diff --git a/Makefile b/Makefile
index 11eec56..3309c5b 100644
--- a/Makefile
+++ b/Makefile
@@ -91,7 +91,8 @@ initrd:
 		-Z build-std=core,alloc,compiler_builtins \
 		$(CARGO_COMMON_OPTS)
 	cp target/$(ARCH)-osdev5/$(PROFILE)/init $(O)
-	cd $(O) && tar cf initrd.img init
+	echo This is a test file >$(O)/test.txt
+	cd $(O) && tar cf initrd.img init test.txt
 ifeq ($(MACH),orangepi3)
 	$(MKIMAGE) \
 		-A arm64 \
diff --git a/error/src/lib.rs b/error/src/lib.rs
index 0d65793..0792c9e 100644
--- a/error/src/lib.rs
+++ b/error/src/lib.rs
@@ -11,4 +11,6 @@ pub enum Errno {
     AlreadyExists,
     NotImplemented,
     TimedOut,
+    EndOfFile,
+    Interrupt
 }
diff --git a/fs/memfs/src/dir.rs b/fs/memfs/src/dir.rs
index 8756735..4bb4605 100644
--- a/fs/memfs/src/dir.rs
+++ b/fs/memfs/src/dir.rs
@@ -1,4 +1,5 @@
-use vfs::{VnodeImpl, VnodeKind, VnodeRef};
+use vfs::{VnodeImpl, VnodeKind, VnodeRef, Vnode};
+use alloc::boxed::Box;
 use error::Errno;
 
 pub struct DirInode;
@@ -7,14 +8,19 @@ impl VnodeImpl for DirInode {
     fn create(
         &mut self,
         _parent: VnodeRef,
-        _name: &str,
-        _kind: VnodeKind,
+        name: &str,
+        kind: VnodeKind,
     ) -> Result<VnodeRef, Errno> {
-        todo!()
+        let vnode = Vnode::new(name, kind, Vnode::SEEKABLE);
+        match kind {
+            VnodeKind::Directory => vnode.set_data(Box::new(DirInode {})),
+            _ => todo!()
+        }
+        Ok(vnode)
     }
 
     fn lookup(&mut self, _parent: VnodeRef, _name: &str) -> Result<VnodeRef, Errno> {
-        panic!()
+        Err(Errno::DoesNotExist)
     }
 
     fn remove(&mut self, _parent: VnodeRef, _name: &str) -> Result<(), Errno> {
diff --git a/fs/memfs/src/lib.rs b/fs/memfs/src/lib.rs
index 4905c4b..3f3388d 100644
--- a/fs/memfs/src/lib.rs
+++ b/fs/memfs/src/lib.rs
@@ -64,6 +64,8 @@ impl<A: BlockAllocator + Copy + 'static> Ramfs<A> {
         match kind {
             VnodeKind::Directory => node.set_data(Box::new(DirInode {})),
             VnodeKind::Regular => {}
+            VnodeKind::Char => todo!(),
+            VnodeKind::Block => todo!(),
         };
         node
     }
@@ -176,9 +178,9 @@ mod tests {
         let root = fs.root().unwrap();
         let ioctx = Ioctx::new(root.clone());
 
-        assert!(Rc::ptr_eq(&ioctx.find(None, "/").unwrap(), &root));
+        assert!(Rc::ptr_eq(&ioctx.find(None, "/", true).unwrap(), &root));
 
-        let node = ioctx.find(None, "/test1.txt").unwrap();
+        let node = ioctx.find(None, "/test1.txt", true).unwrap();
         let mut file = node.open().unwrap();
         let mut buf = [0u8; 1024];
 
diff --git a/fs/vfs/src/char.rs b/fs/vfs/src/char.rs
new file mode 100644
index 0000000..09fd7ff
--- /dev/null
+++ b/fs/vfs/src/char.rs
@@ -0,0 +1,70 @@
+use crate::{VnodeImpl, VnodeKind, VnodeRef};
+use error::Errno;
+
+/// Generic character device trait
+pub trait CharDevice {
+    /// Performs a read from the device into [data] buffer.
+    ///
+    /// If no data is available and `blocking` is set, will ask
+    /// the OS to suspend the calling thread until data arrives.
+    /// Otherwise, will immediately return an error.
+    fn read(&self, blocking: bool, data: &mut [u8]) -> Result<usize, Errno>;
+    /// Performs a write to the device from [data] buffer.
+    ///
+    /// If the device cannot (at the moment) accept data and
+    /// `blocking` is set, will block until it's available. Otherwise,
+    /// will immediately return an error.
+    fn write(&self, blocking: bool, data: &[u8]) -> Result<usize, Errno>;
+}
+
+/// Wrapper struct to attach [VnodeImpl] implementation
+/// to [CharDevice]s
+pub struct CharDeviceWrapper {
+    device: &'static dyn CharDevice,
+}
+
+impl VnodeImpl for CharDeviceWrapper {
+    fn create(&mut self, _at: VnodeRef, _name: &str, _kind: VnodeKind) -> Result<VnodeRef, Errno> {
+        panic!();
+    }
+
+    fn remove(&mut self, _at: VnodeRef, _name: &str) -> Result<(), Errno> {
+        panic!();
+    }
+
+    fn lookup(&mut self, _at: VnodeRef, _name: &str) -> Result<VnodeRef, Errno> {
+        panic!();
+    }
+
+    fn open(&mut self, _node: VnodeRef) -> Result<usize, Errno> {
+        Ok(0)
+    }
+
+    fn close(&mut self, _node: VnodeRef) -> Result<(), Errno> {
+        Ok(())
+    }
+
+    fn read(&mut self, _node: VnodeRef, _pos: usize, data: &mut [u8]) -> Result<usize, Errno> {
+        self.device.read(true, data)
+    }
+
+    fn write(&mut self, _node: VnodeRef, _pos: usize, data: &[u8]) -> Result<usize, Errno> {
+        self.device.write(true, data)
+    }
+
+    fn truncate(&mut self, _node: VnodeRef, _size: usize) -> Result<(), Errno> {
+        panic!();
+    }
+
+    fn size(&mut self, _node: VnodeRef) -> Result<usize, Errno> {
+        panic!();
+    }
+}
+
+impl CharDeviceWrapper {
+    /// Creates a wrapper for static [CharDevice] trait object to
+    /// auto-implement [VnodeImpl] trait for the device
+    pub const fn new(device: &'static dyn CharDevice) -> Self {
+        Self { device }
+    }
+}
diff --git a/fs/vfs/src/file.rs b/fs/vfs/src/file.rs
index 6531e1a..8ddb929 100644
--- a/fs/vfs/src/file.rs
+++ b/fs/vfs/src/file.rs
@@ -1,4 +1,4 @@
-use crate::VnodeRef;
+use crate::{VnodeRef, VnodeKind};
 use core::cmp::min;
 use error::Errno;
 use libcommon::{Read, Seek, SeekDir, Write};
@@ -25,7 +25,9 @@ impl Read for File {
         match &mut self.inner {
             FileInner::Normal(inner) => {
                 let count = inner.vnode.read(inner.pos, data)?;
-                inner.pos += count;
+                if inner.vnode.kind() != VnodeKind::Char {
+                    inner.pos += count;
+                }
                 Ok(count)
             }
             _ => unimplemented!(),
@@ -38,7 +40,9 @@ impl Write for File {
         match &mut self.inner {
             FileInner::Normal(inner) => {
                 let count = inner.vnode.write(inner.pos, data)?;
-                inner.pos += count;
+                if inner.vnode.kind() != VnodeKind::Char {
+                    inner.pos += count;
+                }
                 Ok(count)
             }
             _ => unimplemented!(),
@@ -111,6 +115,8 @@ mod tests {
         }
 
