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--- comfilepi:compile_a_real-time_kernel:index [2023/05/12 10:08]
COMFILE Technology [Troubleshooting]
+++ comfilepi:compile_a_real-time_kernel:index [2023/11/22 08:57] (current)
COMFILE Technology [Deploy to the ComfilePi]
@@ Line 1: / Line 1: @@
 ====== Compile and Deploy a Real-Time Kernel to the ComfilePi ======
-The generic kernel employed the the default ComfilePi operating system is not a real-time kernel.  That is fine for many, if not most, use cases.  For those use cases that may require real-time operation, we provide the following procedure.  Please note that COMFILE Technology does not maintain the Raspberry Pi kernel or the Linux real-time patches, so those wishing to employ this capability should assume responsibility for it.
+The generic kernel employed the the default ComfilePi operating system is not a real-time kernel.  That is fine for many, if not most, use cases.  For those use cases that may require real-time operation, we provide the following procedure.
+In addition to compiling and deploying a realtime kernel, [[comfilepi:improving_real-time_performance:index|other OS configurations]] may be necessary to improve the realtime performance.
+Please note that COMFILE Technology does not maintain the Raspberry Pi kernel or the Linux real-time patches, so those wishing to employ this capability should assume responsibility for it.
 ===== Kernel Versioning =====
-The Raspberry Pi Foundation maintains the kernel for Raspberry Pi-based products at https://github.com/raspberrypi/linux. The real-time kernel patches are maintained by a different group at https://cdn.kernel.org/pub/linux/kernel/projects/rt/. Compile errors and/or patch errors can arise if the 3 digit version number of the Raspberry Pi kernel and the real time patch do not match.  The Raspberry Pi Foundation and the real-time patch maintainers do no coordinate their releases, so one must search the [[https://github.com/raspberrypi/linux/commits/rpi-5.10.y/Makefile|kernel's Makefile version history]] for a "Linux x.y.z" commit that matches the real-time kernel patch version, then use the "Merge remote-tracking..." commit that follows it.  At the time of writing this, the latest such commit for the 5.10.y branch was here:
+The Raspberry Pi Foundation maintains the kernel for Raspberry Pi-based products at https://github.com/raspberrypi/linux. The real-time kernel patches are maintained by a different group at https://cdn.kernel.org/pub/linux/kernel/projects/rt/. Compile errors and/or patch errors can arise if the 3 digit version number of the Raspberry Pi kernel and the real time patch do not match.  The Raspberry Pi Foundation and the real-time patch maintainers do no coordinate their releases, so one must search the [[https://github.com/raspberrypi/linux/commits/rpi-6.1.y|kernel's commit history]] for a "Linux x.y.z" commit that matches the real-time kernel patch version, then use the "Merge remote-tracking..." commit that follows it.  At the time of writing this, the latest such commit for the 5.10.y branch was here:
 {{ :comfilepi:compile_a_real-time_kernel:commit.png }}
@@ Line 11: / Line 14: @@
 ===== Build Script =====
-Given the versioning limitations explained above, the following shell script cross-compiles kernel version 5.10.35.  It will download all necessary software and source code, cross-compile the real-time kernel, and package the resulting assests for deployment to a ComfilePi panel PC.  It was tested on an Ubuntu 20.04 x64 workstation, and in an Ubuntu 20.04 instance of [[https://docs.microsoft.com/en-us/windows/wsl/about|Windows Subsystem for Linux]].
+Given the versioning limitations explained above, the following shell script cross-compiles kernel version 6.1.26.  It will download all necessary software and source code, cross-compile the real-time kernel, and package the resulting assests for deployment to a ComfilePi panel PC.  It was tested on a Debian instance of [[https://docs.microsoft.com/en-us/windows/wsl/about|Windows Subsystem for Linux]].
