diff --git a/src/kernel/src/dev/deci.rs b/src/kernel/src/dev/deci.rs
index c233a5f45..18eeff066 100644
--- a/src/kernel/src/dev/deci.rs
+++ b/src/kernel/src/dev/deci.rs
@@ -34,7 +34,7 @@ impl DeviceDriver for Driver {
         dev: &Arc<CharacterDevice>,
         data: &mut UioMut,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
 
@@ -44,7 +44,7 @@ impl DeviceDriver for Driver {
         dev: &Arc<CharacterDevice>,
         data: &mut Uio,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
 }
diff --git a/src/kernel/src/dev/dipsw.rs b/src/kernel/src/dev/dipsw.rs
index 95fbc3208..59beec616 100644
--- a/src/kernel/src/dev/dipsw.rs
+++ b/src/kernel/src/dev/dipsw.rs
@@ -1,25 +1,74 @@
+use thiserror::Error;
+
 use crate::{
     errno::Errno,
-    fs::{CharacterDevice, DeviceDriver, IoCmd},
+    fs::{
+        make_dev, CharacterDevice, DeviceDriver, DriverFlags, IoCmd, MakeDevError, MakeDevFlags,
+        Mode,
+    },
     process::VThread,
+    ucred::{Gid, Uid},
 };
 use std::sync::Arc;
 
 #[derive(Debug)]
 struct Dipsw {}
 
+impl Dipsw {
+    fn new() -> Self {
+        Self {}
+    }
+}
+
 impl DeviceDriver for Dipsw {
     #[allow(unused_variables)]
     fn ioctl(
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        td: &VThread,
+        td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
+        let td = td.unwrap();
+
         if !td.cred().is_system() {
             todo!()
         } else {
-            todo!()
+            match cmd {
+                // TODO: properly implement this
+                IoCmd::DIPSWCHECK2(val) => *val = false as i32,
+                _ => todo!(),
+            }
         }
+
+        Ok(())
     }
 }
+
+pub struct DipswManager {
+    dipsw: Arc<CharacterDevice>,
+}
+
+impl DipswManager {
+    pub fn new() -> Result<Arc<Self>, DipswInitError> {
+        let dipsw = make_dev(
+            Dipsw::new(),
+            DriverFlags::from_bits_retain(0x80000004),
+            0,
+            "dipsw",
+            Uid::ROOT,
+            Gid::ROOT,
+            Mode::new(0o644).unwrap(),
+            None,
+            MakeDevFlags::MAKEDEV_ETERNAL,
+        )?;
+
+        Ok(Arc::new(Self { dipsw }))
+    }
+}
+
+/// Represents an error when [`TtyManager`] fails to initialize.
+#[derive(Debug, Error)]
+pub enum DipswInitError {
+    #[error("cannot create dipsw device")]
+    CreateConsoleFailed(#[from] MakeDevError),
+}
diff --git a/src/kernel/src/dev/dmem.rs b/src/kernel/src/dev/dmem.rs
index 6e997fc34..95caf5dd0 100644
--- a/src/kernel/src/dev/dmem.rs
+++ b/src/kernel/src/dev/dmem.rs
@@ -56,8 +56,10 @@ impl DeviceDriver for Dmem {
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        td: &VThread,
+        td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
+        let td = td.unwrap();
+
         let cred = td.cred();
 
         if cred.is_unk1() || cred.is_unk2() {
diff --git a/src/kernel/src/dev/gc.rs b/src/kernel/src/dev/gc.rs
index 7d11d1ed9..83ed84c80 100644
--- a/src/kernel/src/dev/gc.rs
+++ b/src/kernel/src/dev/gc.rs
@@ -25,7 +25,7 @@ impl DeviceDriver for Gc {
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        td: &VThread,
+        td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
diff --git a/src/kernel/src/dev/hid.rs b/src/kernel/src/dev/hid.rs
index 213d803ff..4be4db498 100644
--- a/src/kernel/src/dev/hid.rs
+++ b/src/kernel/src/dev/hid.rs
@@ -15,7 +15,7 @@ impl DeviceDriver for Hid {
         dev: &Arc<CharacterDevice>,
         data: &mut UioMut,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
 
