diff --git a/kernel/libk/src/task/thread.rs b/kernel/libk/src/task/thread.rs
index 024d6c24..7466b3c8 100644
--- a/kernel/libk/src/task/thread.rs
+++ b/kernel/libk/src/task/thread.rs
@@ -350,6 +350,7 @@ impl Thread {
         if debug.tracer.is_some() {
             let timestamp = monotonic_time();
             debug.store_state(frame);
+            // log::info!("TRACE {payload:?}");
             self.events.trace.write(TraceEvent {
                 suspend,
                 timestamp,
@@ -513,7 +514,11 @@ impl Thread {
 
     /// Returns `true` if the thread is a tracee of given process
     pub fn is_tracee_of(&self, pid: ProcessId) -> bool {
-        self.debug.lock().tracer == Some(pid)
+        {
+            let tracer = self.debug.lock().tracer;
+            // log::info!("{:?}'s tracer: {:?}", self.id, tracer);
+            tracer == Some(pid)
+        }
     }
 
     pub fn attach_trace(&self, tracer: ProcessId) -> Result<(), Error> {
@@ -577,11 +582,13 @@ impl Thread {
             DebugControl::Detach => todo!(),
             DebugControl::Resume => {
                 let single_step = debug::Resume::load_request(input)?;
+                // log::info!("Resume single_step={single_step}");
                 self.resume(single_step);
                 debug::Resume::store_response(&(), buffer)
             }
             DebugControl::SetTraceFlags => {
                 let flags = debug::SetTraceFlags::load_request(buffer)?;
+                // log::info!("SetTraceFlags {flags:?}");
                 self.set_trace_flags(flags);
                 debug::SetTraceFlags::store_response(&(), buffer)
             }
diff --git a/kernel/src/main.rs b/kernel/src/main.rs
index c4c5e972..6cb33016 100644
--- a/kernel/src/main.rs
+++ b/kernel/src/main.rs
@@ -75,8 +75,10 @@ cfg_if::cfg_if! {
     if #[cfg(target_arch = "x86_64")] {
         extern crate ygg_driver_net_igbe;
     } else if #[cfg(target_arch = "aarch64")] {
+        extern crate ygg_driver_bsp_arm;
         extern crate ygg_driver_bsp_bcm283x;
     } else if #[cfg(target_arch = "riscv64")] {
+        extern crate ygg_driver_bsp_riscv;
         extern crate ygg_driver_bsp_jh7110;
 
         extern crate ygg_driver_net_stmmac;
diff --git a/userspace/Cargo.lock b/userspace/Cargo.lock
index 05b38b88..be156e1d 100644
--- a/userspace/Cargo.lock
+++ b/userspace/Cargo.lock
@@ -2970,6 +2970,8 @@ name = "strace"
 version = "0.1.0"
 dependencies = [
  "clap",
+ "cross",
+ "libc",
  "runtime",
 ]
 
diff --git a/userspace/lib/cross/src/debug.rs b/userspace/lib/cross/src/debug.rs
new file mode 100644
index 00000000..8b137891
--- /dev/null
+++ b/userspace/lib/cross/src/debug.rs
@@ -0,0 +1 @@
+
diff --git a/userspace/lib/cross/src/lib.rs b/userspace/lib/cross/src/lib.rs
index 89d46d45..c23721f2 100644
--- a/userspace/lib/cross/src/lib.rs
+++ b/userspace/lib/cross/src/lib.rs
@@ -4,6 +4,7 @@
 
 pub(crate) mod sys;
 
+pub mod debug;
 pub mod fs;
 pub mod io;
 pub mod mem;
diff --git a/userspace/lib/cross/src/process.rs b/userspace/lib/cross/src/process.rs
index 444cd2b0..283fb2d2 100644
--- a/userspace/lib/cross/src/process.rs
+++ b/userspace/lib/cross/src/process.rs
@@ -1,6 +1,64 @@
 use std::io;
 
