build_mixed: Add a generic script for GKI mixed builds

As more vendors adopt GKI, it's useful to provide a generic script that
can be used to create GKI mixed builds.

Bug: 184667897
Signed-off-by: J. Avila <[email protected]>
Change-Id: Ief3be4d5f230526de6cc795cfd9edc0cf4be6118

build_mixed.sh

@@ -0,0 +1,142 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# build_mixed.sh takes as input a GKI source tree or GKI prebuilts as
+#   well as a device kernel source tree, compiles them, and then combines
+#   them into a set of flashable images to boot a GKI build.
+#
+# Usage:
+#   To build the GKI kernel:
+#     GKI_KERNEL_BUILD_CONFIG=path/to/gki/config \
+#       DEVICE_KERNEL_BUILD_CONFIG=path/to/device/config \
+#       build_mixed.sh
+#
+#   To use GKI prebuilts:
+#      GKI_KERNEL_PREBUILTS_DIR=path/to/gki/prebuilts \
+#        DEVICE_KERNEL_BUILD_CONFIG=path/to/device/config \
+#        build_mixed.sh
+#
+#   Note that you must always set one of either GKI_KERNEL_PREBUILTS_DIR or
+#   GKI_KERNEL_BUILD_CONFIG.
+#
+# The following environment variables are considered during execution:
+#
+#   DEVICE_KERNEL_BUILD_CONFIG
+#     The build config for the device kernel to be passed into build.sh. This
+#     config is always required to be set.
+#
+#   GKI_KERNEL_BUILD_CONFIG
+#     The build config for the GKI kernel to be passed into build.sh. This
+#     config is required if you are building the GKI kernel, and is incompatible
+#     with GKI_KERNEL_PREBUILTS_DIR.
+#
+#   GKI_DEFCONFIG_FRAGMENT
+#     An optional path to an additional build.config fragment. Only works if
+#     your base build config supports GKI_DEFCONFIG_FRAGMENT, such as
+#     build.config.gki.aarch64. This is incompatible with GKI_KERNEL_PREBUILTS_DIR.
+#
+#   GKI_KERNEL_PREBUILTS_DIR
+#     A path to a set of GKI prebuilts. These prebuilts can be used to skip the
+#     compilation of the GKI kernel. Incompatible with GKI_KERNEL_BUILD_CONFIG.
+#
+#     The following must be found in this directory to work:
+#       vmlinux
+#       System.map
+#       vmlinux.symvers
+#       modules.builtin
+#       modules.builtin.modinfo
+#       Image.lz4
+
+function print_usage {
+cat << EOF
+$0 takes as input a GKI source tree or GKI prebuilts as
+  well as a device kernel source tree, compiles them, and then combines
+  them into a set of flashable images to boot a GKI build.
+
+Example usage of $0:
+  To build the GKI kernel:
+    GKI_KERNEL_BUILD_CONFIG=path/to/gki/config \\
+      DEVICE_KERNEL_BUILD_CONFIG=path/to/device/config \\
+      $0
+
+  To use GKI prebuilts:
+    GKI_KERNEL_PREBUILTS_DIR=path/to/gki/prebuilts \\
+      DEVICE_KERNEL_BUILD_CONFIG=path/to/device/config \\
+      $0
+
+EOF
+}
+
+function exit_if_error {
+  if [ $1 -ne 0 ]; then
+    echo "ERROR: $2: retval=$1" >&2
+    exit $1
+  fi
+}
+
+function copy_gki_prebuilts {
+  mkdir -p ${DIST_DIR}
+  echo "Copying GKI prebuilts from ${GKI_KERNEL_PREBUILTS_DIR} to ${DIST_DIR}."
+  cp ${GKI_KERNEL_PREBUILTS_DIR}/* ${DIST_DIR}/
+}
+
+function build_gki {
+  echo "Building GKI kernel using ${GKI_KERNEL_BUILD_CONFIG}..."
+  BUILD_CONFIG=${GKI_KERNEL_BUILD_CONFIG} \
+    OUT_DIR=${BASE_OUT}/${GKI_KERNEL_OUT_DIR}/ \
+    DIST_DIR=${DIST_DIR} \
+    SKIP_CP_KERNEL_HDR=1 \
+    build/build.sh KCFLAGS=-Werror "$@"
+  exit_if_error $? "Failed to compile GKI kernel"
+}
+
+function build_device_kernel {
+  echo "Building device kernel using ${DEVICE_KERNEL_BUILD_CONFIG}..."
+  BUILD_CONFIG=${DEVICE_KERNEL_BUILD_CONFIG} \
+    OUT_DIR=${BASE_OUT}/${DEVICE_KERNEL_OUT_DIR}/ \
+    DIST_DIR=${DIST_DIR} \
+    MIXED_BUILD=1 \
+    KBUILD_MIXED_TREE=${GKI_BINARIES_DIR} \
+    build/build.sh KCFLAGS=-Werror "$@"
+  exit_if_error $? "Failed to compile device kernel"
+}
+
+BASE_OUT=${OUT_DIR:-out}/mixed/
+DIST_DIR=${DIST_DIR:-${BASE_OUT}/dist/}
+GKI_KERNEL_OUT_DIR=${GKI_KERNEL_OUT_DIR:-"gki-kernel"}
+DEVICE_KERNEL_OUT_DIR=${DEVICE_KERNEL_OUT_DIR:-"device-kernel"}
+GKI_BINARIES_DIR=$(readlink -m ${DIST_DIR})
+
+if [ -n "${GKI_KERNEL_PREBUILTS_DIR}" ]; then
+  GKI_KERNEL_PREBUILTS_DIR=$(readlink -m "${GKI_KERNEL_PREBUILTS_DIR}")
+fi
+
+if [ -n "${BUILD_CONFIG}" ]; then
+  print_usage
+  exit_if_error 1 "BUILD_CONFIG is not supported for $0"
+fi
+
+if [ -z "${DEVICE_KERNEL_BUILD_CONFIG}" ]; then
+  print_usage
+  exit_if_error 1 "No DEVICE_KERNEL_BUILD_CONFIG set"
+fi
+
+if [ -n "${GKI_KERNEL_PREBUILTS_DIR}" ]; then
+  if [ -n "${GKI_KERNEL_BUILD_CONFIG}" ]; then
+    print_usage
+    exit_if_error 1 "Flags incompatible with GKI_KERNEL_PREBUILTS_DIR detected"
+  elif [ ! -d ${GKI_KERNEL_PREBUILTS_DIR} ]; then
+    exit_if_error 1 "${GKI_KERNEL_PREBUILTS_DIR} does not exist"
+  fi
+elif [ -z "${GKI_KERNEL_BUILD_CONFIG}" ]; then
+  print_usage
+  exit_if_error 1 "Must set GKI_KERNEL_PREBUILTS_DIR or GKI_KERNEL_BUILD_CONFIG"
+fi
+
+if [ -n "${GKI_KERNEL_BUILD_CONFIG}" ]; then
+  build_gki
+else
+  copy_gki_prebuilts
+fi
+
+build_device_kernel