support custom initramfs, build a non-debug kernel by default

`make defconfig debug.config` will bring back the old options

arch/wasm/configs/defconfig

@@ -52,30 +52,6 @@ CONFIG_EXT2_FS=y
 # CONFIG_INOTIFY_USER is not set
 # CONFIG_PROC_FS is not set
 # CONFIG_SYSFS is not set
-CONFIG_SQUASHFS=y
-CONFIG_PRINTK_TIME=y
-CONFIG_PRINTK_CALLER=y
 # CONFIG_DEBUG_MISC is not set
-CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
-CONFIG_FRAME_WARN=2048
-CONFIG_DEBUG_FS=y
-CONFIG_UBSAN=y
-CONFIG_PAGE_EXTENSION=y
-CONFIG_DEBUG_OBJECTS=y
-CONFIG_DEBUG_OBJECTS_FREE=y
-CONFIG_DEBUG_OBJECTS_TIMERS=y
-CONFIG_DEBUG_OBJECTS_WORK=y
-CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
-CONFIG_DEBUG_OBJECTS_PERCPU_COUNTER=y
-CONFIG_DEBUG_STACK_USAGE=y
-CONFIG_SCHED_STACK_END_CHECK=y
-CONFIG_DEBUG_VM=y
-CONFIG_DEBUG_VM_RB=y
-CONFIG_DEBUG_VM_PGFLAGS=y
-CONFIG_DEBUG_PER_CPU_MAPS=y
-CONFIG_PANIC_ON_OOPS=y
-CONFIG_SOFTLOCKUP_DETECTOR=y
-CONFIG_DEBUG_IRQFLAGS=y
-CONFIG_BUG_ON_DATA_CORRUPTION=y
 # CONFIG_RCU_TRACE is not set
 # CONFIG_RUNTIME_TESTING_MENU is not set

tools/wasm/public/index.html

@@ -70,25 +70,10 @@
       </p>
 
       <p>
-        It's only early days for this port, and it doesn't make it all the way
-        through boot yet, but we're getting close, and all the fundamentals are
-        there.
+        We've got a patched version of the Linux kernel and Musl libc running,
+        complete with virtio devices, memory isolation, and multi-core support.
       </p>
 
-      <p>
-        (context switching was particularly painful to implement in such a
-        constrained environment, but I think the solution ended up being quite
-        elegant.)
-      </p>
-
-      <p>All that's left to implement before we can boot BusyBox is:</p>
-      <ul>
-        <li>the ability to load binaries</li>
-        <li>somewhere to load them from (virtio in the browser?)</li>
-        <li>external syscall dispatch</li>
-        <li>and the ability to jump into userspace</li>
-      </ul>
-
       <p>
         If this sounds interesting, you can check out the source at
         <a href="https://github.com/tombl/linux">github.com/tombl/linux</a>
@@ -105,6 +90,8 @@
         <input type="text" name="cmdline" id="cmdline" />
         <label for="memory">Memory (in MiB)</label>
         <input type="number" name="memory" id="memory" />
+        <label for="initcpio">URL to an initramfs</label>
+        <input type="text" name="initcpio" id="initcpio" />
         <button type="submit">Reboot</button>
       </form>
     </details>
@@ -145,11 +132,14 @@
         term.write("Error: not cross origin isolated\n");
       }
 
-      const { cmdline = "no_hash_pointers console=hvc0", memory = 128 } = Object.fromEntries(
-        new URLSearchParams(location.search)
-      );
+      const {
+        cmdline = "",
+        memory = navigator.hardwareConcurrency > 16 ? 256 : 128,
+        initcpio: initcpioPath = "initramfs.cpio",
+      } = Object.fromEntries(new URLSearchParams(location.search));
       document.querySelector("input[name=cmdline]").value = cmdline;
       document.querySelector("input[name=memory]").value = memory;
+      document.querySelector("input[name=initcpio]").value = initcpioPath;
 
       const stdin = new ReadableStream({
         start(controller) {
@@ -170,6 +160,11 @@
         },
       });
 
+      const initcpio = await fetch(initcpioPath).then((res) => res.ok && res.arrayBuffer());
+      if (!initcpio) {
+        term.write(`Failed to fetch initramfs.\n`);
+      }
+
       const machine = new Machine({
         cmdline: cmdline.replace(/\+/g, " "),
         memoryMib: memory,
@@ -178,6 +173,7 @@
           new EntropyDevice(),
           new BlockDevice(new Uint8Array(8 * 1024 * 1024)),
         ],
+        initcpio: new Uint8Array(initcpio),
       });
 
       machine.bootConsole.pipeTo(stdout2);

tools/wasm/run.js

@@ -8,23 +8,29 @@ import {
 import { parseArgs } from "jsr:@std/cli@1/parse-args";
 import { assert } from "./src/util.ts";
 
+const defaultMemory = navigator.hardwareConcurrency > 16 ? 256 : 128;
+
 const args = parseArgs(Deno.args, {
   string: ["cmdline"],
   boolean: ["help"],
   default: {
-    cmdline: "no_hash_pointers console=hvc0",
-    memory: 128,
+    cmdline: "",
+    memory: defaultMemory,
     cpus: navigator.hardwareConcurrency,
+    initcpio: import.meta.url
+      .replace("run.js", "public/initramfs.cpio")
+      .replace("file://", ""),
   },
-  alias: { cmdline: "c", memory: "m", cpus: "j", help: "h" },
+  alias: { cmdline: "c", memory: "m", initcpio: "i", cpus: "j", help: "h" },
 });
 
 if (args.help) {
   console.log(`usage: run.ts [options]
 