@@ -24,7 +24,7 @@ impl DeviceDriver for Hid {
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        td: &VThread,
+        td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
diff --git a/src/kernel/src/dev/random.rs b/src/kernel/src/dev/random.rs
index 75a0e3214..45e33fdbb 100644
--- a/src/kernel/src/dev/random.rs
+++ b/src/kernel/src/dev/random.rs
@@ -15,7 +15,7 @@ impl DeviceDriver for Random {
         dev: &Arc<CharacterDevice>,
         data: &mut UioMut,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
 
@@ -25,7 +25,7 @@ impl DeviceDriver for Random {
         dev: &Arc<CharacterDevice>,
         data: &mut Uio,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
 
@@ -33,7 +33,7 @@ impl DeviceDriver for Random {
         &self,
         _: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        _: &VThread,
+        _: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
         match cmd {
             IoCmd::FIOASYNC(_) | IoCmd::FIONBIO(_) => Ok(()),
diff --git a/src/kernel/src/dev/rng.rs b/src/kernel/src/dev/rng.rs
index e91d7007f..14bf1927a 100644
--- a/src/kernel/src/dev/rng.rs
+++ b/src/kernel/src/dev/rng.rs
@@ -13,7 +13,7 @@ impl DeviceDriver for Rng {
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        _: &VThread,
+        _: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
         match cmd {
             IoCmd::RNG1 => todo!(),
diff --git a/src/kernel/src/dev/sbl_srv.rs b/src/kernel/src/dev/sbl_srv.rs
index d1ae2f21b..27f1f775f 100644
--- a/src/kernel/src/dev/sbl_srv.rs
+++ b/src/kernel/src/dev/sbl_srv.rs
@@ -14,7 +14,7 @@ impl DeviceDriver for SblSrv {
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        td: &VThread,
+        td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
diff --git a/src/kernel/src/dev/ttyconsole.rs b/src/kernel/src/dev/ttyconsole.rs
index 6f33f5fb9..b0ecb0317 100644
--- a/src/kernel/src/dev/ttyconsole.rs
+++ b/src/kernel/src/dev/ttyconsole.rs
@@ -1,22 +1,27 @@
+use crate::errno::EPERM;
 use crate::fs::{
     make_dev, CharacterDevice, DeviceDriver, DriverFlags, IoCmd, MakeDevError, MakeDevFlags, Mode,
     OpenFlags, Uio, UioMut,
 };
 use crate::ucred::{Gid, Uid};
 use crate::{errno::Errno, process::VThread};
+use macros::Errno;
 use std::sync::Arc;
 use thiserror::Error;
 
 #[derive(Debug)]
-pub struct TtyConsole {}
+pub struct TtyConsole {
+    tty: Tty,
+}
 
 impl TtyConsole {
     pub fn new() -> Self {
-        Self {}
+        Self { tty: Tty::new() }
     }
 }
 
 impl DeviceDriver for TtyConsole {
+    #[allow(unused_variables)] // TODO: remove when implementing
     fn open(
         &self,
         dev: &Arc<CharacterDevice>,
@@ -33,7 +38,7 @@ impl DeviceDriver for TtyConsole {
         dev: &Arc<CharacterDevice>,
         data: &mut UioMut,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
 
@@ -43,18 +48,53 @@ impl DeviceDriver for TtyConsole {
         dev: &Arc<CharacterDevice>,
         data: &mut Uio,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         todo!()
     }
 
     #[allow(unused_variables)] // TODO: remove when implementing
+    /// See `ttydev_ioctl` on the PS4 for a reference.
     fn ioctl(
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        td: &VThread,
+        td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
-        todo!()
+        // TODO: implement tty_wait_background
+
+        match cmd {
+            IoCmd::TIOCSCTTY => self.tty.ioctl(cmd, td)?,
+            _ => todo!(),
+        }
+
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+struct Tty {}
+
+impl Tty {
+    fn new() -> Self {
+        Self {}
+    }
+
+    /// See `tty_ioctl` on the PS4 for a reference.
+    fn ioctl(&self, cmd: IoCmd, td: Option<&VThread>) -> Result<(), TtyIoctlError> {
+        // TODO: implement ttydevsw_ioctl
+
+        self.generic_ioctl(cmd, td)
+    }
+
+    /// See `tty_ioctl` on the PS4 for a reference.
+    fn generic_ioctl(&self, cmd: IoCmd, td: Option<&VThread>) -> Result<(), TtyIoctlError> {
+        // TODO: implement ttydevsw_ioctl
+
+        match cmd {
+            // TODO: implement this properly
+            IoCmd::TIOCSCTTY => return Ok(()),
+            _ => todo!(),
+        }
     }
 }
 