         fn read(&mut self, _node: VnodeRef, pos: usize, data: &mut [u8]) -> Result<usize, Errno> {
+            #[cfg(test)]
+            println!("read {}", pos);
             let len = 123;
             if pos >= len {
                 return Ok(0);
diff --git a/fs/vfs/src/ioctx.rs b/fs/vfs/src/ioctx.rs
index f80a61d..f3d4e97 100644
--- a/fs/vfs/src/ioctx.rs
+++ b/fs/vfs/src/ioctx.rs
@@ -1,4 +1,4 @@
-use crate::{FileMode, VnodeRef};
+use crate::{FileMode, VnodeRef, VnodeKind};
 use error::Errno;
 use libcommon::{path_component_left, path_component_right};
 
@@ -17,7 +17,7 @@ impl Ioctx {
         }
     }
 
-    fn _find(&self, mut at: VnodeRef, path: &str) -> Result<VnodeRef, Errno> {
+    fn _find(&self, mut at: VnodeRef, path: &str, follow: bool) -> Result<VnodeRef, Errno> {
         let mut element;
         let mut rest = path;
 
@@ -42,17 +42,27 @@ impl Ioctx {
         }
         assert!(!element.is_empty());
 
-        let node = at.lookup_or_load(element)?;
+        let mut node = at.lookup_or_load(element)?;
+
+        while let Some(target) = node.target() {
+            assert!(node.kind() == VnodeKind::Directory);
+            node = target;
+        }
 
         if rest.is_empty() {
             Ok(node)
         } else {
-            self._find(node, rest)
+            self._find(node, rest, follow)
         }
     }
 
     /// Looks up a path in given ioctx
-    pub fn find(&self, at: Option<VnodeRef>, mut path: &str) -> Result<VnodeRef, Errno> {
+    pub fn find(
+        &self,
+        at: Option<VnodeRef>,
+        mut path: &str,
+        follow: bool,
+    ) -> Result<VnodeRef, Errno> {
         let at = if path.starts_with('/') {
             path = path.trim_start_matches('/');
             self.root.clone()
@@ -62,7 +72,7 @@ impl Ioctx {
             self.cwd.clone()
         };
 
-        self._find(at, path)
+        self._find(at, path, follow)
     }
 
     /// Creates a new directory
@@ -73,7 +83,7 @@ impl Ioctx {
         mode: FileMode,
     ) -> Result<VnodeRef, Errno> {
         let (parent, name) = path_component_right(path);
-        self.find(at, parent)?.mkdir(name, mode)
+        self.find(at, parent, true)?.mkdir(name.trim_start_matches('/'), mode)
     }
 }
 
@@ -147,42 +157,65 @@ mod tests {
 
         let ioctx = Ioctx::new(root.clone());
 
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/").unwrap()));
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/.").unwrap()));
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/./.").unwrap()));
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/.///.").unwrap()));
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/..").unwrap()));
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/../").unwrap()));
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/../.").unwrap()));
-        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/../..").unwrap()));
+        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/", false).unwrap()));
+        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/.", false).unwrap()));
+        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/./.", false).unwrap()));
+        assert!(Rc::ptr_eq(
+            &root,
+            &ioctx.find(None, "/.///.", false).unwrap()
+        ));
+        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/..", false).unwrap()));
+        assert!(Rc::ptr_eq(&root, &ioctx.find(None, "/../", false).unwrap()));
+        assert!(Rc::ptr_eq(
+            &root,
+            &ioctx.find(None, "/../.", false).unwrap()
+        ));
+        assert!(Rc::ptr_eq(
+            &root,
+            &ioctx.find(None, "/../..", false).unwrap()
+        ));
 
-        assert!(Rc::ptr_eq(&d0, &ioctx.find(None, "/dir0").unwrap()));
-        assert!(Rc::ptr_eq(&d1, &ioctx.find(None, "/dir1").unwrap()));
-        assert!(Rc::ptr_eq(&d0, &ioctx.find(None, "/dir1/../dir0").unwrap()));
+        assert!(Rc::ptr_eq(&d0, &ioctx.find(None, "/dir0", false).unwrap()));
+        assert!(Rc::ptr_eq(&d1, &ioctx.find(None, "/dir1", false).unwrap()));
+        assert!(Rc::ptr_eq(
+            &d0,
+            &ioctx.find(None, "/dir1/../dir0", false).unwrap()
+        ));
         assert!(Rc::ptr_eq(
             &d1,
-            &ioctx.find(None, "/dir1/../dir0/./../../.././dir1").unwrap()
+            &ioctx
+                .find(None, "/dir1/../dir0/./../../.././dir1", false)
+                .unwrap()
         ));
 
-        assert!(Rc::ptr_eq(&d0d0, &ioctx.find(None, "/dir0/dir0").unwrap()));
         assert!(Rc::ptr_eq(
             &d0d0,
-            &ioctx.find(None, "/dir0/dir0/.").unwrap()
+            &ioctx.find(None, "/dir0/dir0", false).unwrap()
         ));
-        assert!(Rc::ptr_eq(&d0, &ioctx.find(None, "/dir0/dir0/..").unwrap()));
         assert!(Rc::ptr_eq(
-            &d0,
-            &ioctx.find(None, "/dir0/dir0/../").unwrap()
+            &d0d0,
+            &ioctx.find(None, "/dir0/dir0/.", false).unwrap()
         ));
         assert!(Rc::ptr_eq(
             &d0,
-            &ioctx.find(None, "/dir0/dir0/../.").unwrap()
+            &ioctx.find(None, "/dir0/dir0/..", false).unwrap()
+        ));
+        assert!(Rc::ptr_eq(
+            &d0,
+            &ioctx.find(None, "/dir0/dir0/../", false).unwrap()
+        ));
+        assert!(Rc::ptr_eq(
+            &d0,
+            &ioctx.find(None, "/dir0/dir0/../.", false).unwrap()
         ));
 