 options:
-  -c, --cmdline <string>  Command line arguments to pass to the kernel (default: "no_hash_pointers")
-  -m, --memory <number>   Amount of memory to allocate in MiB (default: 128)
+  -c, --cmdline <string>  Command line arguments to pass to the kernel
+  -m, --memory <number>   Amount of memory to allocate in MiB (default: ${defaultMemory})
+  -i, --initcpio <string> Path to the initramfs to boot
   -j, --cpus <number>     Number of CPUs to use (default: number of CPUs on the machine)
   -h, --help              Show this help message
 `);
@@ -43,6 +49,7 @@ const machine = new Machine({
     new EntropyDevice(),
     new BlockDevice(new Uint8Array(8 * 1024 * 1024)),
   ],
+  initcpio: await Deno.readFile(args.initcpio),
 });
 
 machine.bootConsole.pipeTo(Deno.stderr.writable, { preventClose: true });

tools/wasm/src/index.ts

@@ -2,7 +2,6 @@ import initramfs from "./build/initramfs_data.cpio";
 import sections from "./build/sections.json" with { type: "json" };
 import vmlinuxUrl from "./build/vmlinux.wasm";
 import { type DeviceTreeNode, generate_devicetree } from "./devicetree.ts";
-import init2 from "./init2.cpio";
 import { assert, EventEmitter, get_script_path, unreachable } from "./util.ts";
 import { virtio_imports, VirtioDevice } from "./virtio.ts";
 import { type Imports, type Instance, kernel_imports } from "./wasm.ts";
@@ -17,7 +16,7 @@ const vmlinux_promise = "compileStreaming" in WebAssembly
   ? WebAssembly.compileStreaming(vmlinux_response)
   : vmlinux_response.then((r) => r.arrayBuffer()).then(WebAssembly.compile);
 
-const INIT2_ADDR = 0x200000;
+const INITCPIO_ADDR = 0x200000;
 
 export class Machine extends EventEmitter<{
   halt: void;
@@ -29,6 +28,7 @@ export class Machine extends EventEmitter<{
   #workers: Worker[] = [];
   #memory: WebAssembly.Memory;
   #devices: VirtioDevice[];
+  #initcpio?: ArrayBufferView;
 
   memory: Uint8Array;
   devicetree: DeviceTreeNode;
@@ -42,11 +42,13 @@ export class Machine extends EventEmitter<{
     memoryMib?: number;
     cpus?: number;
     devices: VirtioDevice[];
+    initcpio?: ArrayBufferView;
   }) {
     super();
     this.#boot_console = new TransformStream<Uint8Array, Uint8Array>();
     this.#boot_console_writer = this.#boot_console.writable.getWriter();
     this.#devices = options.devices;
+    this.#initcpio = options.initcpio;
 
     const PAGE_SIZE = 0x10000;
     const BYTES_PER_MIB = 0x100000;
@@ -65,11 +67,9 @@ export class Machine extends EventEmitter<{
       "#size-cells": 1,
       chosen: {
         "rng-seed": crypto.getRandomValues(new Uint8Array(64)),
-        bootargs: options.cmdline ?? "no_hash_pointers",
+        bootargs: `console=hvc0 ${options.cmdline ?? ""}`,
         ncpus: options.cpus ?? navigator.hardwareConcurrency,
         sections,
-        "linux,initrd-start": INIT2_ADDR,
-        "linux,initrd-end": INIT2_ADDR + init2.byteLength,
       },
       aliases: {},
       memory: {
@@ -83,7 +83,20 @@ export class Machine extends EventEmitter<{
       },
     };
 
-    this.memory.set(init2, INIT2_ADDR);
+    if (this.#initcpio) {
+      const chosen = this.devicetree.chosen as DeviceTreeNode;
+      chosen["linux,initrd-start"] = INITCPIO_ADDR;
+      chosen["linux,initrd-end"] = INITCPIO_ADDR + this.#initcpio.byteLength;
+
+      this.memory.set(
+        new Uint8Array(
+          this.#initcpio.buffer,
+          this.#initcpio.byteOffset,
+          this.#initcpio.byteLength,
+        ),
+        INITCPIO_ADDR,
+      );
+    }
 
     for (const [i, dev] of this.#devices.entries()) {
       this.devicetree[`virtio${i}`] = {
@@ -97,10 +110,16 @@ export class Machine extends EventEmitter<{
   }
 
   async boot() {
+    const memory_reservations: { address: number; size: number }[] = [];
+    if (this.#initcpio) {
+      memory_reservations.push({
+        address: INITCPIO_ADDR,
+        size: this.#initcpio.byteLength,
+      });
+    }
+
     const devicetree = generate_devicetree(this.devicetree, {
-      memory_reservations: [
-        { address: INIT2_ADDR, size: init2.byteLength },
-      ],
+      memory_reservations,
     });
     const vmlinux = await vmlinux_promise;
 
@@ -182,10 +201,6 @@ export class Machine extends EventEmitter<{
 
     const instance =
       (await WebAssembly.instantiate(vmlinux, imports)) as Instance;
-    // @ts-expect-error
-    globalThis.instance = instance;
-    // @ts-expect-error
-    globalThis.memory = this.#memory;
     instance.exports.boot();
   }
 }

tools/wasm/src/virtio.ts

@@ -188,12 +188,10 @@ export abstract class VirtioDevice<Config extends object = object> {
   vqs: Virtqueue[] = [];
   enable(vq: number, queue: Virtqueue) {
     this.vqs[vq] = queue;
-    console.log("enable", this.constructor.name, vq, queue.size);
   }
   disable(vq: number) {
     const queue = this.vqs[vq];
     assert(queue);
-    console.log("disable", this.constructor.name, vq);
   }
 
   abstract notify(vq: number): void;