chore: import upstream snapshot with attribution

kernel/Makefile

@@ -0,0 +1,74 @@
+# Copyright © 2025-2026 Apple Inc. and the Containerization project authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+KSOURCE ?= https://cdn.kernel.org/pub/linux/kernel/v6.x/linux-6.18.5.tar.xz
+KIMAGE ?= kernel-build:0.1
+MAKEFILE_DIR := $(patsubst %/,%,$(dir $(abspath $(lastword $(MAKEFILE_LIST)))))
+GIT_VERSION := $(shell git -C $(MAKEFILE_DIR) rev-parse --short=12 HEAD 2>/dev/null || echo unknown)
+TARGET_ARCH ?=
+
+# Resolve the effective target arch (TARGET_ARCH override, else host).
+EFFECTIVE_ARCH := $(if $(TARGET_ARCH),$(TARGET_ARCH),$(shell uname -m))
+ifneq (,$(filter $(EFFECTIVE_ARCH),aarch64))
+EFFECTIVE_ARCH := arm64
+endif
+ifneq (,$(filter $(EFFECTIVE_ARCH),amd64))
+EFFECTIVE_ARCH := x86_64
+endif
+
+# Compressed (vmlinuz) for x86_64 bzImage; uncompressed (vmlinux) for arm64 Image.
+ifeq ($(EFFECTIVE_ARCH),x86_64)
+KERNEL_OUTPUT := vmlinuz-x86_64
+else
+KERNEL_OUTPUT := vmlinux-arm64
+endif
+
+BIN_DIR := $(abspath $(MAKEFILE_DIR)/../bin)
+
+.DEFAULT_GOAL := all
+
+.PHONY: all
+all: kernel-build-image
+all: kernel-build
+all: kernel-install
+
+.PHONY: kernel-build-image
+kernel-build-image:
+	container build $(MAKEFILE_DIR)/image -f $(MAKEFILE_DIR)/image/Dockerfile -t ${KIMAGE}
+
+.PHONY: kernel-build
+kernel-build:
+ifeq (,$(wildcard $(MAKEFILE_DIR)/source.tar.xz))
+	curl -SsL -o $(MAKEFILE_DIR)/source.tar.xz ${KSOURCE}
+endif
+	container run \
+		--cpus 8 \
+		--rm \
+		--memory 16g \
+		-v $(MAKEFILE_DIR):/kernel \
+		--env LOCALVERSION=-cz-${GIT_VERSION} \
+		$(if $(TARGET_ARCH),--env TARGET_ARCH=$(TARGET_ARCH),) \
+		--cwd /kernel \
+		${KIMAGE} \
+		/bin/bash -c "./build.sh"
+
+.PHONY: kernel-install
+kernel-install:
+	@mkdir -p $(BIN_DIR)
+	@cp -L $(MAKEFILE_DIR)/$(KERNEL_OUTPUT) $(BIN_DIR)/$(KERNEL_OUTPUT)
+	@echo "Installed $(KERNEL_OUTPUT) -> $(BIN_DIR)/$(KERNEL_OUTPUT)"
+
+.PHONY: x86_64
+x86_64:
+	$(MAKE) all TARGET_ARCH=x86_64