not better

arch/wasm/kernel/irq.c

@@ -1,5 +1,3 @@
-#define pr_fmt(fmt) "wasm/irq: " fmt
-
 #include <asm/smp.h>
 #include <linux/cpu.h>
 #include <linux/bitops.h>
@@ -82,7 +80,7 @@ void arch_local_irq_restore(unsigned long flags)
 static int wasm_irq_map(struct irq_domain *d, unsigned int irq,
 			irq_hw_number_t hw)
 {
-	pr_info("wasm_irq_map: %d -> %lu\n", irq, hw);
+	pr_info("map irq: %d -> %lu\n", irq, hw);
 
 	irq_set_chip_and_handler(irq, &dummy_irq_chip, handle_percpu_irq);
 

block/bdev.c

@@ -998,7 +998,7 @@ int lookup_bdev(const char *pathname, dev_t *dev)
 	if (!may_open_dev(&path))
 		goto out_path_put;
 
-	pr_info("rdev: %p %d\n", inode, inode->i_rdev);
+	pr_info("rdev: %p %d %x\n", inode, inode->i_rdev, inode->i_mode);
 	*dev = inode->i_rdev;
 	error = 0;
 out_path_put:

drivers/block/virtio_blk.c

@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0-only
-//#define DEBUG
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/blkdev.h>

drivers/virtio/virtio_ring.c

@@ -3,6 +3,7 @@
  *
  *  Copyright 2007 Rusty Russell IBM Corporation
  */
+#define DEBUG
 #define pr_fmt(fmt) "vring: " fmt
 
 #include <linux/virtio.h>
@@ -1386,7 +1387,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 		err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs,
 						    in_sgs, data, gfp);
 		if (err != -ENOMEM) {
-			END_USE(vq);
+			// END_USE(vq);
 			return err;
 		}
 

tools/wasm/Makefile

@@ -18,7 +18,7 @@ _kernel:
 	$(Q)$(MAKE) -C ../.. tools/wasm/src/build/vmlinux.wasm tools/wasm/src/build/sections.json
 
 dist/index.js: _kernel $(shell find src -type f)
-	$(Q)$(ESBUILD) --bundle src/index.ts --outdir=dist --format=esm --splitting --sourcemap --loader:.wasm=file --loader:.squashfs=file
+	$(Q)$(ESBUILD) --bundle src/index.ts --outdir=dist --format=esm --splitting --sourcemap --loader:.wasm=file --loader:.img=file
 
 dist/index.d.ts: _kernel $(shell find src -type f -name '*.ts')
 	$(Q)$(TSC)

tools/wasm/src/disk.img

@@ -0,0 +1 @@
+/home/tom/tmp/linuxwasm/disk.img

tools/wasm/src/env.d.ts

@@ -3,7 +3,7 @@ declare module "*.wasm" {
   export default url;
 }
 
-declare module "*.squashfs" {
+declare module "*.img" {
   const url: string;
   export default url;
 }

tools/wasm/src/index.ts

@@ -162,6 +162,8 @@ export class Machine extends EventEmitter<{
 
     const instance =
       (await WebAssembly.instantiate(vmlinux, imports)) as Instance;
+    // @ts-expect-error
+    globalThis.instance = instance;
     instance.exports.boot();
   }
 }

tools/wasm/src/virtio.ts

@@ -9,10 +9,10 @@ import {
 } from "./bytes.ts";
 import { assert } from "./util.ts";
 import type { Imports } from "./wasm.ts";
-import squashfsUrl from "./root.squashfs";
+import rootfsUrl from "./disk.img";
 
-const squashfs = new Uint8Array(
-  await (await fetch(new URL(squashfsUrl, import.meta.url))).arrayBuffer(),
+const rootfs = new Uint8Array(
+  await (await fetch(new URL(rootfsUrl, import.meta.url))).arrayBuffer(),
 );
 
 const TransportFeatures = {
@@ -121,7 +121,7 @@ class Virtqueue {
     this.desc = FixedArray(VirtqDescriptor, size).get(mem, desc_addr);
   }
 
-  pop() {
+  #pop() {
     let i = this.#advance();
     if (i === null) return null;
     const head = i;
@@ -157,6 +157,11 @@ class Virtqueue {
     return chain;
   }
 