@@ -66,7 +106,7 @@ pub struct TtyManager {
 }
 
 impl TtyManager {
-    pub fn new() -> Result<Arc<Self>, TtyInitError> {
+    pub fn new() -> Result<Arc<Self>, TtyManagerInitError> {
         // Create /dev/console.
 
         let console = make_dev(
@@ -87,7 +127,15 @@ impl TtyManager {
 
 /// Represents an error when [`TtyManager`] fails to initialize.
 #[derive(Debug, Error)]
-pub enum TtyInitError {
+pub enum TtyManagerInitError {
     #[error("cannot create console device")]
     CreateConsoleFailed(#[from] MakeDevError),
 }
+
+/// Represents an error when [`Tty::ioctl`] fails to initialize.
+#[derive(Debug, Error, Errno)]
+pub enum TtyIoctlError {
+    #[error("process is not leader")]
+    #[errno(EPERM)]
+    ProcessNotLeader,
+}
diff --git a/src/kernel/src/fs/dev/cdev.rs b/src/kernel/src/fs/dev/cdev.rs
index 102ae6861..96419661b 100644
--- a/src/kernel/src/fs/dev/cdev.rs
+++ b/src/kernel/src/fs/dev/cdev.rs
@@ -137,7 +137,13 @@ impl FileBackend for CharacterDevice {
         cmd: IoCmd,
         td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
-        todo!()
+        match cmd {
+            IoCmd::FIODTYPE(_) => todo!(),
+            IoCmd::FIODGNAME(_) => todo!(),
+            _ => self.driver.ioctl(self, cmd, td)?,
+        }
+
+        Ok(())
     }
 
     #[allow(unused_variables)] // TODO: remove when implementing
@@ -179,6 +185,13 @@ bitflags! {
     }
 }
 
+#[repr(C)]
+#[derive(Debug)]
+pub struct FioDeviceGetNameArg {
+    len: i32,
+    buf: *mut u8,
+}
+
 /// An implementation of the `cdevsw` structure.
 pub trait DeviceDriver: Debug + Sync + Send + 'static {
     #[allow(unused_variables)]
@@ -198,7 +211,7 @@ pub trait DeviceDriver: Debug + Sync + Send + 'static {
         dev: &Arc<CharacterDevice>,
         data: &mut UioMut,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         Err(Box::new(DefaultDeviceError::ReadNotSupported))
     }
 
@@ -208,7 +221,7 @@ pub trait DeviceDriver: Debug + Sync + Send + 'static {
         dev: &Arc<CharacterDevice>,
         data: &mut Uio,
         td: Option<&VThread>,
-    ) -> Result<usize, Box<dyn Errno>> {
+    ) -> Result<(), Box<dyn Errno>> {
         Err(Box::new(DefaultDeviceError::WriteNotSupported))
     }
 
@@ -217,7 +230,7 @@ pub trait DeviceDriver: Debug + Sync + Send + 'static {
         &self,
         dev: &Arc<CharacterDevice>,
         cmd: IoCmd,
-        td: &VThread,
+        td: Option<&VThread>,
     ) -> Result<(), Box<dyn Errno>> {
         Err(Box::new(DefaultDeviceError::IoctlNotSupported))
     }
diff --git a/src/kernel/src/fs/dev/vnode.rs b/src/kernel/src/fs/dev/vnode.rs
index 0da472d89..ce0748469 100644
--- a/src/kernel/src/fs/dev/vnode.rs
+++ b/src/kernel/src/fs/dev/vnode.rs
@@ -94,7 +94,13 @@ impl crate::fs::VnodeBackend for VnodeBackend {
             _ => 0,
         };
 
-        todo!()
+        Ok(VnodeAttrs {
+            uid: *uid,
+            gid: *gid,
+            mode: *mode,
+            size,
+            fsid: u32::MAX,
+        })
     }
 
     fn ioctl(
@@ -162,9 +168,9 @@ impl crate::fs::VnodeBackend for VnodeBackend {
         }
     }
 
