Finish virtio

risc_v/ch9/src/block.rs

@@ -256,6 +256,9 @@ pub fn block_op(dev: usize, buffer: *mut u8, size: u32, offset: u64, write: bool
 				return;
 			}
 			let sector = offset / 512;
+			// TODO: Before we get here, we are NOT allowed to schedule a read or
+			// write OUTSIDE of the disk's size. So, we can read capacity from
+			// the configuration space to ensure we stay within bounds.
 			let blk_request_size = size_of::<Request>();
 			let blk_request = kmalloc(blk_request_size) as *mut Request;
 			let desc = Descriptor { addr:  &(*blk_request).header as *const Header as u64,

risc_v/ch9/src/lib.rs

@@ -209,6 +209,7 @@ pub mod kmem;
 pub mod page;
 pub mod plic;
 pub mod process;
+pub mod rng;
 pub mod sched;
 pub mod syscall;
 pub mod trap;

risc_v/ch9/src/virtio.rs

@@ -4,6 +4,7 @@
 // 10 March 2020
 
 use crate::{block, block::setup_block_device, page::PAGE_SIZE};
+use crate::rng::setup_entropy_device;
 use core::mem::size_of;
 
 // Flags
@@ -24,6 +25,12 @@ pub const VIRTIO_USED_F_NO_NOTIFY: u16 = 1;
 pub const VIRTIO_RING_SIZE: usize = 1 << 7;
 
 // VirtIO structures
+
+// The descriptor holds the data that we need to send to 
+// the device. The address is a physical address and NOT
+// a virtual address. The len is in bytes and the flags are
+// specified above. Any descriptor can be chained, hence the
+// next field, but only if the F_NEXT flag is specified.
 #[repr(C)]
 pub struct Descriptor {
 	pub addr:  u64,
@@ -64,6 +71,8 @@ pub struct Queue {
 	pub used:     Used,
 }
 
+// The MMIO transport is "legacy" in QEMU, so these registers represent
+// the legacy interface.
 #[repr(usize)]
 pub enum MmioOffsets {
 	MagicValue = 0x000,
@@ -280,10 +289,6 @@ pub fn probe() {
 	}
 }
 
-pub fn setup_entropy_device(_ptr: *mut u32) -> bool {
-	false
-}
-
 pub fn setup_network_device(_ptr: *mut u32) -> bool {
 	false
 }