-        assert!(Rc::ptr_eq(&d0f0, &ioctx.find(None, "/dir0/file0").unwrap()));
         assert!(Rc::ptr_eq(
             &d0f0,
-            &ioctx.find(None, "/dir1/../dir0/./file0").unwrap()
+            &ioctx.find(None, "/dir0/file0", false).unwrap()
+        ));
+        assert!(Rc::ptr_eq(
+            &d0f0,
+            &ioctx.find(None, "/dir1/../dir0/./file0", false).unwrap()
         ));
     }
 
@@ -198,11 +231,11 @@ mod tests {
         let ioctx = Ioctx::new(root.clone());
 
         assert_eq!(
-            ioctx.find(None, "/dir0/file0/.").unwrap_err(),
+            ioctx.find(None, "/dir0/file0/.", false).unwrap_err(),
             Errno::NotADirectory
         );
         assert_eq!(
-            ioctx.find(None, "/dir0/file0/..").unwrap_err(),
+            ioctx.find(None, "/dir0/file0/..", false).unwrap_err(),
             Errno::NotADirectory
         );
 
@@ -225,4 +258,27 @@ mod tests {
             Errno::AlreadyExists
         );
     }
+
+    #[test]
+    fn test_find_mount() {
+        let root_outer = Vnode::new("", VnodeKind::Directory, 0);
+        let dir0 = Vnode::new("dir0", VnodeKind::Directory, 0);
+        let root_inner = Vnode::new("", VnodeKind::Directory, 0);
+        let dir1 = Vnode::new("dir1", VnodeKind::Directory, 0);
+
+        root_outer.clone().attach(dir0.clone());
+        root_inner.clone().attach(dir1.clone());
+
+        let ioctx = Ioctx::new(root_outer.clone());
+
+        assert_eq!(ioctx.find(None, "/dir0/dir1", false).unwrap_err(), Errno::DoesNotExist);
+
+        dir0.mount(root_inner.clone()).unwrap();
+
+        assert!(Rc::ptr_eq(&root_inner, &ioctx.find(None, "/dir0", false).unwrap()));
+        assert!(Rc::ptr_eq(&dir1, &ioctx.find(None, "/dir0/dir1", false).unwrap()));
+        assert!(Rc::ptr_eq(&root_inner, &ioctx.find(None, "/dir0/dir1/..", false).unwrap()));
+        assert!(Rc::ptr_eq(&dir0, &ioctx.find(None, "/dir0/dir1/../..", false).unwrap()));
+        assert!(Rc::ptr_eq(&root_outer, &ioctx.find(None, "/dir0/dir1/../../..", false).unwrap()));
+    }
 }
diff --git a/fs/vfs/src/lib.rs b/fs/vfs/src/lib.rs
index 0881fdd..1afae46 100644
--- a/fs/vfs/src/lib.rs
+++ b/fs/vfs/src/lib.rs
@@ -1,8 +1,12 @@
 //! Virtual filesystem API and facilities
 #![warn(missing_docs)]
-#![feature(destructuring_assignment)]
+#![feature(destructuring_assignment, const_fn_trait_bound)]
 #![no_std]
 
+#[cfg(test)]
+#[macro_use]
+extern crate std;
+
 extern crate alloc;
 
 mod block;
@@ -17,3 +21,5 @@ mod ioctx;
 pub use ioctx::Ioctx;
 mod file;
 pub use file::File;
+mod char;
+pub use crate::char::{CharDevice, CharDeviceWrapper};
diff --git a/fs/vfs/src/node.rs b/fs/vfs/src/node.rs
index b2ac043..695c726 100644
--- a/fs/vfs/src/node.rs
+++ b/fs/vfs/src/node.rs
@@ -14,6 +14,10 @@ pub enum VnodeKind {
     Directory,
     /// Node is a regular file
     Regular,
+    /// Node is a character device
+    Char,
+    /// Node is a block device
+    Block,
 }
 
 pub(crate) struct TreeNode {
@@ -36,6 +40,7 @@ pub struct Vnode {
     kind: VnodeKind,
     flags: u32,
 
+    target: RefCell<Option<VnodeRef>>,
     fs: RefCell<Option<Rc<dyn Filesystem>>>,
     data: RefCell<Option<Box<dyn VnodeImpl>>>,
 }
@@ -88,11 +93,17 @@ impl Vnode {
                 parent: None,
                 children: Vec::new(),
             }),
+            target: RefCell::new(None),
             fs: RefCell::new(None),
             data: RefCell::new(None),
         })
     }
 
+    ///
+    pub fn name<'a>(&'a self) -> &'a str {
+        &self.name
+    }
+
     /// Sets an associated [VnodeImpl] for the [Vnode]
     pub fn set_data(&self, data: Box<dyn VnodeImpl>) {
         *self.data.borrow_mut() = Some(data);
@@ -158,11 +169,38 @@ impl Vnode {
         parent_borrow.children.remove(index);
     }
 
+    ///
+    pub fn mount(self: &VnodeRef, root: VnodeRef) -> Result<(), Errno> {
+        if !self.is_directory() {
+            return Err(Errno::NotADirectory);
+        }
+        if !root.is_directory() {
+            return Err(Errno::NotADirectory);
+        }
+        if self.target.borrow().is_some() {
+            return Err(Errno::InvalidArgument);
+        }
+
+        let mut child_borrow = root.tree.borrow_mut();
+        if child_borrow.parent.is_some() {
+            return Err(Errno::InvalidArgument);
+        }
+        child_borrow.parent = Some(self.clone());
+        *self.target.borrow_mut() = Some(root.clone());
+
+        Ok(())
+    }
+
     /// Returns this vnode's parent or itself if it has none
     pub fn parent(self: &VnodeRef) -> VnodeRef {
         self.tree.borrow().parent.as_ref().unwrap_or(self).clone()
     }
 
+    ///
+    pub fn target(self: &VnodeRef) -> Option<VnodeRef> {
+        self.target.borrow().clone()
+    }
+
     /// Looks up a child `name` in in-memory tree cache
     pub fn lookup(self: &VnodeRef, name: &str) -> Option<VnodeRef> {
         assert!(self.is_directory());
@@ -189,7 +227,7 @@ impl Vnode {
             self.attach(vnode.clone());
             Ok(vnode)
         } else {
-            Err(Errno::NotImplemented)
+            Err(Errno::DoesNotExist)
         }
     }
 
@@ -198,6 +236,9 @@ impl Vnode {
         if self.kind != VnodeKind::Directory {
             return Err(Errno::NotADirectory);
         }
+        if name.contains('/') {
+            return Err(Errno::InvalidArgument);
+        }
 
         match self.lookup_or_load(name) {
             Err(Errno::DoesNotExist) => {}
@@ -223,6 +264,9 @@ impl Vnode {
         if self.kind != VnodeKind::Directory {
             return Err(Errno::NotADirectory);
         }
+        if name.contains('/') {
+            return Err(Errno::InvalidArgument);
+        }
 
         if let Some(ref mut data) = *self.data() {
             let vnode = self.lookup(name).ok_or(Errno::DoesNotExist)?;
@@ -236,7 +280,7 @@ impl Vnode {
 