-    fn revoke(&self, vn: &Arc<Vnode>, flags: RevokeFlags) -> Result<(), Box<dyn Errno>> {
+    fn revoke(&self, vn: &Arc<Vnode>, _flags: RevokeFlags) -> Result<(), Box<dyn Errno>> {
         // TODO: Implement this.
-        todo!()
+        Ok(())
     }
 
     fn read(
diff --git a/src/kernel/src/fs/ioctl.rs b/src/kernel/src/fs/ioctl.rs
index b606e2e98..dbabdef1a 100644
--- a/src/kernel/src/fs/ioctl.rs
+++ b/src/kernel/src/fs/ioctl.rs
@@ -1,3 +1,4 @@
+use super::FioDeviceGetNameArg;
 use crate::dev::{DmemAllocate, DmemAvailable, DmemQuery, PrtAperture};
 use crate::dmem::{BlockpoolExpandArgs, BlockpoolStats};
 use crate::errno::ENOTTY;
@@ -19,7 +20,7 @@ macro_rules! commands {
                 )*
             }
         ) => {
-            /// A wrapper type for an ioctl command.
+            /// A wrapper type for an ioctl command and its data.
             /// FreeBSD uses an u_long, but masks off the top 4 bytes in kern_ioctl, so we can use an u32.
             #[derive(Debug)]
             #[non_exhaustive]
@@ -93,7 +94,7 @@ commands! {
         BPOOLSTATS(&mut BlockpoolStats) = 0x4010A802,
 
         /// Get media size in bytes.
-        DIOCGMEDIASIZE(&i64) = 0x40086418,
+        DIOCGMEDIASIZE(&mut i64) = 0x40086418,
 
         /// sceKernelInitializeDipsw
         DIPSWINIT = 0x20008800,
@@ -125,10 +126,22 @@ commands! {
         FIOCLEX = 0x20006601,
         /// Remove close on exec on fd.
         FIONCLEX = 0x20006602,
+        /// Get # bytes to read
+        FIONREAD(&mut i32) = 0x4004667f,
         /// Set/clear non-blocking I/O.
-        FIONBIO(&i32) = 0x8004667d,
+        FIONBIO(&i32) = 0x8004667e,
         /// Set/clear async I/O.
-        FIOASYNC(&i32) = 0x8004667e,
+        FIOASYNC(&i32) = 0x8004667d,
+        /// Set owner
+        FIOSETOWN(&i32) = 0x8004667c,
+        /// Get owner
+        FIOGETOWN(&mut i32) = 0x4004667b,
+        /// get d_flags type part
+        FIODTYPE(&mut i32) = 0x4004667a,
+        /// Get start blk #
+        FIOGETLBA(&mut i32) = 0x40046679,
+        /// Get dev. name
+        FIODGNAME(&FioDeviceGetNameArg) = 0x80106678,
         /// Seek data.
         FIOSEEKDATA(&mut i64) = 0xC0086661,
         /// Seek hole.
@@ -141,7 +154,6 @@ commands! {
 
         /// Become controlling terminal.
         TIOCSCTTY = 0x20007461,
-
     }
 }
 
diff --git a/src/kernel/src/main.rs b/src/kernel/src/main.rs
index 325235cef..8c37651ad 100644
--- a/src/kernel/src/main.rs
+++ b/src/kernel/src/main.rs
@@ -1,6 +1,6 @@
 use crate::arch::MachDep;
 use crate::budget::{Budget, BudgetManager, ProcType};
-use crate::dev::{DebugManager, TtyManager};
+use crate::dev::{DebugManager, DipswManager, TtyManager};
 use crate::dmem::DmemManager;
 use crate::ee::native::NativeEngine;
 use crate::ee::EntryArg;
@@ -22,7 +22,7 @@ use crate::time::TimeManager;
 use crate::ucred::{AuthAttrs, AuthCaps, AuthInfo, AuthPaid, Gid, Ucred, Uid};
 use crate::umtx::UmtxManager;
 use clap::Parser;
-use dev::{DebugManagerInitError, TtyInitError};
+use dev::{DebugManagerInitError, DipswInitError, TtyManagerInitError};
 use dmem::DmemManagerInitError;
 use llt::{OsThread, SpawnError};
 use macros::vpath;
@@ -190,6 +190,7 @@ fn run() -> Result<(), KernelError> {
     ));
 
