From 9054cc788a22980e8688dfaacc9b0d3f19304c95 2018-10-22 19:32:24
From: drtyhlpr <mail@jwagner.eu>
Date: 2018-10-22 19:32:24
Subject: [PATCH] fix: kernel compilation, add ccache support

---

diff --git a/README.md b/README.md
index 0ba14f8..d470b0f 100644
--- a/README.md
+++ b/README.md
@@ -295,6 +295,12 @@ Install kernel headers with built kernel.
 ##### `KERNEL_MENUCONFIG`=false
 Start `make menuconfig` interactive menu-driven kernel configuration. The script will continue after `make menuconfig` was terminated.
 
+##### `KERNEL_OLDDEFCONFIG`=false
+Run `make olddefconfig` to automatically set all new kernel configuration options to their recommended default values.
+
+##### `KERNEL_CCACHE`=false
+Compile the kernel using ccache. This speeds up kernel recompilation by caching previous compilations and detecting when the same compilation is being done again.
+
 ##### `KERNEL_REMOVESRC`=true
 Remove all kernel sources from the generated OS image after it was built and installed.
 
diff --git a/bootstrap.d/13-kernel.sh b/bootstrap.d/13-kernel.sh
index 45934be..17d89bf 100644
--- a/bootstrap.d/13-kernel.sh
+++ b/bootstrap.d/13-kernel.sh
@@ -25,9 +25,9 @@ if [ "$BUILD_KERNEL" = true ] ; then
 
     # Fetch current RPi2/3 kernel sources
     if [ -z "${KERNEL_BRANCH}" ] ; then
-      as_nobody git -C "${temp_dir}" clone --depth=1 "${KERNEL_URL}" linux
+      as_nobody -H git -C "${temp_dir}" clone --depth=1 "${KERNEL_URL}" linux
     else
-      as_nobody git -C "${temp_dir}" clone --depth=1 --branch "${KERNEL_BRANCH}" "${KERNEL_URL}" linux
+      as_nobody -H git -C "${temp_dir}" clone --depth=1 --branch "${KERNEL_BRANCH}" "${KERNEL_URL}" linux
    fi
     
     # Copy downloaded kernel sources
@@ -87,18 +87,36 @@ if [ "$BUILD_KERNEL" = true ] ; then
       # Load default raspberry kernel configuration
       make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" "${KERNEL_DEFCONFIG}"
 
+      # Copy custom kernel configuration file
       if [ ! -z "$KERNELSRC_USRCONFIG" ] ; then
         cp $KERNELSRC_USRCONFIG ${KERNEL_DIR}/.config
       fi
 
+      # Set kernel configuration parameters to their default values
+      if [ "$KERNEL_OLDDEFCONFIG" = true ] ; then
+        make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" olddefconfig
+      fi
+
       # Start menu-driven kernel configuration (interactive)
       if [ "$KERNEL_MENUCONFIG" = true ] ; then
         make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" menuconfig
       fi
     fi
 
-    # Cross compile kernel and modules
-    make -C "${KERNEL_DIR}" -j${KERNEL_THREADS} ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" "${KERNEL_BIN_IMAGE}" modules dtbs
+    # Use ccache to cross compile the kernel
+    if [ "$KERNEL_CCACHE" = true ] ; then
+      cc="ccache ${CROSS_COMPILE}gcc"
+    else
+      cc="${CROSS_COMPILE}gcc"
+    fi
+
+    # Cross compile kernel and dtbs
+    make -C "${KERNEL_DIR}" -j${KERNEL_THREADS} ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" CC="${cc}" "${KERNEL_BIN_IMAGE}" dtbs
+
+    # Cross compile kernel modules
+    if [ $(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config") ] ; then
+      make -C "${KERNEL_DIR}" -j${KERNEL_THREADS} ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" CC="${cc}" modules
+    fi
   fi
 
   # Check if kernel compilation was successful
@@ -110,12 +128,16 @@ if [ "$BUILD_KERNEL" = true ] ; then
 
   # Install kernel modules
   if [ "$ENABLE_REDUCE" = true ] ; then
-    make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=../../.. modules_install
+    if [ $(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config") ] ; then
+      make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_MOD_STRIP=1 INSTALL_MOD_PATH=../../.. modules_install
+    fi
   else
-    make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_MOD_PATH=../../.. modules_install
+    if [ $(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config") ] ; then
+      make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_MOD_PATH=../../.. modules_install
+    fi
 
     # Install kernel firmware
-    if [ $(cat ./Makefile | grep "^firmware_install:") ] ; then
+    if [ $(grep "^firmware_install:" "${KERNEL_DIR}/Makefile") ] ; then
       make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" INSTALL_FW_PATH=../../../lib firmware_install
     fi
   fi
@@ -134,18 +156,36 @@ if [ "$BUILD_KERNEL" = true ] ; then
   # Copy kernel configuration file to the boot directory
   install_readonly "${KERNEL_DIR}/.config" "${R}/boot/config-${KERNEL_VERSION}"
 