+#[derive(Debug)]
+pub enum TraceEvent {
+    SyscallEntry(u64, [u64; 6]),
+    SyscallExit(i64),
+    Exited,
+}
+
+pub trait ChildTrace {
+    fn next_event(&mut self) -> io::Result<TraceEvent>;
+    fn resume(&mut self) -> io::Result<()>;
+    fn kill(&mut self) -> io::Result<()>;
+
+    unsafe fn peek_u8(&mut self, address: usize) -> io::Result<u8> {
+        let aligned = address & !7;
+        let shift = (address & 7) << 3;
+        let word = self.peek_u64(aligned)?;
+        Ok((word >> shift) as u8)
+    }
+    unsafe fn peek_u32(&mut self, address: usize) -> io::Result<u32> {
+        eprintln!("PEEK U32 @ {address:#x}");
+        assert_eq!(address & 3, 0);
+        let aligned = address & !7;
+        let shift = (address & 7) << 3;
+        let word = self.peek_u64(aligned)?;
+        Ok((word >> shift) as u32)
+    }
+    unsafe fn peek_u64(&mut self, address: usize) -> io::Result<u64>;
+
+    unsafe fn peek_bytes(&mut self, address: usize, buffer: &mut [u8]) -> io::Result<()> {
+        for i in 0..buffer.len() {
+            buffer[i] = self.peek_u8(address + i)?;
+        }
+        Ok(())
+    }
+
+    unsafe fn peek_cstr(&mut self, address: usize, buffer: &mut [u8]) -> io::Result<usize> {
+        let mut len = 0;
+        while len < buffer.len() - 1 {
+            let byte = self.peek_u8(address + len)?;
+            buffer[len] = byte;
+            if byte == 0 {
+                break;
+            }
+            len += 1;
+        }
+        Ok(len)
+    }
+
+    unsafe fn peek_usize(&mut self, address: usize) -> io::Result<usize> {
+        // FIXME I only support 64-bit archs
+        Ok(self.peek_u64(address)? as _)
+    }
+}
+
 pub trait CommandSpawnExt {
+    type ChildTrace: ChildTrace;
+
     fn create_session(&mut self) -> io::Result<&mut Self>;
     fn create_process_group(&mut self) -> io::Result<&mut Self>;
+    // TODO options for tracing across subchildren, etc
+    fn spawn_with_trace(&mut self) -> io::Result<Self::ChildTrace>;
 }
diff --git a/userspace/lib/cross/src/sys/unix/mod.rs b/userspace/lib/cross/src/sys/unix/mod.rs
index 59f5c33d..18ab8587 100644
--- a/userspace/lib/cross/src/sys/unix/mod.rs
+++ b/userspace/lib/cross/src/sys/unix/mod.rs
@@ -10,10 +10,12 @@ pub mod time;
 pub mod timer;
 
 use std::{
-    ffi::c_int,
+    ffi::{c_int, c_void},
     io,
+    mem::MaybeUninit,
     os::{fd::RawFd, unix::process::CommandExt},
     process::Command,
+    ptr::null_mut,
     sync::Mutex,
 };
 
@@ -26,7 +28,126 @@ pub use socket::{BorrowedAddressImpl, LocalPacketSocketImpl, OwnedAddressImpl};
 pub use term::RawStdinImpl;
 pub use timer::TimerFdImpl;
 
-use crate::process::CommandSpawnExt;
+use crate::process::{ChildTrace, CommandSpawnExt, TraceEvent};
+
+pub struct ChildTraceImpl {
+    child: libc::pid_t,
+}
+
+impl ChildTrace for ChildTraceImpl {
+    fn next_event(&mut self) -> io::Result<TraceEvent> {
+        let ev = loop {
+            unsafe {
+                let mut status = 0;
+                if libc::waitpid(self.child, &mut status, 0) < 0 {
+                    return Err(io::Error::last_os_error());
+                }
+                if libc::WIFSTOPPED(status) {
+                    let stopsig = libc::WSTOPSIG(status);
+                    if stopsig == libc::SIGTRAP | 0x80 {
+                        let mut syscall_info = MaybeUninit::<libc::ptrace_syscall_info>::zeroed();
+                        if libc::ptrace(
+                            libc::PTRACE_GET_SYSCALL_INFO,
+                            self.child,
+                            size_of::<libc::ptrace_syscall_info>(),
+                            syscall_info.as_mut_ptr(),
+                        ) < 0
+                        {
+                            return Err(io::Error::last_os_error());
+                        }
+
+                        let syscall_info = syscall_info.assume_init();
+                        match syscall_info.op {
+                            libc::PTRACE_SYSCALL_INFO_EXIT => {
+                                break TraceEvent::SyscallExit(syscall_info.u.exit.sval);
+                            }
+                            libc::PTRACE_SYSCALL_INFO_ENTRY => {
+                                break TraceEvent::SyscallEntry(
+                                    syscall_info.u.entry.nr,
+                                    syscall_info.u.entry.args,
+                                );
+                            }
+                            _ => self.resume()?,
+                        }
+                    } else if stopsig == libc::SIGTRAP {
+                        let event = (status >> 16) & 0xffff;
+                        eprintln!("event = {event}");
+                        match event {
+                            libc::PTRACE_EVENT_EXIT => {
+                                // Ignore
+                                eprintln!("PTRACE_EVENT_EXIT");
+                                self.resume()?;
+                            }
+                            libc::PTRACE_EVENT_VFORK => {
+                                eprintln!("PTRACE_EVENT_VFORK");
+                                self.resume()?;
+                            }
+                            libc::PTRACE_EVENT_EXEC => {
+                                // Ignore
+                                eprintln!("PTRACE_EVENT_EXEC");
+                                self.resume()?;
+                            }
+                            _ => todo!(),
+                        }
+                    } else {
+                        todo!("signum == {stopsig}");
+                    }
+                } else if libc::WIFEXITED(status) {
+                    break TraceEvent::Exited;
+                } else {
+                    todo!();
+                }
+            }
+        };
+
+        Ok(ev)
+    }
+
+    fn kill(&mut self) -> io::Result<()> {
+        todo!()
+    }
+
+    fn resume(&mut self) -> io::Result<()> {
+        if unsafe {
+            libc::ptrace(
+                libc::PTRACE_SYSCALL,
+                self.child,
+                null_mut::<c_void>(),
+                null_mut::<c_void>(),
+            )
+        } == 0
+        {
+            Ok(())
+        } else {
+            Err(io::Error::last_os_error())
+        }
+    }
+
+    unsafe fn peek_u64(&mut self, address: usize) -> io::Result<u64> {
+        libc::__errno_location().write_volatile(0);
+        let word = libc::ptrace(
+            libc::PTRACE_PEEKDATA,
+            self.child,
+            address,
+            null_mut::<c_void>(),
+        );
+        if libc::__errno_location().read_volatile() != 0 {
+            Err(io::Error::last_os_error())
+        } else {
+            Ok(word as _)
+        }
+    }
+}
+
+impl Drop for ChildTraceImpl {
+    fn drop(&mut self) {
+        let mut ignore = 0;
+        unsafe {
+            libc::ptrace(libc::PTRACE_DETACH, self.child);
+            libc::waitpid(self.child, &mut ignore, 0);
+        }
+    }
+}
 