     /// Opens a vnode for access
     pub fn open(self: &VnodeRef) -> Result<File, Errno> {
-        if self.kind != VnodeKind::Regular {
+        if self.kind == VnodeKind::Directory {
             return Err(Errno::IsADirectory);
         }
 
@@ -250,7 +294,7 @@ impl Vnode {
 
     /// Reads data from offset `pos` into `buf`
     pub fn read(self: &VnodeRef, pos: usize, buf: &mut [u8]) -> Result<usize, Errno> {
-        if self.kind != VnodeKind::Regular {
+        if self.kind == VnodeKind::Directory {
             return Err(Errno::IsADirectory);
         }
 
@@ -263,7 +307,7 @@ impl Vnode {
 
     /// Writes data from `buf` to offset `pos`
     pub fn write(self: &VnodeRef, pos: usize, buf: &[u8]) -> Result<usize, Errno> {
-        if self.kind != VnodeKind::Regular {
+        if self.kind == VnodeKind::Directory {
             return Err(Errno::IsADirectory);
         }
 
diff --git a/init/src/main.rs b/init/src/main.rs
index 4226c75..3b2e91f 100644
--- a/init/src/main.rs
+++ b/init/src/main.rs
@@ -8,10 +8,10 @@ extern crate libusr;
 #[no_mangle]
 fn main() -> i32 {
     loop {
+        println!("Hello to stdout");
         trace!("Hello from userspace");
         unsafe {
             asm!("svc #0", in("x8") 121, in("x0") 1000000000);
         }
     }
-    123
 }
diff --git a/kernel/src/arch/aarch64/boot/mod.rs b/kernel/src/arch/aarch64/boot/mod.rs
index a595818..58698e4 100644
--- a/kernel/src/arch/aarch64/boot/mod.rs
+++ b/kernel/src/arch/aarch64/boot/mod.rs
@@ -4,6 +4,7 @@ use crate::arch::{
     aarch64::reg::{CNTKCTL_EL1, CPACR_EL1},
     machine,
 };
+use crate::fs::devfs;
 use crate::dev::{fdt::DeviceTree, irq::IntSource, Device};
 //use crate::debug::Level;
 use crate::mem::{
@@ -56,6 +57,8 @@ extern "C" fn __aa64_bsp_main(fdt_base: usize) -> ! {
         heap::init(heap_base_virt, 16 * 1024 * 1024);
     }
 
+    devfs::init();
+
     machine::init_board().unwrap();
 
     let initrd;
diff --git a/kernel/src/arch/aarch64/context.S b/kernel/src/arch/aarch64/context.S
index e7da456..1a3f16e 100644
--- a/kernel/src/arch/aarch64/context.S
+++ b/kernel/src/arch/aarch64/context.S
@@ -3,12 +3,11 @@
 .global __aa64_ctx_switch_to
 .global __aa64_ctx_enter_kernel
 
-.set PT_REGS_SIZE, 16 * 6
+.set PT_REGS_SIZE, 16 * 7
 
 __aa64_ctx_enter_user:
     ldp x0, x1, [sp, #0]
     msr sp_el0, x0
-    msr ttbr0_el1, x1
 
     msr spsr_el1, xzr
     ldp x0, x1, [sp, #16]
@@ -21,7 +20,6 @@ __return_to_user:
 
 __aa64_ctx_enter_kernel:
     msr sp_el0, xzr
-    msr ttbr0_el1, xzr
 
     mov x0, #5
     msr spsr_el1, x0
@@ -41,6 +39,8 @@ __aa64_ctx_switch:
     stp x25, x26, [sp, #16 * 3]
     stp x27, x28, [sp, #16 * 4]
     stp x29, x30, [sp, #16 * 5]
+    mrs x19, TTBR0_EL1
+    stp x19, xzr, [sp, #16 * 6]
 
     mov x19, sp
     str x19, [x1]
@@ -48,6 +48,8 @@ __aa64_ctx_switch_to:
     ldr x0, [x0]
     mov sp, x0
 
+    ldp x19, xzr, [sp, #16 * 6]
+    msr TTBR0_EL1, x19
     ldp x19, x20, [sp, #16 * 0]
     ldp x21, x22, [sp, #16 * 1]
     ldp x23, x24, [sp, #16 * 2]
diff --git a/kernel/src/arch/aarch64/context.rs b/kernel/src/arch/aarch64/context.rs
index c62c559..d396314 100644
--- a/kernel/src/arch/aarch64/context.rs
+++ b/kernel/src/arch/aarch64/context.rs
@@ -29,7 +29,7 @@ impl Context {
         stack.push(entry);
         stack.push(arg);
 
-        stack.setup_common(__aa64_ctx_enter_kernel as usize);
+        stack.setup_common(__aa64_ctx_enter_kernel as usize, 0);
 
         Self {
             k_sp: stack.sp,
@@ -45,10 +45,10 @@ impl Context {
 
         stack.push(entry);
         stack.push(arg);
-        stack.push(ttbr0);
+        stack.push(/* ttbr0 */ 0);
         stack.push(ustack);
 
-        stack.setup_common(__aa64_ctx_enter_user as usize);
+        stack.setup_common(__aa64_ctx_enter_user as usize, ttbr0);
 
         Self {
             k_sp: stack.sp,
@@ -89,7 +89,9 @@ impl Stack {
         }
     }
 
-    pub fn setup_common(&mut self, entry: usize) {
+    pub fn setup_common(&mut self, entry: usize, ttbr: usize) {
+        self.push(0);
+        self.push(ttbr);
         self.push(entry); // x30/lr
         self.push(0); // x29
         self.push(0); // x28
diff --git a/kernel/src/arch/aarch64/exception.rs b/kernel/src/arch/aarch64/exception.rs
index 29d16d8..e52cd90 100644
--- a/kernel/src/arch/aarch64/exception.rs
+++ b/kernel/src/arch/aarch64/exception.rs
@@ -85,7 +85,10 @@ extern "C" fn __aa64_exc_sync_handler(exc: &mut ExceptionFrame) {
             unsafe {
                 match syscall::syscall(exc.x[8], &exc.x[..6]) {
                     Ok(val) => exc.x[0] = val,
-                    Err(_) => exc.x[0] = usize::MAX,
+                    Err(err) => {
+                        warnln!("syscall {} failed: {:?}", exc.x[8], err);
+                        exc.x[0] = usize::MAX
+                    },
                 }
             }
             return;
diff --git a/kernel/src/arch/aarch64/mach_qemu/mod.rs b/kernel/src/arch/aarch64/mach_qemu/mod.rs
index 39de913..be8039f 100644
--- a/kernel/src/arch/aarch64/mach_qemu/mod.rs
+++ b/kernel/src/arch/aarch64/mach_qemu/mod.rs
@@ -11,6 +11,7 @@ use crate::dev::{
     serial::{pl011::Pl011, SerialDevice},
     Device,
 };
+use crate::fs::devfs;
 use crate::mem::phys;
 use error::Errno;
 