+  *[Symbol.iterator]() {
+    let chain;
+    while (chain = this.#pop()) yield chain;
+  }
+
   #advance() {
     const desc = this.desc[this.avail_idx];
     assert(desc);
@@ -239,7 +244,7 @@ export class BlockDevice extends VirtioDevice<BlockDeviceConfig> {
   constructor() {
     super();
     this.features |= BlockDeviceFeatures.FLUSH | BlockDeviceFeatures.RO;
-    this.config.capacity = BigInt(squashfs.length);
+    this.config.capacity = BigInt(rootfs.length / 512);
   }
 
   override notify(vq: number) {
@@ -248,47 +253,49 @@ export class BlockDevice extends VirtioDevice<BlockDeviceConfig> {
     const queue = this.vqs[vq];
     assert(queue);
 
-    const chain = queue.pop();
-    assert(chain);
-
-    const [header, data, status, trailing] = chain;
-    assert(header && !header.writable, "header must be readonly");
-    assert(
-      header.array.byteLength === BlockDeviceRequest.size,
-      `header size is ${header.array.byteLength}`,
-    );
-    assert(data, "data must exist");
-    assert(status && status.writable, "status must be writable");
-    assert(
-      status.array.byteLength === 1,
-      `status size is ${status.array.byteLength}`,
-    );
-    assert(!trailing, "too many descriptors");
-
-    const request = new BlockDeviceRequest(header.array);
-
-    let n = 0;
-    switch (request.type) {
-      case BlockDeviceRequestType.IN: {
-        assert(data.writable, "data must be writable when IN");
-        const sector = Number(request.sector);
-        const start = sector * 512;
-        const end = start + 512;
-        if (end > squashfs.length) {
-          status.array[0] = BlockDeviceStatus.IOERR;
-        } else {
-          data.array.set(squashfs.slice(start, end));
-          n = 512;
+    for (const chain of queue) {
+      const [header, data, status, trailing] = chain;
+      assert(header && !header.writable, "header must be readonly");
+      assert(
+        header.array.byteLength === BlockDeviceRequest.size,
+        `header size is ${header.array.byteLength}`,
+      );
+      assert(data, "data must exist");
+      assert(status && status.writable, "status must be writable");
+      assert(
+        status.array.byteLength === 1,
+        `status size is ${status.array.byteLength}`,
+      );
+      assert(!trailing, "too many descriptors");
+
+      const request = new BlockDeviceRequest(header.array);
+
+      let n = 0;
+      switch (request.type) {
+        case BlockDeviceRequestType.IN: {
+          assert(data.writable, "data must be writable when IN");
+          const start = Number(request.sector) * 512;
+          let end = start + data.array.byteLength;
+          if (end >= rootfs.length) end = rootfs.length - 1;
+          data.array.set(rootfs.subarray(start, end));
+          n = end - start;
           status.array[0] = BlockDeviceStatus.OK;
+          break;
         }
-        break;
+        default:
+          console.error("unknown request type", request.type);
+          status.array[0] = BlockDeviceStatus.UNSUPP;
       }
-      default:
-        console.error("unknown request type", request.type);
-        status.array[0] = BlockDeviceStatus.UNSUPP;
-    }
 
-    chain.release(n);
+      console.log(
+        request.type,
+        request.sector,
+        status.array[0],
+        btoa(String.fromCharCode(...data.array)),
+      );
+
+      chain.release(n);
+    }
     this.trigger_interrupt("vring");
   }
 }
@@ -304,20 +311,20 @@ export class EntropyDevice extends VirtioDevice<EmptyStruct> {
     const queue = this.vqs[vq];
     assert(queue);
 
-    const chain = queue.pop();
-    assert(chain);
-    let n = 0;
-    for (const { array, writable } of chain) {
-      assert(writable);
+    for (const chain of queue) {
+      let n = 0;
+      for (const { array, writable } of chain) {
+        assert(writable);
 
-      // can't use crypto.getRandomValues on a SharedArrayBuffer
-      const arr = new Uint8Array(array.length);
-      crypto.getRandomValues(arr);
-      array.set(arr);
+        // can't use crypto.getRandomValues on a SharedArrayBuffer
+        const arr = new Uint8Array(array.length);
+        crypto.getRandomValues(arr);
+        array.set(arr);
 
-      n += array.byteLength;
+        n += array.byteLength;
+      }
+      chain.release(n);
     }
-    chain.release(n);
 
     this.trigger_interrupt("vring");
   }
@@ -340,7 +347,10 @@ export function virtio_imports(
     set_features(dev, features) {
       const device = devices[dev];
       assert(device);
-      device.features = features;
+      assert(
+        device.features === features,
+        "the kernel should accept every feature we offer, and no more",
+      );
     },
 
     enable_vring(dev, vq, size, desc_addr) {