 fn dummy_sigint() {}
 
@@ -61,6 +182,8 @@ pub fn clone_fd(fd: RawFd) -> io::Result<RawFd> {
 }
 
 impl CommandSpawnExt for Command {
+    type ChildTrace = ChildTraceImpl;
+
     fn create_process_group(&mut self) -> io::Result<&mut Self> {
         Ok(self.process_group(0))
     }
@@ -69,4 +192,54 @@ impl CommandSpawnExt for Command {
         // TODO
         Ok(self)
     }
+
+    fn spawn_with_trace(&mut self) -> io::Result<Self::ChildTrace> {
+        unsafe {
+            match libc::fork() {
+                0 => {
+                    // Child
+                    // if libc::ptrace(libc::PTRACE_TRACEME, libc::getpid()) != 0 {
+                    //     panic!("PTRACE_TRACEME: {}", io::Error::last_os_error());
+                    // }
+                    libc::raise(libc::SIGSTOP);
+                    panic!("exec error: {}", self.exec());
+                }
+                code if code < 0 => {
+                    // Error
+                    Err(io::Error::last_os_error())
+                }
+                pid => {
+                    let options = libc::PTRACE_O_TRACESYSGOOD | libc::PTRACE_O_TRACEEXEC;
+                    let mut ignore = 0;
+                    // Parent
+                    if libc::ptrace(
+                        libc::PTRACE_SEIZE,
+                        pid,
+                        null_mut::<c_void>(),
+                        null_mut::<c_void>(),
+                    ) != 0
+                    {
+                        // TODO waitpid child? kill child?
+                        eprintln!("PTRACE_SEIZE error");
+                        return Err(io::Error::last_os_error());
+                    }
+                    if libc::waitpid(pid, &mut ignore, 0) < 0 {
+                        return Err(io::Error::last_os_error());
+                    }
+                    if libc::ptrace(libc::PTRACE_SETOPTIONS, pid, null_mut::<c_void>(), options)
+                        != 0
+                    {
+                        return Err(io::Error::last_os_error());
+                    }
+                    libc::ptrace(
+                        libc::PTRACE_CONT,
+                        pid,
+                        null_mut::<c_void>(),
+                        null_mut::<c_void>(),
+                    );
+                    Ok(ChildTraceImpl { child: pid })
+                }
+            }
+        }
+    }
 }
diff --git a/userspace/lib/cross/src/sys/yggdrasil/mod.rs b/userspace/lib/cross/src/sys/yggdrasil/mod.rs
index 273688ac..6d295f4b 100644
--- a/userspace/lib/cross/src/sys/yggdrasil/mod.rs
+++ b/userspace/lib/cross/src/sys/yggdrasil/mod.rs
@@ -11,8 +11,20 @@ pub mod timer;
 
 use std::{
     io,
-    os::{fd::RawFd, yggdrasil::process::CommandExt},
-    process::Command,
+    mem::MaybeUninit,
+    os::{
+        fd::RawFd,
+        yggdrasil::process::{ChildExt, CommandExt},
+    },
+    process::{Child, Command},
+};
+
+use runtime::{
+    abi::{
+        arch::SavedFrame,
+        debug::{self, TraceFlags},
+    },
+    rt::{debug::debug_control, process::ThreadEvent},
 };
 
 pub use mem::{FileMappingImpl, SharedMemoryImpl};
@@ -24,7 +36,131 @@ pub use socket::{BorrowedAddressImpl, LocalPacketSocketImpl, OwnedAddressImpl};
 pub use term::RawStdinImpl;
 pub use timer::TimerFdImpl;
 