@@ -46,6 +47,7 @@ pub fn init_board() -> Result<(), Errno> {
         GIC.enable()?;
 
         UART0.init_irqs()?;
+        devfs::add_char_device("uart0", &UART0)?;
 
         RTC.enable()?;
         RTC.init_irqs()?;
diff --git a/kernel/src/arch/aarch64/vectors.S b/kernel/src/arch/aarch64/vectors.S
index 29d2ff9..922adc8 100644
--- a/kernel/src/arch/aarch64/vectors.S
+++ b/kernel/src/arch/aarch64/vectors.S
@@ -26,7 +26,7 @@
     mrs x0, spsr_el1
     mrs x1, elr_el1
     mrs x2, sp_el0
-    mrs x3, ttbr0_el1
+//  mrs x3, ttbr0_el1
 
     stp x0,  x1,  [sp, #16 * 16]
     stp x2,  x3,  [sp, #16 * 17]
@@ -38,7 +38,7 @@
     msr spsr_el1, x0
     msr elr_el1, x1
     msr sp_el0, x2
-    msr ttbr0_el1, x3
+//  msr ttbr0_el1, x3
 
     ldp x0,  x1,  [sp, #16 * 0]
     ldp x2,  x3,  [sp, #16 * 1]
diff --git a/kernel/src/dev/mod.rs b/kernel/src/dev/mod.rs
index 79f2102..fda658b 100644
--- a/kernel/src/dev/mod.rs
+++ b/kernel/src/dev/mod.rs
@@ -13,6 +13,8 @@ pub mod pci;
 pub mod rtc;
 pub mod serial;
 pub mod timer;
+#[allow(missing_docs)]
+pub mod tty;
 
 /// Generic device trait
 pub trait Device {
diff --git a/kernel/src/dev/serial/pl011.rs b/kernel/src/dev/serial/pl011.rs
index 5d13d6e..4f529ae 100644
--- a/kernel/src/dev/serial/pl011.rs
+++ b/kernel/src/dev/serial/pl011.rs
@@ -4,7 +4,7 @@ use crate::arch::machine::{self, IrqNumber};
 use crate::dev::{
     irq::{IntController, IntSource},
     serial::SerialDevice,
-    Device,
+    tty::CharRing, Device,
 };
 use crate::mem::virt::DeviceMemoryIo;
 use crate::sync::IrqSafeSpinLock;
@@ -16,6 +16,7 @@ use tock_registers::{
     register_bitfields, register_structs,
     registers::{ReadOnly, ReadWrite, WriteOnly},
 };
+use vfs::CharDevice;
 
 register_bitfields! {
     u32,
@@ -78,6 +79,7 @@ struct Pl011Inner {
 /// Device struct for PL011
 pub struct Pl011 {
     inner: InitOnce<IrqSafeSpinLock<Pl011Inner>>,
+    ring: CharRing<16>,
     base: usize,
     irq: IrqNumber,
 }
@@ -135,7 +137,8 @@ impl IntSource for Pl011 {
 
         let byte = inner.regs.DR.get();
         drop(inner);
-        debugln!("irq byte = {:#04x}", byte);
+
+        self.ring.putc(byte as u8, false).ok();
 
         Ok(())
     }
@@ -166,6 +169,23 @@ impl SerialDevice for Pl011 {
     }
 }
 
+impl CharDevice for Pl011 {
+    fn read(&self, blocking: bool, data: &mut [u8]) -> Result<usize, Errno> {
+        assert!(blocking);
+        self.ring.line_read(data, self)
+    }
+
+    fn write(&self, blocking: bool, data: &[u8]) -> Result<usize, Errno> {
+        assert!(blocking);
+        for &byte in data {
+            unsafe {
+                self.inner.get().lock().send(byte);
+            }
+        }
+        Ok(data.len())
+    }
+}
+
 impl Device for Pl011 {
     fn name(&self) -> &'static str {
         "PL011 UART"
@@ -192,6 +212,7 @@ impl Pl011 {
     pub const unsafe fn new(base: usize, irq: IrqNumber) -> Self {
         Self {
             inner: InitOnce::new(),
+            ring: CharRing::new(),
             base,
             irq,
         }
diff --git a/kernel/src/dev/timer.rs b/kernel/src/dev/timer.rs
index a946442..4494fda 100644
--- a/kernel/src/dev/timer.rs
+++ b/kernel/src/dev/timer.rs
@@ -1,7 +1,6 @@
 //! Timer interface
 
 use crate::dev::Device;
-use crate::proc::Pid;
 use core::time::Duration;
 use error::Errno;
 
