Add generic system controller and custom controller for R5 to support power-off/reset.

src/main/java/li/cil/oc2/client/gui/RISCVTestScreen.java

@@ -199,7 +199,7 @@ public final class RISCVTestScreen extends Screen {
 
         loadProgramFile(memory, Buildroot.getLinuxImage());
         loadProgramFile(rom, Buildroot.getFirmware());
-        board.installDeviceTree();
+        board.initialize();
 
         runner = new ConsoleRunner(board);
     }

src/main/java/li/cil/oc2/common/tile/ComputerTileEntity.java

@@ -90,6 +90,11 @@ public final class ComputerTileEntity extends TileEntity implements ITickableTil
             blobStorageJobHandle = null;
         }
 
+        if (virtualMachine != null && !virtualMachine.board.isRunning()) {
+            disposeVirtualMachine();
+            return;
+        }
+
         if (runner != null) {
             runner.tick();
             chunk.markDirty();
@@ -213,7 +218,8 @@ public final class ComputerTileEntity extends TileEntity implements ITickableTil
         }
 
         virtualMachine.board.reset();
-        virtualMachine.board.installDeviceTree();
+        virtualMachine.board.initialize();
+        virtualMachine.board.setRunning(true);
         runner = new ConsoleRunner(virtualMachine);
     }