 <code bash>
 #!/bin/bash
-KERNEL_VERSION=5.10
+# You may need to install the following packages
-RT_PATCH_VERSION=$KERNEL_VERSION.35-rt39
+# apt update -y
-COMMIT_HASH=53a5ac4935c500d32bfc465551cc5107e091c09c
+# apt install -y wget git bc bison flex libssl-dev make libc6-dev libncurses5-dev crossbuild-essential-$ARCH
-DEFCONFIG=bcm2709_defconfig
-ARCH=arm
-TARGET=arm-linux-gnueabihf
+KERNEL_VERSION=6.1
+RT_PATCH_VERSION=$KERNEL_VERSION.26-rt8
+COMMIT_HASH=dbcb82357ef21be47841ba39d117b626d715af31
+DEFCONFIG=bcm2711_defconfig
+ARCH=arm64
+TARGET=aarch64-linux-gnu
+KERNEL_NAME=kernel8
 KERNEL_BRANCH=rpi-$KERNEL_VERSION.y
 COMPILER=$TARGET-
 # All work will be done in $PWD/rtkernel.  The final result will be packaged as $PWD/rtkernel/result
-PROJECT_DIR=`pwd`/rtkernel
+WORK_DIR=`pwd`/rtkernel
-rm -rf $PROJECT_DIR
+rm -rf $WORK_DIR
-mkdir $PROJECT_DIR
+mkdir $WORK_DIR
-cd $PROJECT_DIR
+cd $WORK_DIR
-# install necessary packages
+# download the kernel
-sudo apt update
-sudo apt install -y wget git bc bison flex libssl-dev make libc6-dev libncurses5-dev crossbuild-essential-armhf
-# download the kernel and RT patch
 git clone --depth=1 --branch $KERNEL_BRANCH https://github.com/raspberrypi/linux
+# download the RT patch
 wget http://cdn.kernel.org/pub/linux/kernel/projects/rt/$KERNEL_VERSION/older/patch-$RT_PATCH_VERSION.patch.gz
 gunzip patch-$RT_PATCH_VERSION.patch.gz
+# Need this to get precisely the correct kernel version
 cd linux
-# Need this to get precisely the correct kernel version
 git fetch origin $COMMIT_HASH
-git checkout $COMMIT_HASH
+git reset --hard $COMMIT_HASH
 # Patch the kernel
 patch -p1 < ../patch-$RT_PATCH_VERSION.patch
-# Prepare configuration
+ # Prepare configuration
-make ARCH=$ARCH CROSS_COMPILE=$COMPILER mrproper
 make ARCH=$ARCH CROSS_COMPILE=$COMPILER $DEFCONFIG
+ # Configure to use the "Fully Preemptible Kernel (Real-Time)" kernel
+./scripts/config --set-val CONFIG_PREEMPT_RT y
+./scripts/config --set-val CONFIG_RCU_BOOST y
+./scripts/config --set-val CONFIG_RCU_BOOST_DELAY 500
+./scripts/config --set-val CONFIG_RCU_NOCB_CPU y
+./scripts/config --set-val CONFIG_NO_HZ_FULL y
+./scripts/config --set-val CONTEXT_TRACKING_USER_FORCE n
+./scripts/config --set-val RCU_NOCB_CPU_DEFAULT_ALL n
+./scripts/config --set-val RCU_NOCB_CPU_CB_BOOST y
+# Compile
+make -j32 ARCH=$ARCH CROSS_COMPILE=$COMPILER Image.gz modules dtbs
-# Configure the kernel
+# copy assets to the root file system
-# At this step, select "Virtualization" and deselect "Kernel-based Virtual Machine (KVM) support"
+make ARCH=$ARCH CROSS_COMPILE=$COMPILER INSTALL_MOD_PATH=modules_to_install modules_install
-# Then, select "General setup" --> "Preemption Model" --> "Fully Preemptible Kernel (Real-Time)"
-make ARCH=$ARCH CROSS_COMPILE=$COMPILER menuconfig
-# Compile
-make -j16 ARCH=$ARCH CROSS_COMPILE=$COMPILER zImage modules dtbs
+ # Out of linux, out of work_dir
+cd ../../