@@ -10,9 +9,3 @@ pub trait TimestampSource: Device {
     /// Reads current timestamp as a [Duration] from system start time
     fn timestamp(&self) -> Result<Duration, Errno>;
 }
-
-///
-pub struct Sleep {
-    deadline: Duration,
-    pid: Pid
-}
diff --git a/kernel/src/dev/tty.rs b/kernel/src/dev/tty.rs
new file mode 100644
index 0000000..db0ddcb
--- /dev/null
+++ b/kernel/src/dev/tty.rs
@@ -0,0 +1,133 @@
+use error::Errno;
+use crate::proc::wait::Wait;
+use crate::sync::IrqSafeSpinLock;
+use vfs::CharDevice;
+
+#[allow(missing_docs)]
+#[derive(Debug)]
+struct CharRingInner<const N: usize> {
+    rd: usize,
+    wr: usize,
+    data: [u8; N],
+    flags: u8
+}
+
+///
+pub struct CharRing<const N: usize> {
+    wait_read: Wait,
+    wait_write: Wait,
+    inner: IrqSafeSpinLock<CharRingInner<N>>,
+}
+
+#[allow(missing_docs)]
+impl<const N: usize> CharRingInner<N> {
+    #[inline]
+    const fn is_readable(&self) -> bool {
+        if self.rd <= self.wr {
+            (self.wr - self.rd) > 0
+        } else {
+            (self.wr + (N - self.rd)) > 0
+        }
+    }
+
+    #[inline]
+    fn read_unchecked(&mut self) -> u8 {
+        let res = self.data[self.rd];
+        self.rd = (self.rd + 1) % N;
+        res
+    }
+
+    #[inline]
+    fn write_unchecked(&mut self, ch: u8) {
+        self.data[self.wr] = ch;
+        self.wr = (self.wr + 1) % N;
+    }
+}
+
+#[allow(missing_docs)]
+impl<const N: usize> CharRing<N> {
+    pub const fn new() -> Self {
+        Self {
+            inner: IrqSafeSpinLock::new(CharRingInner {
+                rd: 0,
+                wr: 0,
+                data: [0; N],
+                flags: 0
+            }),
+            wait_read: Wait::new(),
+            wait_write: Wait::new(),
+        }
+    }
+
+    pub fn getc(&self) -> Result<u8, Errno> {
+        let mut lock = self.inner.lock();
+        loop {
+            if !lock.is_readable() && lock.flags == 0 {
+                drop(lock);
+                self.wait_read.sleep_on(None)?;
+                lock = self.inner.lock();
+            } else {
+                break;
+            }
+        }
+        if lock.flags != 0 {
+            todo!();
+        }
+        let byte = lock.read_unchecked();
+        self.wait_write.wakeup_one();
+        Ok(byte)
+    }
+
+    pub fn dump(&self) {
+        debugln!("{:?}", self.inner.lock());
+    }
+
+    pub fn putc(&self, ch: u8, blocking: bool) -> Result<(), Errno> {
+        let mut lock = self.inner.lock();
+        if blocking {
+            todo!()
+        }
+        lock.write_unchecked(ch);
+        self.wait_read.wakeup_one();
+        Ok(())
+    }
+
+    pub fn line_read<T: CharDevice>(&self, data: &mut [u8], dev: &T) -> Result<usize, Errno> {
+        let mut rem = data.len();
+        let mut off = 0;
+
+        while rem != 0 {
+            let byte = match self.getc() {
+                Ok(ch) => ch,
+                Err(Errno::Interrupt) => {
+                    todo!()
+                },
+                Err(Errno::EndOfFile) => {
+                    todo!()
+                },
+                Err(e) => return Err(e),
+            };
+
+            if byte == b'\n' || byte == b'\r' {
+                break;
+            }
+
+            if byte == 0x7F {
+                if off > 0 {
+                    dev.write(true, b"\x1B[D \x1B[D").ok();
+                    off -= 1;
+                    rem += 1;
+                }
+                continue;
+            } else if byte >= b' ' {
+                // TODO tty options
+                dev.write(true, &[byte]).ok();
+            }
+
+            data[off] = byte;
+            off += 1;
+            rem -= 1;
+        }
+        Ok(off)
+    }
+}
diff --git a/kernel/src/fs/devfs.rs b/kernel/src/fs/devfs.rs
new file mode 100644
index 0000000..a938891
--- /dev/null
+++ b/kernel/src/fs/devfs.rs
@@ -0,0 +1,24 @@
+use vfs::{Vnode, VnodeKind, CharDevice, VnodeRef, CharDeviceWrapper};
+use alloc::boxed::Box;
+use crate::util::InitOnce;
+use error::Errno;
+
+static DEVFS_ROOT: InitOnce<VnodeRef> = InitOnce::new();
+
+pub fn init() {
+    DEVFS_ROOT.init(Vnode::new("", VnodeKind::Directory, 0));
+}
+
+pub fn root() -> &'static VnodeRef {
+    DEVFS_ROOT.get()
+}
+
+pub fn add_char_device(name: &str, dev: &'static dyn CharDevice) -> Result<(), Errno> {
+    debugln!("Add device: {}", name);
+    let node = Vnode::new(name, VnodeKind::Char, 0);
+    node.set_data(Box::new(CharDeviceWrapper::new(dev)));
+
+    DEVFS_ROOT.get().attach(node);
+
+    Ok(())
+}
diff --git a/kernel/src/fs/mod.rs b/kernel/src/fs/mod.rs
index d336cf1..193bf02 100644
--- a/kernel/src/fs/mod.rs
+++ b/kernel/src/fs/mod.rs
@@ -6,6 +6,8 @@ use crate::mem::{
 };
 use memfs::BlockAllocator;
 
+pub mod devfs;
+
 #[derive(Clone, Copy)]
 pub struct MemfsBlockAlloc;
 
diff --git a/kernel/src/proc/mod.rs b/kernel/src/proc/mod.rs
index c998390..0fe6641 100644
--- a/kernel/src/proc/mod.rs
+++ b/kernel/src/proc/mod.rs
@@ -63,12 +63,13 @@ pub unsafe fn enter(initrd: Option<(usize, usize)>) -> ! {
 
     spawn!(fn (initrd_ptr: usize) {
         use memfs::Ramfs;
-        use vfs::{Filesystem, Ioctx};
-        use crate::fs::MemfsBlockAlloc;
+        use vfs::{Filesystem, Ioctx, FileMode};
+        use crate::fs::{MemfsBlockAlloc, devfs};
         debugln!("Running kernel init process");
 
         let initrd = unsafe { *(initrd_ptr as *const Option<(usize, usize)>) };
         if let Some((start, end)) = initrd {
+            let proc = Process::current();
             let size = end - start;
             let start = mem::virtualize(start);
 
@@ -78,12 +79,27 @@ pub unsafe fn enter(initrd: Option<(usize, usize)>) -> ! {
             };
             infoln!("Done constructing ramfs");
             let root = fs.root().unwrap();
+            let devfs_root = devfs::root();
+
+            let dir = root.mkdir("dev", FileMode::default_dir()).unwrap();
+            dir.mount(devfs_root.clone()).unwrap();
+
             let ioctx = Ioctx::new(root);
 
             // Open a test file
-            let node = ioctx.find(None, "/init").unwrap();
+            let node = ioctx.find(None, "/init", true).unwrap();
             let mut file = node.open().unwrap();
 
+            proc.set_ioctx(ioctx);
+
+            // Open stdout
+            {
+                let mut io = proc.io.lock();
+                let node = io.ioctx.as_ref().unwrap().find(None, "/dev/uart0", true).unwrap();
+                // TODO fd cloning?
+                io.files.push(node.open().unwrap());
+            }
+
             Process::execve(|space| elf::load_elf(space, &mut file), 0).unwrap();
         } else {
             infoln!("No initrd, exiting!");
diff --git a/kernel/src/proc/process.rs b/kernel/src/proc/process.rs
index 32fce41..c2230a2 100644
--- a/kernel/src/proc/process.rs
+++ b/kernel/src/proc/process.rs
@@ -6,11 +6,13 @@ use crate::mem::{
 };
 use crate::proc::{PROCESSES, SCHED};
 use crate::sync::IrqSafeSpinLock;
-use alloc::rc::Rc;
+use alloc::{vec::Vec, rc::Rc};
 use core::cell::UnsafeCell;
 use core::fmt;
 use core::sync::atomic::{AtomicU32, Ordering};
 use error::Errno;
+use vfs::Ioctx;
+use vfs::File;
 
 pub use crate::arch::platform::context::{self, Context};
 
@@ -48,11 +50,21 @@ struct ProcessInner {
     exit: Option<ExitCode>,
 }
 
+///
+pub struct ProcessIo {
+    ///
+    pub ioctx: Option<Ioctx>,
+    ///
+    pub files: Vec<File>,
+}
+
 /// Structure describing an operating system process
 #[allow(dead_code)]
 pub struct Process {
     ctx: UnsafeCell<Context>,
     inner: IrqSafeSpinLock<ProcessInner>,
+    ///
+    pub io: IrqSafeSpinLock<ProcessIo>,
 }
 
 impl From<i32> for ExitCode {
@@ -126,6 +138,11 @@ impl Process {
     const USTACK_VIRT_TOP: usize = 0x100000000;
     const USTACK_PAGES: usize = 4;
 