-  # Copy dts and dtb device tree sources and binaries
+  # Prepare device tree directory
   mkdir "${BOOT_DIR}/overlays"
   
   # Ensure the proper .dtb is located
   if [ "$KERNEL_ARCH" = "arm" ] ; then
-    install_readonly "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/"*.dtb "${BOOT_DIR}/"
+    for dtb in "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/"*.dtb ; do
+      if [ -f "${dtb}" ] ; then
+        install_readonly "${dtb}" "${BOOT_DIR}/"
+      fi
+    done
   else
-    install_readonly "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/broadcom/"*.dtb "${BOOT_DIR}/"
+    for dtb in "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/broadcom/"*.dtb ; do
+      if [ -f "${dtb}" ] ; then
+        install_readonly "${dtb}" "${BOOT_DIR}/"
+      fi
+    done
   fi
 
-  install_readonly "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/overlays/"*.dtb* "${BOOT_DIR}/overlays/"
-  install_readonly "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/overlays/README" "${BOOT_DIR}/overlays/README"
+  # Copy compiled dtb device tree files
+  if [ -d "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/overlays" ] ; then
+    for dtb in "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/overlays/"*.dtb ; do
+      if [ -f "${dtb}" ] ; then
+        install_readonly "${dtb}" "${BOOT_DIR}/overlays/"
+      fi
+    done
+
+    if [ -f "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/overlays/README" ] ; then
+      install_readonly "${KERNEL_DIR}/arch/${KERNEL_ARCH}/boot/dts/overlays/README" "${BOOT_DIR}/overlays/README"
+    fi
+  fi
 
   if [ "$ENABLE_UBOOT" = false ] ; then
     # Convert and copy kernel image to the boot directory
@@ -159,11 +199,16 @@ if [ "$BUILD_KERNEL" = true ] ; then
   if [ "$KERNEL_REMOVESRC" = true ] ; then
     rm -fr "${KERNEL_DIR}"
   else
-    make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" modules_prepare
+    # Prepare compiled kernel modules
+    if [ $(grep "CONFIG_MODULES=y" "${KERNEL_DIR}/.config") ] ; then
+      if [ $(grep "^modules_prepare:" "${KERNEL_DIR}/Makefile") ] ; then
+        make -C "${KERNEL_DIR}" ARCH="${KERNEL_ARCH}" CROSS_COMPILE="${CROSS_COMPILE}" modules_prepare
+      fi
 
-    # Create symlinks for kernel modules
-    chroot_exec ln -sf /usr/src/linux "/lib/modules/${KERNEL_VERSION}/build"
-    chroot_exec ln -sf /usr/src/linux "/lib/modules/${KERNEL_VERSION}/source"
+      # Create symlinks for kernel modules
+      chroot_exec ln -sf /usr/src/linux "/lib/modules/${KERNEL_VERSION}/build"
+      chroot_exec ln -sf /usr/src/linux "/lib/modules/${KERNEL_VERSION}/source"
+    fi
   fi
 
 else # BUILD_KERNEL=false
diff --git a/rpi23-gen-image.sh b/rpi23-gen-image.sh
index 7a0adb3..7f6970b 100755
--- a/rpi23-gen-image.sh
+++ b/rpi23-gen-image.sh
@@ -175,6 +175,9 @@ KERNEL_THREADS=${KERNEL_THREADS:=1}
 KERNEL_HEADERS=${KERNEL_HEADERS:=true}
 KERNEL_MENUCONFIG=${KERNEL_MENUCONFIG:=false}
 KERNEL_REMOVESRC=${KERNEL_REMOVESRC:=true}
+KERNEL_OLDDEFCONFIG=${KERNEL_OLDDEFCONFIG:=false}
+KERNEL_CCACHE=${KERNEL_CCACHE:=false}
+
 if [ "$KERNEL_ARCH" = "arm64" ] ; then
   KERNEL_BIN_IMAGE=${KERNEL_BIN_IMAGE:="Image"}
 else
@@ -269,6 +272,11 @@ if [ "$KERNEL_MENUCONFIG" = true ] ; then
   REQUIRED_PACKAGES="${REQUIRED_PACKAGES} libncurses5-dev"
 fi
 
+# Add ccache compiler cache for (faster) kernel cross (re)compilation
+if [ "$KERNEL_CCACHE" = true ] ; then
+  REQUIRED_PACKAGES="${REQUIRED_PACKAGES} ccache"
+fi
+
 # Stop the Crypto Wars
 if [ "$DISABLE_FBI" = true ] ; then
   ENABLE_CRYPTFS=true