     // Initialize foundations.
+    #[allow(unused_variables)] // TODO: Remove this when someone uses hv.
     let hv = Hypervisor::new()?;
     let mut syscalls = Syscalls::new();
     let fs = Fs::new(args.system, &cred, &mut syscalls)?;
@@ -344,6 +345,8 @@ fn run() -> Result<(), KernelError> {
     // Initialize TTY system.
     #[allow(unused_variables)] // TODO: Remove this when someone uses tty.
     let tty = TtyManager::new()?;
+    #[allow(unused_variables)] // TODO: Remove this when someone uses dipsw.
+    let dipsw = DipswManager::new()?;
 
     // Initialize kernel components.
     #[allow(unused_variables)] // TODO: Remove this when someone uses debug.
@@ -609,7 +612,10 @@ enum KernelError {
     MountFailed(VPathBuf, #[source] MountError),
 
     #[error("tty initialization failed")]
-    TtyInitFailed(#[from] TtyInitError),
+    TtyInitFailed(#[from] TtyManagerInitError),
+
+    #[error("dipsw initialization failed")]
+    DipswInitFailed(#[from] DipswInitError),
 
     #[error("debug manager initialization failed")]
     DebugManagerInitFailed(#[from] DebugManagerInitError),
diff --git a/src/kernel/src/process/group.rs b/src/kernel/src/process/group.rs
index 1d49626d9..d8f9eb854 100644
--- a/src/kernel/src/process/group.rs
+++ b/src/kernel/src/process/group.rs
@@ -1,19 +1,30 @@
 use super::VSession;
+use gmtx::{Gutex, GutexGroup, GutexReadGuard, GutexWriteGuard};
 use std::num::NonZeroI32;
+use std::sync::Arc;
 
 /// An implementation of `pgrp` struct.
 #[derive(Debug)]
 pub struct VProcGroup {
-    id: NonZeroI32,    // pg_id
-    session: VSession, // pg_session
+    id: NonZeroI32,                // pg_id
+    session: Gutex<Arc<VSession>>, // pg_session
 }
 
 impl VProcGroup {
-    pub fn new(id: NonZeroI32, session: VSession) -> Self {
-        Self { id, session }
+    pub fn new(id: NonZeroI32, session: Arc<VSession>) -> Arc<Self> {
+        let gg = GutexGroup::new();
+
+        Arc::new(Self {
+            id,
+            session: gg.spawn(session),
+        })
+    }
+
+    pub fn session(&self) -> GutexReadGuard<'_, Arc<VSession>> {
+        self.session.read()
     }
 
-    pub fn session_mut(&mut self) -> &mut VSession {
-        &mut self.session
+    pub fn session_mut(&self) -> GutexWriteGuard<'_, Arc<VSession>> {
+        self.session.write()
     }
 }
diff --git a/src/kernel/src/process/mod.rs b/src/kernel/src/process/mod.rs
index 0dd83e4fc..cb172d505 100644
--- a/src/kernel/src/process/mod.rs
+++ b/src/kernel/src/process/mod.rs
@@ -55,18 +55,18 @@ mod thread;
 /// once we have migrated the PS4 code to run inside a virtual machine.
 #[derive(Debug)]
 pub struct VProc {
-    id: NonZeroI32,                    // p_pid
-    threads: Gutex<Vec<Arc<VThread>>>, // p_threads
-    cred: Ucred,                       // p_ucred
-    group: Gutex<Option<VProcGroup>>,  // p_pgrp
-    abi: OnceLock<ProcAbi>,            // p_sysent
-    vm: Arc<Vm>,                       // p_vmspace
-    sigacts: Gutex<SignalActs>,        // p_sigacts
-    files: Arc<FileDesc>,              // p_fd
-    system_path: String,               // p_randomized_path
-    limits: Limits,                    // p_limit
-    comm: Gutex<Option<String>>,       // p_comm
-    bin: Gutex<Option<Binaries>>,      // p_dynlib?
+    id: NonZeroI32,                        // p_pid
+    threads: Gutex<Vec<Arc<VThread>>>,     // p_threads
+    cred: Ucred,                           // p_ucred
+    group: Gutex<Option<Arc<VProcGroup>>>, // p_pgrp
+    abi: OnceLock<ProcAbi>,                // p_sysent
+    vm: Arc<Vm>,                           // p_vmspace
+    sigacts: Gutex<SignalActs>,            // p_sigacts
+    files: Arc<FileDesc>,                  // p_fd
+    system_path: String,                   // p_randomized_path
+    limits: Limits,                        // p_limit
+    comm: Gutex<Option<String>>,           // p_comm
+    bin: Gutex<Option<Binaries>>,          // p_dynlib?
     objects: Gutex<Idt<Arc<dyn Any + Send + Sync>>>,
     budget_id: usize,
     budget_ptype: ProcType,
@@ -261,7 +261,11 @@ impl VProc {
 
