Better virtual file system, keyboard through MMIO&VirtIO

crates/shared/src/fs.rs

@@ -1,9 +1,16 @@
+#[derive(Debug)]
 pub struct File {
     fd: u64,
 }
 
 impl File {
+    /// # Safety
+    /// The file descriptor must be valid
     pub unsafe fn new(fd: u64) -> Self {
         Self { fd }
     }
+
+    pub fn as_fd(&self) -> u64 {
+        self.fd
+    }
 }