-use crate::process::CommandSpawnExt;
+use crate::process::{ChildTrace, CommandSpawnExt, TraceEvent};
+
+pub struct ChildTraceImpl {
+    #[allow(unused)]
+    child: Child,
+    buffer: [u8; 512],
+    tid: u32,
+}
+
+impl ChildTraceImpl {
+    fn attach(child: Child) -> io::Result<Self> {
+        let mut buffer = [0; 512];
+        let tid = child.main_thread_id()?;
+
+        debug_control::<debug::SetTraceFlags>(
+            tid,
+            &mut buffer,
+            &(TraceFlags::SYSCALL_ENTRY | TraceFlags::SYSCALL_EXIT),
+        )
+        .map_err(io::Error::from)
+        .unwrap();
+
+        Ok(Self { child, tid, buffer })
+    }
+
+    fn read_regs(&mut self) -> io::Result<SavedFrame> {
+        debug_control::<debug::GetRegisters>(self.tid, &mut self.buffer, &())
+            .map_err(io::Error::from)
+    }
+}
+
+#[cfg(any(rust_analyzer, target_arch = "aarch64"))]
+impl ChildTraceImpl {
+    fn read_syscall_entry(&mut self) -> io::Result<(u64, [u64; 6])> {
+        let frame = self.read_regs()?;
+        Ok((
+            frame.gp_regs[8] as _,
+            [
+                frame.gp_regs[0] as _,
+                frame.gp_regs[1] as _,
+                frame.gp_regs[2] as _,
+                frame.gp_regs[3] as _,
+                frame.gp_regs[4] as _,
+                frame.gp_regs[5] as _,
+            ],
+        ))
+    }
+
+    fn read_syscall_exit(&mut self) -> io::Result<u64> {
+        let frame = self.read_regs()?;
+        Ok(frame.gp_regs[0] as _)
+    }
+}
+
+#[cfg(any(rust_analyzer, target_arch = "x86_64"))]
+impl ChildTraceImpl {
+    fn read_syscall_entry(&mut self) -> io::Result<(u64, [u64; 6])> {
+        let frame = self.read_regs()?;
+        Ok((
+            frame.rax as _,
+            [
+                frame.rdi as _,
+                frame.rsi as _,
+                frame.rdx as _,
+                frame.r10 as _,
+                frame.r8 as _,
+                frame.r9 as _,
+            ],
+        ))
+    }
+
+    fn read_syscall_exit(&mut self) -> io::Result<u64> {
+        let frame = self.read_regs()?;
+        Ok(frame.rax as _)
+    }
+}
+
+impl ChildTrace for ChildTraceImpl {
+    unsafe fn peek_u64(&mut self, address: usize) -> io::Result<u64> {
+        let word = debug_control::<debug::ReadMemory>(self.tid, &mut self.buffer, &address)?;
+        Ok(word as _)
+    }
+
+    fn kill(&mut self) -> io::Result<()> {
+        todo!()
+    }
+
+    fn resume(&mut self) -> io::Result<()> {
+        debug_control::<debug::Resume>(self.tid, &mut self.buffer, &false).map_err(io::Error::from)
+    }
+
+    fn next_event(&mut self) -> io::Result<TraceEvent> {
+        loop {
+            let mut event = MaybeUninit::uninit();
+            unsafe { runtime::rt::sys::wait_thread(self.tid, &mut event) }
+                .map_err(io::Error::from)?;
+            let event = unsafe { event.assume_init() };
+
+            match event {
+                ThreadEvent::Trace(trace) => {
+                    let event = match trace.payload {
+                        debug::TraceEventPayload::SyscallEntry(_seq) => {
+                            let (nr, args) = self.read_syscall_entry()?;
+                            TraceEvent::SyscallEntry(nr, args)
+                        }
+                        debug::TraceEventPayload::SyscallExit(_seq) => {
+                            let status = self.read_syscall_exit()?;
+                            TraceEvent::SyscallExit(status as _)
+                        }
+                        debug::TraceEventPayload::SingleStep => {
+                            self.resume()?;
+                            continue;
+                        }
+                    };
+
+                    break Ok(event);
+                }
+                ThreadEvent::Exited => {
+                    // TODO status
+                    break Ok(TraceEvent::Exited);
+                }
+            }
+        }
+    }
+}
 
 pub fn set_sigint_handler(_handler: fn()) {}
 
@@ -45,6 +181,13 @@ pub fn clone_fd(fd: RawFd) -> io::Result<RawFd> {
 }
 
 impl CommandSpawnExt for Command {
+    type ChildTrace = ChildTraceImpl;
+
+    fn spawn_with_trace(&mut self) -> io::Result<Self::ChildTrace> {
+        unsafe { self.attach_tracing() };
+        self.spawn().and_then(ChildTraceImpl::attach)
+    }
+
     fn create_process_group(&mut self) -> io::Result<&mut Self> {
         let group = unsafe { runtime::rt::sys::create_process_group() };
         Ok(self.process_group(group))
diff --git a/userspace/tools/rdb/src/main.rs b/userspace/tools/rdb/src/main.rs
index 6e14af7d..7b48e39d 100644
--- a/userspace/tools/rdb/src/main.rs
+++ b/userspace/tools/rdb/src/main.rs
@@ -1,68 +1,3 @@
 #![feature(yggdrasil_os, if_let_guard)]
 
