch -p1 < ../${PATCHFILE}
+
+# build the kernel
+
+# use the kernel config build on a normal ubuntu 18.4
+cp ../config .config
+# update config with defaults if new options have been added
+make olddefconfig
+make deb-pkg