     fn sys_sigprocmask(self: &Arc<Self>, td: &VThread, i: &SysIn) -> Result<SysOut, SysErr> {
         // Get arguments.
-        let how: i32 = i.args[0].try_into().unwrap();
+        let how: How = {
+            let how: i32 = i.args[0].try_into().unwrap();
+            how.try_into()?
+        };
+
         let set: *const SignalSet = i.args[1].into();
         let oset: *mut SignalSet = i.args[2].into();
 
@@ -280,7 +284,7 @@ impl VProc {
         // Update the mask.
         if let Some(mut set) = set {
             match how {
-                SIG_BLOCK => {
+                How::Block => {
                     // Remove uncatchable signals.
                     set.remove(SIGKILL);
                     set.remove(SIGSTOP);
@@ -288,13 +292,13 @@ impl VProc {
                     // Update mask.
                     *mask |= set;
                 }
-                SIG_UNBLOCK => {
+                How::Unblock => {
                     // Update mask.
                     *mask &= !set;
 
                     // TODO: Invoke signotify at the end.
                 }
-                SIG_SETMASK => {
+                How::SetMask => {
                     // Remove uncatchable signals.
                     set.remove(SIGKILL);
                     set.remove(SIGSTOP);
@@ -304,7 +308,6 @@ impl VProc {
 
                     // TODO: Invoke signotify at the end.
                 }
-                _ => return Err(SysErr::Raw(EINVAL)),
             }
 
             // TODO: Check if we need to invoke reschedule_signals.
@@ -796,6 +799,28 @@ impl VProc {
     }
 }
 
+#[derive(Debug)]
+enum How {
+    Block,
+    Unblock,
+    SetMask,
+}
+
+impl TryFrom<i32> for How {
+    type Error = SysErr;
+
+    fn try_from(value: i32) -> Result<Self, Self::Error> {
+        let how = match value {
+            SIG_BLOCK => How::Block,
+            SIG_UNBLOCK => How::Unblock,
+            SIG_SETMASK => How::SetMask,
+            _ => return Err(SysErr::Raw(EINVAL)),
+        };
+
+        Ok(how)
+    }
+}
+
 #[repr(C)]
 struct ThrParam {
     start_func: fn(usize),
diff --git a/src/kernel/src/process/session.rs b/src/kernel/src/process/session.rs
index 63cceb670..810fa7ab0 100644
--- a/src/kernel/src/process/session.rs
+++ b/src/kernel/src/process/session.rs
@@ -1,18 +1,26 @@
 use std::num::NonZeroI32;
+use std::sync::Arc;
+
+use gmtx::{Gutex, GutexGroup};
 
 /// An implementation of `session` structure.
 #[derive(Debug)]
 pub struct VSession {
-    id: NonZeroI32, // s_sid
-    login: String,  // s_login
+    id: NonZeroI32,       // s_sid
+    login: Gutex<String>, // s_login
 }
 
 impl VSession {
-    pub fn new(id: NonZeroI32, login: String) -> Self {
-        Self { id, login }
+    pub fn new(id: NonZeroI32, login: String) -> Arc<Self> {
+        let gg = GutexGroup::new();
+
+        Arc::new(Self {
+            id,
+            login: gg.spawn(login),
+        })
     }
 
-    pub fn set_login<V: Into<String>>(&mut self, v: V) {
-        self.login = v.into();
+    pub fn set_login<V: Into<String>>(&self, v: V) {
+        *self.login.write() = v.into();
     }
 }