 fn main() {}
-// use std::{fmt::{LowerHex, Display}, io, path::PathBuf, process::Command};
-//
-// use clap::Parser;
-// use debugger::{Debugger, SymbolResolver};
-// use imp::TargetImpl;
-// use yggdrasil_abi::arch::SavedFrame;
-//
-// #[cfg(any(target_arch = "x86_64", target_arch = "x86", rust_analyzer))]
-// #[path = "x86.rs"]
-// pub mod imp;
-// #[cfg(any(target_arch = "aarch64", rust_analyzer))]
-// #[path = "aarch64.rs"]
-// pub mod imp;
-//
-// pub mod comm;
-// pub mod state;
-//
-// pub mod debugger;
-//
-// #[derive(thiserror::Error, Debug)]
-// pub enum Error {
-//     #[error("I/O error: {0}")]
-//     IoError(#[from] io::Error),
-//     #[error("Terminal error: {0}")]
-//     TermError(#[from] libterm::Error),
-//     #[error("Debug control error: {0:?}")]
-//     DebugError(yggdrasil_rt::Error),
-//     #[error("Invalid address: {0:?}")]
-//     InvalidAddress(String)
-// }
-//
-// pub trait Target {
-//     type Instruction;
-//     type InstructionFormatter: InstructionFormatter<Self::Instruction>;
-//     type Register: LowerHex;
-//
-//     fn disassemble(
-//         window: &[u8],
-//         ip: usize,
-//         limit: usize,
-//     ) -> Result<Vec<(usize, Self::Instruction)>, Error>;
-//     fn new_instruction_formatter(resolver: SymbolResolver) -> Self::InstructionFormatter;
-//
-//     fn register_list(frame: &SavedFrame, out: &mut Vec<(String, Self::Register)>);
-//     fn flags_register_as_display(frame: &SavedFrame) -> impl Display;
-//     fn real_ip(frame: &SavedFrame) -> usize;
-// }
-//
-// pub trait InstructionFormatter<I> {
-//     fn format_instruction(&mut self, insn: &I, out: &mut String);
-// }
-//
-// #[derive(Parser)]
-// struct Args {
-//     program: PathBuf,
-// }
-//
-// fn main() {
-//     let args = Args::parse();
-//
-//     let command = Command::new(&args.program);
-//     let debug: Debugger<TargetImpl> = Debugger::from_command(&args.program, command).unwrap();
-//
-//     debug.run().unwrap();
-// }
diff --git a/userspace/tools/strace/Cargo.toml b/userspace/tools/strace/Cargo.toml
index 431169d3..9754783b 100644
--- a/userspace/tools/strace/Cargo.toml
+++ b/userspace/tools/strace/Cargo.toml
@@ -4,9 +4,19 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-runtime.workspace = true
+cross.workspace = true
 
