chore: import upstream snapshot with attribution

Sources/Containerization/Kernel.swift

@@ -0,0 +1,101 @@
+//===----------------------------------------------------------------------===//
+// 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.
+//===----------------------------------------------------------------------===//
+
+import Foundation
+import Logging
+
+/// An object representing a Linux kernel used to boot a virtual machine.
+/// In addition to a path to the kernel itself, this type stores relevant
+/// data such as the commandline to pass to the kernel, and init arguments.
+public struct Kernel: Sendable, Codable {
+    /// The command line arguments passed to the kernel on boot.
+    public struct CommandLine: Sendable, Codable {
+        public static let kernelDefaults = [
+            "console=hvc0",
+            "tsc=reliable",
+        ]
+
+        /// Adds the debug argument to the kernel commandline.
+        mutating public func addDebug() {
+            self.kernelArgs.append("debug")
+        }
+
+        /// Adds a panic level to the kernel commandline.
+        mutating public func addPanic(level: Int) {
+            self.kernelArgs.append("panic=\(level)")
+        }
+
+        // Sets the log level for the Agent
+        mutating public func setAgentLogLevel(level: Logger.Level) {
+            self.initArgs.append(contentsOf: ["--log-level", level.description])
+        }
+
+        /// Additional kernel arguments.
+        public var kernelArgs: [String]
+        /// Additional arguments passed to the Initial Process / Agent.
+        public var initArgs: [String]
+
+        /// Initializes the kernel commandline using the mix of kernel arguments
+        /// and init arguments.
+        public init(
+            kernelArgs: [String] = kernelDefaults,
+            initArgs: [String] = []
+        ) {
+            self.kernelArgs = kernelArgs
+            self.initArgs = initArgs
+        }
+
+        /// Initializes the kernel commandline to the defaults of Self.kernelDefaults,
+        /// adds a debug and panic flag as instructed, and optionally a set of init
+        /// process flags to supply to vminitd.
+        public init(debug: Bool, panic: Int, initArgs: [String] = []) {
+            var args = Self.kernelDefaults
+            if debug {
+                args.append("debug")
+            }
+            args.append("panic=\(panic)")
+            self.kernelArgs = args
+            self.initArgs = initArgs
+        }
+    }
+
+    /// Path on disk to the kernel binary.
+    public var path: URL
+    /// Platform for the kernel.
+    public var platform: SystemPlatform
+    /// Kernel and init process command line.
+    public var commandLine: Self.CommandLine
+
+    /// Kernel command line arguments.
+    public var kernelArgs: [String] {
+        self.commandLine.kernelArgs
+    }
+
+    /// Init process arguments.
+    public var initArgs: [String] {
+        self.commandLine.initArgs
+    }
+
+    public init(
+        path: URL,
+        platform: SystemPlatform,
+        commandline: Self.CommandLine = CommandLine(debug: false, panic: 0)
+    ) {
+        self.path = path
+        self.platform = platform
+        self.commandLine = commandline
+    }
+}