From ca6fc549341d30730247792b87edceacf1613834 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Mon, 8 Aug 2022 11:10:54 -0400
Subject: [PATCH] tweak virtio comments
---
kernel/virtio.h | 2 +-
kernel/virtio_disk.c | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/kernel/virtio.h b/kernel/virtio.h
index 3d85583..96272b4 100644
--- a/kernel/virtio.h
+++ b/kernel/virtio.h
@@ -10,7 +10,7 @@
// virtio mmio control registers, mapped starting at 0x10001000.
// from qemu virtio_mmio.h
#define VIRTIO_MMIO_MAGIC_VALUE 0x000 // 0x74726976
-#define VIRTIO_MMIO_VERSION 0x004 // version; 1 is legacy
+#define VIRTIO_MMIO_VERSION 0x004 // version; should be 2
#define VIRTIO_MMIO_DEVICE_ID 0x008 // device type; 1 is net, 2 is disk
#define VIRTIO_MMIO_VENDOR_ID 0x00c // 0x554d4551
#define VIRTIO_MMIO_DEVICE_FEATURES 0x010
diff --git a/kernel/virtio_disk.c b/kernel/virtio_disk.c
index 249860b..ae6c164 100644
--- a/kernel/virtio_disk.c
+++ b/kernel/virtio_disk.c
@@ -20,20 +20,20 @@
#define R(r) ((volatile uint32 *)(VIRTIO0 + (r)))
static struct disk {
- // the first is a set (not a ring) of DMA descriptors, with which the
+ // a set (not a ring) of DMA descriptors, with which the
// driver tells the device where to read and write individual
// disk operations. there are NUM descriptors.
// most commands consist of a "chain" (a linked list) of a couple of
// these descriptors.
struct virtq_desc *desc;
- // next is a ring in which the driver writes descriptor numbers
+ // a ring in which the driver writes descriptor numbers
// that the driver would like the device to process. it only
// includes the head descriptor of each chain. the ring has
// NUM elements.
struct virtq_avail *avail;
- // finally a ring in which the device writes descriptor numbers that
+ // a ring in which the device writes descriptor numbers that
// the device has finished processing (just the head of each chain).
// there are NUM used ring entries.
struct virtq_used *used;