 clap.workspace = true
 
+[target.'cfg(target_os = "yggdrasil")'.dependencies]
+runtime.workspace = true
+
+[target.'cfg(target_os = "linux")'.dependencies]
+libc = "*"
+
+[dev-dependencies]
+runtime.workspace = true
+libc = "*"
+
 [lints]
 workspace = true
diff --git a/userspace/tools/strace/src/definition/linux/mod.rs b/userspace/tools/strace/src/definition/linux/mod.rs
new file mode 100644
index 00000000..0fdb2916
--- /dev/null
+++ b/userspace/tools/strace/src/definition/linux/mod.rs
@@ -0,0 +1,175 @@
+#[cfg(any(rust_analyzer, target_arch = "x86_64"))]
+#[path = "x86_64.rs"]
+pub mod imp;
+
+use std::fmt;
+
+pub use imp::*;
+use libc::{c_int, c_uint};
+
+macro_rules! impl_ioctls {
+    ($f:expr, $v:expr, $ty:ty, [$($ioctl:ident),* $(,)?]) => {{
+        #[allow(unreachable_patterns)]
+        let v = match $v as $ty {
+            $(libc::$ioctl => stringify!($ioctl),)*
+            _ => return write!($f, "{:#x}", $v),
+        };
+        write!($f, "{v}")
+    }};
+}
+
+fn print_ioctl<W: fmt::Write>(f: &mut W, v: c_uint) -> fmt::Result {
+    impl_ioctls!(
+        f,
+        v,
+        u64,
+        [
+            TCGETS,
+            TCSETS,
+            TCSETSW,
+            TCSETSF,
+            TCGETA,
+            TCSETA,
+            TCSETAW,
+            TCSETAF,
+            TCSBRK,
+            TCXONC,
+            TCFLSH,
+            TIOCEXCL,
+            TIOCNXCL,
+            TIOCSCTTY,
+            TIOCGPGRP,
+            TIOCSPGRP,
+            TIOCOUTQ,
+            TIOCSTI,
+            TIOCGWINSZ,
+            TIOCSWINSZ,
+            TIOCMGET,
+            TIOCMBIS,
+            TIOCMBIC,
+            TIOCMSET,
+            TIOCGSOFTCAR,
+            TIOCSSOFTCAR,
+            FIONREAD,
+            TIOCLINUX,
+            TIOCCONS,
+            TIOCGSERIAL,
+            TIOCSSERIAL,
+            TIOCPKT,
+            FIONBIO,
+            TIOCNOTTY,
+            TIOCSETD,
+            TIOCGETD,
+            TCSBRKP,
+            TIOCSBRK,
+            TIOCCBRK,
+            TIOCGSID,
+            TCGETS2,
+            TCSETS2,
+            TCSETSW2,
+            TCSETSF2,
+            TIOCGRS485,
+            TIOCSRS485,
+            TIOCGPTN,
+            TIOCSPTLCK,
+            TIOCGDEV,
+            TCGETX,
+            TCSETX,
+            TCSETXF,
+            TCSETXW,
+            TIOCSIG,
+            TIOCVHANGUP,
+            TIOCGPKT,
+            TIOCGPTLCK,
+            TIOCGEXCL,
+            TIOCGPTPEER,
+            FIONCLEX,
+            FIOCLEX,
+            FIOASYNC,
+            TIOCSERCONFIG,
+            TIOCSERGWILD,
+            TIOCSERSWILD,
+            TIOCGLCKTRMIOS,
+            TIOCSLCKTRMIOS,
+            TIOCSERGSTRUCT,
+            TIOCSERGETLSR,
+            TIOCSERGETMULTI,
+            TIOCSERSETMULTI,
+            TIOCMIWAIT,
+            TIOCGICOUNT,
+        ]
+    )
+}
+
+fn print_prctl<W: fmt::Write>(f: &mut W, c: c_int) -> fmt::Result {
+    impl_ioctls!(
+        f,
+        c,
+        c_int,
+        [
+            PR_SET_PDEATHSIG,
+            PR_GET_PDEATHSIG,
+            PR_GET_DUMPABLE,
+            PR_SET_DUMPABLE,
+            PR_GET_UNALIGN,
+            PR_SET_UNALIGN,
+            PR_GET_KEEPCAPS,
+            PR_SET_KEEPCAPS,
+            PR_GET_FPEMU,
+            PR_SET_FPEMU,
+            PR_GET_FPEXC,
+            PR_SET_FPEXC,
+            PR_GET_TIMING,
+            PR_SET_TIMING,
+            PR_SET_NAME,
+            PR_GET_NAME,
+            PR_GET_ENDIAN,
+            PR_SET_ENDIAN,
+            PR_GET_SECCOMP,
+            PR_SET_SECCOMP,
+            PR_CAPBSET_READ,
+            PR_CAPBSET_DROP,
+            PR_GET_TSC,
+            PR_SET_TSC,
+            PR_GET_SECUREBITS,
+            PR_SET_SECUREBITS,
+            PR_SET_TIMERSLACK,
+            PR_GET_TIMERSLACK,
+            PR_TASK_PERF_EVENTS_DISABLE,
+            PR_TASK_PERF_EVENTS_ENABLE,
+            PR_MCE_KILL,
+            PR_SET_MM,
+            PR_SET_PTRACER,
+            PR_SET_CHILD_SUBREAPER,
+            PR_GET_CHILD_SUBREAPER,
+            PR_SET_NO_NEW_PRIVS,
+            PR_GET_NO_NEW_PRIVS,
+            PR_GET_TID_ADDRESS,
+            PR_SET_THP_DISABLE,
+            PR_GET_THP_DISABLE,