+    ///
+    pub fn set_ioctx(&self, ioctx: Ioctx) {
+        self.io.lock().ioctx = Some(ioctx);
+    }
+
     /// Returns currently executing process
     pub fn current() -> ProcessRef {
         SCHED.current_process()
@@ -206,6 +223,10 @@ impl Process {
         let id = Pid::new_kernel();
         let res = Rc::new(Self {
             ctx: UnsafeCell::new(Context::kernel(entry as usize, arg)),
+            io: IrqSafeSpinLock::new(ProcessIo {
+                ioctx: None,
+                files: Vec::new(),
+            }),
             inner: IrqSafeSpinLock::new(ProcessInner {
                 id,
                 exit: None,
diff --git a/kernel/src/proc/wait.rs b/kernel/src/proc/wait.rs
index c7cccaf..416f733 100644
--- a/kernel/src/proc/wait.rs
+++ b/kernel/src/proc/wait.rs
@@ -1,8 +1,8 @@
 use crate::arch::machine;
-use crate::proc::{self, sched::SCHED, Pid, Process, ProcessState};
 use crate::dev::timer::TimestampSource;
+use crate::proc::{self, sched::SCHED, Pid, Process};
 use crate::sync::IrqSafeSpinLock;
-use alloc::{vec::Vec, collections::{VecDeque, LinkedList}};
+use alloc::collections::LinkedList;
 use core::time::Duration;
 use error::Errno;
 
@@ -12,7 +12,7 @@ pub struct Wait {
 
 pub struct Timeout {
     pid: Pid,
-    deadline: Duration
+    deadline: Duration,
 }
 
 static TICK_LIST: IrqSafeSpinLock<LinkedList<Timeout>> = IrqSafeSpinLock::new(LinkedList::new());
@@ -36,13 +36,13 @@ pub fn tick() {
 pub fn sleep(timeout: Duration) {
     // Dummy wait descriptor which will never receive notifications
     static SLEEP_NOTIFY: Wait = Wait::new();
-    SLEEP_NOTIFY.sleep_on(Some(timeout));
+    SLEEP_NOTIFY.sleep_on(Some(timeout)).ok();
 }
 
 impl Wait {
     pub const fn new() -> Self {
         Self {
-            queue: IrqSafeSpinLock::new(LinkedList::new())
+            queue: IrqSafeSpinLock::new(LinkedList::new()),
         }
     }
 
@@ -74,14 +74,14 @@ impl Wait {
     pub fn sleep_on(&self, timeout: Option<Duration>) -> Result<(), Errno> {
         let proc = Process::current();
         let deadline = timeout.map(|t| machine::local_timer().timestamp().unwrap() + t);
-        let mut queue_lock = Some(self.queue.lock());
+        let mut queue_lock = self.queue.lock();
 
-        queue_lock.as_mut().unwrap().push_back(proc.id());
+        queue_lock.push_back(proc.id());
         proc.set_wait_flag(true);
         if let Some(deadline) = deadline {
             TICK_LIST.lock().push_back(Timeout {
                 pid: proc.id(),
-                deadline
+                deadline,
             });
         }
 
@@ -90,13 +90,13 @@ impl Wait {
                 return Ok(());
             }
 
-            queue_lock = None;
+            drop(queue_lock);
             proc.enter_wait();
-            queue_lock = Some(self.queue.lock());
+            queue_lock = self.queue.lock();
 
             if let Some(deadline) = deadline {
                 if machine::local_timer().timestamp()? > deadline {
-                    let mut cursor = queue_lock.as_mut().unwrap().cursor_front_mut();
+                    let mut cursor = queue_lock.cursor_front_mut();
 
                     while let Some(&mut item) = cursor.current() {
                         if proc.id() == item {
diff --git a/kernel/src/sync.rs b/kernel/src/sync.rs
index 49ae64d..6102a37 100644
--- a/kernel/src/sync.rs
+++ b/kernel/src/sync.rs
@@ -4,6 +4,7 @@ use crate::arch::platform::{irq_mask_save, irq_restore};
 use core::cell::UnsafeCell;
 use core::ops::{Deref, DerefMut};
 use core::sync::atomic::{AtomicBool, Ordering};
+use core::fmt;
 
 /// Lock structure ensuring IRQs are disabled when inner value is accessed
 pub struct IrqSafeSpinLock<T> {
@@ -70,6 +71,12 @@ impl<T> DerefMut for IrqSafeSpinLockGuard<'_, T> {
     }
 }
 
+impl<T> fmt::Debug for IrqSafeSpinLockGuard<'_, T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{:?}", &*self)
+    }
+}
+
 impl<T> Drop for IrqSafeSpinLockGuard<'_, T> {
     #[inline(always)]
     fn drop(&mut self) {
diff --git a/kernel/src/syscall.rs b/kernel/src/syscall.rs
index 450d6d6..1a57a33 100644
--- a/kernel/src/syscall.rs
+++ b/kernel/src/syscall.rs
@@ -13,7 +13,7 @@ fn translate(virt: usize) -> Option<usize> {
     }
 }
 
-fn validate_user_ptr(base: usize, len: usize) -> Result<(), Errno> {
+fn validate_user_ptr<'a>(base: usize, len: usize) -> Result<&'a mut [u8], Errno> {
     if base > mem::KERNEL_OFFSET || base + len > mem::KERNEL_OFFSET {
         warnln!(
             "User region refers to kernel memory: base={:#x}, len={:#x}",
@@ -35,7 +35,48 @@ fn validate_user_ptr(base: usize, len: usize) -> Result<(), Errno> {
         }
     }
 
-    Ok(())
+    Ok(unsafe { core::slice::from_raw_parts_mut(base as *mut u8, len) })
+}
+
+fn validate_user_str<'a>(base: usize, limit: usize) -> Result<&'a str, Errno> {
+    if base > mem::KERNEL_OFFSET {
+        warnln!("User string refers to kernel memory: base={:#x}", base);
+        return Err(Errno::InvalidArgument);
+    }
+
+    let base_ptr = base as *const u8;
+    let mut len = 0;
+    let mut page_valid = false;
+    loop {
+        if len == limit {
+            warnln!("User string exceeded limit: base={:#x}", base);
+            return Err(Errno::InvalidArgument);
+        }
+
+        if (base + len) % mem::PAGE_SIZE == 0 {
+            page_valid = false;
+        }
+
+        if !page_valid && translate((base + len) & !0xFFF).is_none() {
+            warnln!("User string refers to unmapped memory: base={:#x}, off={:#x}", base, len);
+            return Err(Errno::InvalidArgument);
+        }
+
+        page_valid = true;
+
+        let byte = unsafe { *base_ptr.add(len) };
+        if byte == 0 {
+            break;
+        }
+
+        len += 1;
+    }
+
+    let slice = unsafe { core::slice::from_raw_parts(base_ptr, len) };
+    core::str::from_utf8(slice).map_err(|_| {
+        warnln!("User string contains invalid UTF-8 characters: base={:#x}", base);
+        Errno::InvalidArgument
+    })
 }
 
 pub unsafe fn syscall(num: usize, args: &[usize]) -> Result<usize, Errno> {
@@ -68,6 +109,40 @@ pub unsafe fn syscall(num: usize, args: &[usize]) -> Result<usize, Errno> {
 
