diff --git a/kernel/pci/qemu_pci_serial/qemu_pci_serial.c b/kernel/pci/qemu_pci_serial/qemu_pci_serial.c
index e33f651..af20cfc 100644
--- a/kernel/pci/qemu_pci_serial/qemu_pci_serial.c
+++ b/kernel/pci/qemu_pci_serial/qemu_pci_serial.c
@@ -6,6 +6,8 @@
 #include "sysdefs/dev.h"
 #include "util/util.h"
 #include "dev/dev.h"
+#include "cjob/cjob.h"
+#include "proc/proc.h"
 #include "errors.h"
 #include "hshtb.h"
 #include "kprintf.h"
@@ -53,6 +55,11 @@ int32_t qemu_pci_serial_dev_sendb(struct Dev *dev, uint8_t *buffer, size_t len,
   (void)len; (void)pid;
 
   QemuPciSerialDev *qpsd = dev->extra;
+
+  if (qpsd->lockstate != -1 && qpsd->lockstate != (int)pid) {
+    return E_DEVLOCKED;
+  }
+
   _serial_sendb(qpsd->iobase, buffer[0]);
 
   return E_OK;
@@ -62,6 +69,10 @@ int32_t qemu_pci_serial_dev_sendready(struct Dev *dev, uint8_t *buffer, size_t l
   (void)buffer; (void)len; (void)pid;
 
   QemuPciSerialDev *qpsd = dev->extra;
+  
+  if (qpsd->lockstate != -1 && qpsd->lockstate != (int)pid) {
+    return E_DEVLOCKED;
+  }
 
   return _serial_sendready(qpsd->iobase);
 }
@@ -70,16 +81,75 @@ int32_t qemu_pci_serial_dev_recvb(struct Dev *dev, uint8_t *buffer, size_t len,
   (void)buffer; (void)len; (void)pid;
   
   QemuPciSerialDev *qpsd = dev->extra;
+  
+  if (qpsd->lockstate != -1 && qpsd->lockstate != (int)pid) {
+    return E_DEVLOCKED;
+  }
 
   return _serial_recvb(qpsd->iobase);
 }
 
 int32_t qemu_pci_serial_dev_recvready(struct Dev *dev, uint8_t *buffer, size_t len, uint64_t pid) {
-  (void)dev; (void)buffer; (void)len; (void)pid;
+  (void)buffer; (void)len; (void)pid;
+  
+  QemuPciSerialDev *qpsd = dev->extra;
+  
+  if (qpsd->lockstate != -1 && qpsd->lockstate != (int)pid) {
+    return E_DEVLOCKED;
+  }
+
+  return _serial_recvready(qpsd->iobase);
+}
+
+int32_t qemu_pci_serial_dev_lock(struct Dev *dev, uint8_t *buffer, size_t len, uint64_t pid) {
+  (void)buffer; (void)len; (void)pid;
   
   QemuPciSerialDev *qpsd = dev->extra;
 
-  return _serial_recvready(qpsd->iobase);
+  if (qpsd->lockstate == (int)pid) {
+    return E_OK;
+  }
+
+  if (qpsd->lockstate == -1) {
+    qpsd->lockstate = (int)pid;
+    return E_OK;
+  }
+  return E_DEVLOCKED;
+}
+
+int32_t qemu_pci_serial_dev_unlock(struct Dev *dev, uint8_t *buffer, size_t len, uint64_t pid) {
+  (void)buffer; (void)len; (void)pid;
+  
+  QemuPciSerialDev *qpsd = dev->extra;
+
+  if (qpsd->lockstate == (int)pid) {
+    qpsd->lockstate = -1;
+    return E_OK;
+  }
+  return E_DEVNOTYOURLOCK;
+}
+
+void pci_qemu_pci_serial_gc_cjob(void *arg) {
+  Dev *dev = arg;
+
+  QemuPciSerialDev *qpsd;
+
+  spinlock_acquire(&dev->spinlock);
+  qpsd = dev->extra;
+  uint64_t pid = qpsd->lockstate;  
+  spinlock_release(&dev->spinlock);
+
+  Proc *proc = NULL;
+  spinlock_acquire(&PROCS.spinlock);
+  LL_FINDPROP(PROCS.procs, proc, pid, pid);
+  spinlock_release(&PROCS.spinlock);
+
+  if (proc == NULL) {
+    spinlock_acquire(&dev->spinlock);
+    qpsd = dev->extra;
+    qpsd->lockstate = -1;
+    spinlock_release(&dev->spinlock);
+  }
 }
 
 void pci_qemu_pci_serial_init(void) {
@@ -97,6 +167,7 @@ void pci_qemu_pci_serial_init(void) {
 
   QEMU_PCI_SERIAL_DEV._magic = QEMU_PCI_SERIAL_MAGIC;
   QEMU_PCI_SERIAL_DEV.iobase = iobase;
+  QEMU_PCI_SERIAL_DEV.lockstate = -1;
 
   Dev *serialdev = NULL;
   HSHTB_ALLOC(DEVTABLE.devs, ident, "serialdev", serialdev);
@@ -104,8 +175,13 @@ void pci_qemu_pci_serial_init(void) {
   serialdev->fns[1] = &qemu_pci_serial_dev_sendready;
   serialdev->fns[2] = &qemu_pci_serial_dev_recvb;
   serialdev->fns[3] = &qemu_pci_serial_dev_recvready;
+  serialdev->fns[4] = &qemu_pci_serial_dev_lock;
+  serialdev->fns[5] = &qemu_pci_serial_dev_unlock;
   spinlock_init(&serialdev->spinlock);
   serialdev->extra = &QEMU_PCI_SERIAL_DEV;
+
+  cjob_register(&pci_qemu_pci_serial_gc_cjob, serialdev);
+
   _serial_init(QEMU_PCI_SERIAL_DEV.iobase);
 }
 
diff --git a/kernel/pci/qemu_pci_serial/qemu_pci_serial.h b/kernel/pci/qemu_pci_serial/qemu_pci_serial.h
index 1dcb872..765c0c3 100644
--- a/kernel/pci/qemu_pci_serial/qemu_pci_serial.h
+++ b/kernel/pci/qemu_pci_serial/qemu_pci_serial.h
@@ -9,6 +9,7 @@
 typedef struct {
   uint32_t _magic;
   uint16_t iobase;
+  int lockstate;
 } QemuPciSerialDev;
 
 void pci_qemu_pci_serial_init(void);
diff --git a/share/errors.h b/share/errors.h
index 3ce76ae..373eed9 100644
--- a/share/errors.h
+++ b/share/errors.h
@@ -17,6 +17,8 @@
 #define E_SPAWNERROR       -13
 #define E_NOTYET           -14
 #define E_MOUNTERR         -15
+#define E_DEVLOCKED        -16
+#define E_DEVNOTYOURLOCK   -17
 
 #if !defined(__ASSEMBLER__)
 
@@ -38,6 +40,8 @@ static const char *_ERROR_STRINGS[] = {
   "Process spawn error",
   "Data isn't ready yet",
   "File system mount error",
+  "This device is locked",
+  "Device is hasn't been locked by this process",
 };
 
 #define ERRSTRING_INDEX(ioh) ((size_t)((ioh) < 0 ? (ioh) * (-1) : (ioh)))