+            PR_MPX_ENABLE_MANAGEMENT,
+            PR_MPX_DISABLE_MANAGEMENT,
+            PR_SET_FP_MODE,
+            PR_GET_FP_MODE,
+            PR_CAP_AMBIENT,
+            PR_GET_SPECULATION_CTRL,
+            PR_SET_SPECULATION_CTRL,
+            PR_SCHED_CORE,
+            PR_SET_MDWE,
+            PR_GET_MDWE,
+            PR_SET_VMA,
+        ]
+    )
+}
+
+fn print_access_mode<W: fmt::Write>(f: &mut W, mode: c_int) -> fmt::Result {
+    let s = match mode {
+        libc::F_OK => "F_OK",
+        libc::W_OK => "W_OK",
+        libc::R_OK => "R_OK",
+        libc::X_OK => "X_OK",
+        _ => return write!(f, "{mode:#x}"),
+    };
+
+    write!(f, "{s}")
+}
diff --git a/userspace/tools/strace/src/definition/linux/x86_64.rs b/userspace/tools/strace/src/definition/linux/x86_64.rs
new file mode 100644
index 00000000..22b6175c
--- /dev/null
+++ b/userspace/tools/strace/src/definition/linux/x86_64.rs
@@ -0,0 +1,123 @@
+use std::{ffi::c_void, fmt};
+
+use cross::process::ChildTrace;
+use libc::{c_char, c_int, c_long, c_uint, c_ulong};
+
+use crate::definition::{
+    imp::{print_access_mode, print_ioctl, print_prctl},
+    print_cstring, PrintSyscallArgument, Syscall,
+};
+
+pub enum SyscallArgument {
+    Fd(c_int),
+    MaybeFd(c_int),
+    Bytes(*const c_char),
+    BytesMut(*const c_char),
+    Size(usize),
+    Filename(*const c_char),
+    OpenOptions(c_int),
+    FileMode(c_int),
+    Ptr(*const c_void),
+    Long(c_long),
+    ULong(c_ulong),
+    Int(c_int),
+    UInt(c_uint),
+    Whence(c_int),
+    Off(libc::off_t),
+    LOff(libc::loff_t),
+    IoctlCmd(c_uint),
+    PrctlCmd(c_int),
+    AccessMode(c_int),
+    AtFd(c_int),
+}
+
+impl PrintSyscallArgument for SyscallArgument {
+    fn print_syscall_argument<W: fmt::Write, T: ChildTrace>(&self, f: &mut W, trace: &mut T) {
+        match self {
+            Self::Fd(libc::STDIN_FILENO) => write!(f, "STDIN_FILENO"),
+            Self::Fd(libc::STDOUT_FILENO) => write!(f, "STDOUT_FILENO"),
+            Self::Fd(libc::STDERR_FILENO) => write!(f, "STDERR_FILENO"),
+            Self::Fd(fd) => write!(f, "{fd}"),
+            Self::MaybeFd(-1) => write!(f, "<none>"),
+            Self::MaybeFd(fd) => write!(f, "{fd}"),
+            Self::Bytes(bytes) => write!(f, "{bytes:p}"),
+            Self::BytesMut(bytes) => write!(f, "{bytes:p}"),
+            Self::Size(size) if *size <= 999 => write!(f, "{size}"),
+            Self::Size(size) => write!(f, "{size:#x}"),
+            Self::Filename(filename) => print_cstring(f, trace, filename.addr()),
+            Self::OpenOptions(opts) => write!(f, "{opts:#x}"),
+            Self::FileMode(mode) => write!(f, "0{mode:o}"),
+            Self::Ptr(ptr) => write!(f, "{ptr:p}"),
+            Self::Long(val) => write!(f, "{val}"),
+            Self::ULong(val) => write!(f, "{val}"),
+            Self::Int(val) => write!(f, "{val}"),
+            Self::UInt(val) => write!(f, "{val}"),
+            Self::Whence(libc::SEEK_SET) => write!(f, "SEEK_SET"),
+            Self::Whence(libc::SEEK_CUR) => write!(f, "SEEK_CUR"),
+            Self::Whence(libc::SEEK_END) => write!(f, "SEEK_END"),
+            Self::Whence(w) => write!(f, "{w}"),
+            Self::Off(off) => write!(f, "{off}"),
+            Self::LOff(off) => write!(f, "{off}"),
+            &Self::IoctlCmd(v) => print_ioctl(f, v),
+            &Self::PrctlCmd(v) => print_prctl(f, v),
+            &Self::AccessMode(m) => print_access_mode(f, m),
+            Self::AtFd(libc::AT_FDCWD) => write!(f, "AT_FDCWD"),
+            Self::AtFd(fd) => write!(f, "{fd}"),
+        }
+        .ok();
+    }
+}
+
+macro_rules! impl_syscall_args {
+    ($input:expr, [$($collect:expr),*], $i:expr, [$arg:ident, $($tail:ident),+]) => {
+        impl_syscall_args!($input, [$($collect,)* (SyscallArgument::$arg($input[$i] as _))], $i + 1, [$($tail),+])
+    };
+    ($input:expr, [$($collect:expr),*], $i:expr, [$arg:ident]) => {
+        vec![$($collect,)* (SyscallArgument::$arg($input[$i] as _))]
+    };
+    ($input:expr, [], $i:expr, []) => {
+        vec![]
+    };
+}
+
+macro_rules! impl_syscall_parse {
+    ($(
+        $nr:literal => $name:ident ( $($arg:ident),* )
+    ),+ $(,)?) => {
+        pub fn parse_syscall(nr: u64, args: &[u64]) -> Option<Syscall> {
