Rewrite ps2kbproc, rbuf (kernel ring buffer) and pipe read/write, Change to -O0 in kernel code

user/tb/main.c

@@ -120,6 +120,8 @@ void do_mode_interactive(void) {
           linebuf[cursor++] = b;
           uprintf("%c", b);
         }
+      } else {
+        schedrelease();
       }
     }