 # copy assets to the $PROJECT_DIR/result directory
-RESULT_DIR=$PROJECT_DIR/result
+RESULT_DIR=$WORK_DIR/result
-mkdir $RESULT_DIR
+mkdir -p $RESULT_DIR/boot/overlays
-EXT4_DIR=$RESULT_DIR/ext4
+cp ${WORK_DIR}/linux/arch/$ARCH/boot/Image.gz ${RESULT_DIR}/boot/$KERNEL_NAME.img
-FAT32_DIR=$RESULT_DIR/fat32
+cp -r ${WORK_DIR}/linux/modules_to_install/lib/* ${RESULT_DIR}/lib/
-mkdir $FAT32_DIR
+cp ${WORK_DIR}/linux/arch/$ARCH/boot/dts/broadcom/*.dtb ${RESULT_DIR}/boot/
-mkdir $EXT4_DIR
+cp ${WORK_DIR}/linux/arch/$ARCH/boot/dts/overlays/*.dtb* ${RESULT_DIR}/boot/overlays/
-make ARCH=$ARCH CROSS_COMPILE=$COMPILER INSTALL_MOD_PATH=$EXT4_DIR modules_install
+cp ${WORK_DIR}/linux/arch/$ARCH/boot/dts/overlays/README ${RESULT_DIR}/boot/overlays/
-cp arch/$ARCH/boot/zImage $FAT32_DIR/
-cp arch/$ARCH/boot/dts/*.dtb $FAT32_DIR/
-mkdir $FAT32_DIR/overlays
-cp arch/$ARCH/boot/dts/overlays/*.dtb* $FAT32_DIR/overlays/
-cp arch/$ARCH/boot/dts/overlays/README $FAT32_DIR/overlays/
 </code>
 ===== Deploy to the ComfilePi =====
-After running the build script above, the //rtkernel/result// directory will contain 2 directories: //fat32// and //ext4//.  The //fat32// directory contains assets that must be deployed to the ComfilePi's FAT32 partition (i.e. the ///boot// directory) and the //ext4// directory contains assets that must be deployed to the ComfilePi's operating system root partition (i.e. the ///// directory).
+After running the build script above, the //rtkernel/result// directory will contain 2 directories: //boot// and //lib//.  The //boot// directory contains assets that must be deployed to the ComfilePi's FAT32 partition (i.e. the ///boot// directory) and the //lib// directory contains assets that must be deployed to the ComfilePi's operating system root partition (i.e. the ///lib// directory).
+On the build PC:
 <code bash>
 # Package up the result into a single file
-tar czf rtkernel.tgz rtkernel/result/*
+tar czf rtkernel.tgz -C rtkernel/result/ .
 # transfer the file to the ComfilePi
@@ Line 90: / Line 100: @@
 </code>
+[[http://downloads.comfiletech.com/ComfilePi/realtime/rtkernel_6.1.26-rt8.tgz|Download rtkernel_6.1.26-rt8.tgz]] (MD5: cadb563fc3cc61e9a2a5fc571a08004a)
+On the ComfilePi:
 <code bash>
-# Unpack the files
+# Install the kernel assets
-tar xzf rtkernel.tgz
+sudo tar xzf rtkernel.tgz --directory / --keep-directory-symlink --no-same-owner
-cd rtkernel/result
-# Copy files to the /boot directory
-sudo cp fat32/zImage /boot/kernel7.img
-sudo cp fat32/*.dtb /boot/
-sudo cp fat32/overlays/*.dtb* /boot/overlays/
-sudo cp fat32/overlays/README /boot/overlays/
-# Copy files to the / directory
-sudo cp -rd ext4/lib/* /lib
 </code>
@@ Line 109: / Line 111: @@
 <code>
 $uname -a
-Linux raspberrypi 5.10.35-rt39-v7+ #1 SMP PREEMPT_RT Thu Jun 24 11:13:50 KST 2021 armv7l GNU/Linux
+Linux raspberrypi 6.1.21-rt8-v8+ #1 SMP PREEMPT_RT Fri May 12 10:19:19 KST 2023 aarch64 GNU/Linux
 </code>

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