             Ok(0)
         }
+        // sys_open
+        2 => {
+            use crate::proc::Process;
+            let path = validate_user_str(args[0], 256)?;
+
+            let proc = Process::current();
+            let mut io = proc.io.lock();
+
+            let node = io.ioctx.as_ref().unwrap().find(None, path, true)?;
+            // TODO check access
+            io.files.push(node.open()?);
+
+            Ok(io.files.len() - 1)
+        }
+        // sys_read
+        3 => {
+            use crate::proc::Process;
+            use libcommon::Read;
+            let proc = Process::current();
+            let mut io = proc.io.lock();
+            let buf = validate_user_ptr(args[1], args[2])?;
+
+            io.files[args[0]].read(buf)
+        }
+        // sys_write
+        4 => {
+            use crate::proc::Process;
+            use libcommon::Write;
+            let proc = Process::current();
+            let mut io = proc.io.lock();
+            let buf = validate_user_ptr(args[1], args[2])?;
+
+            io.files[args[0]].write(buf)
+        }
         _ => panic!("Undefined system call: {}", num),
     }
 }
diff --git a/libusr/src/io.rs b/libusr/src/io.rs
new file mode 100644
index 0000000..a888811
--- /dev/null
+++ b/libusr/src/io.rs
@@ -0,0 +1,42 @@
+use crate::sys;
+use core::fmt;
+
+const STDOUT_FILENO: i32 = 0;
+
+#[macro_export]
+macro_rules! print {
+    ($($args:tt)+) => ($crate::io::_print(format_args!($($args)+)))
+}
+
+#[macro_export]
+macro_rules! println {
+    ($($args:tt)+) => (print!("{}\n", format_args!($($args)+)))
+}
+
+struct BufferWriter<'a> {
+    buf: &'a mut [u8],
+    pos: usize,
+}
+
+impl fmt::Write for BufferWriter<'_> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for byte in s.bytes() {
+            self.buf[self.pos] = byte;
+            self.pos += 1;
+        }
+        Ok(())
+    }
+}
+
+pub fn _print(args: fmt::Arguments) {
+    use core::fmt::Write;
+    static mut BUFFER: [u8; 4096] = [0; 4096];
+    let mut writer = BufferWriter {
+        buf: unsafe { &mut BUFFER },
+        pos: 0,
+    };
+    writer.write_fmt(args).ok();
+    unsafe {
+        sys::sys_write(STDOUT_FILENO, &BUFFER as *const _, writer.pos);
+    }
+}
diff --git a/libusr/src/lib.rs b/libusr/src/lib.rs
index 5e9648e..463ae5d 100644
--- a/libusr/src/lib.rs
+++ b/libusr/src/lib.rs
@@ -5,7 +5,8 @@ use core::panic::PanicInfo;
 
 pub mod mem;
 pub mod os;
-mod sys;
+pub mod io;
+pub mod sys;
 
 #[link_section = ".text._start"]
 #[no_mangle]
@@ -22,5 +23,7 @@ extern "C" fn _start(_arg: usize) -> ! {
 fn panic_handler(pi: &PanicInfo) -> ! {
     // TODO formatted messages
     trace!("Panic ocurred: {}", pi);
-    sys::sys_exit(-1);
+    unsafe {
+        sys::sys_exit(-1);
+    }
 }
diff --git a/libusr/src/os.rs b/libusr/src/os.rs
index afbc0ca..ac8e5f6 100644
--- a/libusr/src/os.rs
+++ b/libusr/src/os.rs
@@ -29,5 +29,7 @@ pub fn _trace(args: fmt::Arguments) {
         pos: 0,
     };
     writer.write_fmt(args).ok();
-    sys::sys_ex_debug_trace(unsafe { &BUFFER } as *const _, writer.pos);
+    unsafe {
+        sys::sys_ex_debug_trace(&BUFFER as *const _, writer.pos);
+    }
 }
diff --git a/libusr/src/sys.rs b/libusr/src/sys.rs
index ba68e54..4ebdc24 100644
--- a/libusr/src/sys.rs
+++ b/libusr/src/sys.rs
@@ -1,27 +1,49 @@
 macro_rules! syscall {
     ($num:expr, $a0:expr) => {{
         let mut res: usize = $a0;
-        unsafe {
-            asm!("svc #0", inout("x0") res, in("x8") $num, options(nostack));
-        }
+        asm!("svc #0",
+             inout("x0") res,
+             in("x8") $num, options(nostack));
         res
     }};
     ($num:expr, $a0:expr, $a1:expr) => {{
         let mut res: usize = $a0;
-        unsafe {
-            asm!("svc #0", inout("x0") res, in("x1") $a1, in("x8") $num, options(nostack));
-        }
+        asm!("svc #0",
+             inout("x0") res, in("x1") $a1,
+             in("x8") $num, options(nostack));
+        res
+    }};
+    ($num:expr, $a0:expr, $a1:expr, $a2:expr) => {{
+        let mut res: usize = $a0;
+        asm!("svc #0",
+             inout("x0") res, in("x1") $a1, in("x2") $a2,
+             in("x8") $num, options(nostack));
         res
     }};
 }
 
 #[inline(always)]
-pub fn sys_exit(status: i32) -> ! {
+pub unsafe fn sys_exit(status: i32) -> ! {
     syscall!(1, status as usize);
     loop {}
 }
 
 #[inline(always)]
-pub fn sys_ex_debug_trace(msg: *const u8, len: usize) -> usize {
+pub unsafe fn sys_ex_debug_trace(msg: *const u8, len: usize) -> usize {
     syscall!(120, msg as usize, len)
 }
+
+#[inline(always)]
+pub unsafe fn sys_open(pathname: *const u8, mode: u32, flags: u32) -> i32 {
+    syscall!(2, pathname as usize, mode as usize, flags as usize) as i32
+}
+
+#[inline(always)]
+pub unsafe fn sys_read(fd: i32, data: *mut u8, len: usize) -> isize {
+    syscall!(3, fd as usize, data as usize, len) as isize
+}
+
+#[inline(always)]
+pub unsafe fn sys_write(fd: i32, data: *const u8, len: usize) -> isize {
+    syscall!(4, fd as usize, data as usize, len) as isize
+}