+            Some(match nr {
+                $($nr => Syscall(
+                    stringify!($name),
+                    impl_syscall_args!(args, [], 0, [$($arg),*])
+                ),)+
+                _ => return None,
+            })
+        }
+    };
+}
+
+impl_syscall_parse!(
+    0 => read(Fd, BytesMut, Size),
+    1 => write(Fd, Bytes, Size),
+    2 => open(Filename, OpenOptions, FileMode),
+    3 => close(Fd),
+    4 => stat(Filename, BytesMut),
+    5 => fstat(Fd, BytesMut),
+    6 => lstat(Filename, BytesMut),
+    7 => poll(Ptr, ULong, Long),
+    8 => lseek(Fd, Off, Whence),
+    9 => mmap(Ptr, ULong, ULong, ULong, MaybeFd, ULong),
+    10 => mprotect(Ptr, Size, ULong),
+    11 => munmap(Ptr, Size),
+    12 => brk(Ptr),
+    // TODO rt_...
+    16 => ioctl(Fd, IoctlCmd, ULong),
+    17 => pread64(Fd, BytesMut, Size, LOff),
+    21 => access(Filename, AccessMode),
+    157 => prctl(PrctlCmd, ULong, ULong, ULong),
+    218 => set_tid_address(Ptr),
+    334 => rseq(Ptr, UInt, Int, UInt),
+    257 => openat(AtFd, Filename, OpenOptions, FileMode),
+    262 => newfstatat(AtFd, Filename, Ptr, Int),
+    24 => sched_yield(),
+);
diff --git a/userspace/tools/strace/src/definition/mod.rs b/userspace/tools/strace/src/definition/mod.rs
new file mode 100644
index 00000000..730f32fd
--- /dev/null
+++ b/userspace/tools/strace/src/definition/mod.rs
@@ -0,0 +1,67 @@
+use std::fmt;
+
+use cross::process::ChildTrace;
+
+#[cfg(any(rust_analyzer, target_os = "linux"))]
+#[path = "linux/mod.rs"]
+pub mod imp;
+#[cfg(any(rust_analyzer, target_os = "yggdrasil"))]
+#[path = "yggdrasil.rs"]
+pub mod imp;
+
+pub use imp::*;
+
+pub trait PrintSyscallArgument {
+    fn print_syscall_argument<W: fmt::Write, T: ChildTrace>(&self, f: &mut W, trace: &mut T);
+}
+
+pub struct Syscall(pub &'static str, pub Vec<SyscallArgument>);
+
+impl Syscall {
+    pub fn print<W: fmt::Write, T: ChildTrace>(&self, f: &mut W, trace: &mut T) {
+        write!(f, "{}(", self.0).ok();
+        for (i, arg) in self.1.iter().enumerate() {
+            if i != 0 {
+                write!(f, ", ").ok();
+            }
+            arg.print_syscall_argument(f, trace);
+        }
+        write!(f, ")").ok();
+    }
+}
+
+pub fn print_string<W: fmt::Write, T: ChildTrace>(
+    f: &mut W,
+    trace: &mut T,
+    address: usize,
+    len: usize,
+) -> fmt::Result {
+    let mut buffer = [0; 64];
+    let len = len.min(buffer.len());
+    if let Ok(()) = unsafe { trace.peek_bytes(address, &mut buffer[..len]) } {
+        if let Ok(s) = std::str::from_utf8(&buffer[..len]) {
+            write!(f, "{s:?}")
+        } else {
+            todo!()
+        }
+    } else {
+        write!(f, "<error str {address:#x}>")
+    }
+}
+
+pub fn print_cstring<W: fmt::Write, T: ChildTrace>(
+    f: &mut W,
+    trace: &mut T,
+    address: usize,
+) -> fmt::Result {
+    let mut buffer = [0; 64];
+    if let Ok(len) = unsafe { trace.peek_cstr(address, &mut buffer) } {
+        if let Ok(s) = std::str::from_utf8(&buffer[..len]) {
+            write!(f, "{s:?}")
+        } else {
+            todo!()
+        }
+    } else {
+        write!(f, "<error str {address:#x}>")
+    }
+}
diff --git a/userspace/tools/strace/src/definition/yggdrasil.rs b/userspace/tools/strace/src/definition/yggdrasil.rs
new file mode 100644
index 00000000..4c363954
--- /dev/null
+++ b/userspace/tools/strace/src/definition/yggdrasil.rs
@@ -0,0 +1,335 @@
+use std::fmt;
+
+use cross::process::ChildTrace;
+use runtime::{abi::SyscallFunction, abi_lib::SyscallRegister, rt::io::RawFd};
+
+use crate::definition::{print_string, PrintSyscallArgument, Syscall};
+
+pub enum SyscallArgument {
+    Bytes(u64, u64),
+    BytesMut(u64, u64),
+    MaybePtr(u64),
+    Fd(u64),
+    OptionFd(u64),
+    Ptr(u64),
+    Size(u64),
+    U64(u64),
+    I64(i64),
+    U32(u32),
+    I32(i32),
+    PtrSystemTime(u64),
+    ClockType(u64),
+    Filename(u64, u64),
+}
+
+pub enum ArgType {
+    Bytes,
+    BytesMut,
+    MaybePtr,
+    Fd,
+    OptionFd,
+    Ptr,
+    Size,
+    U64,
+    I64,
+    U32,
+    I32,
+    PtrSystemTime,
+    ClockType,
+    Filename,
+}
+
+struct SyscallDefinition(SyscallFunction, &'static str, &'static [ArgType]);
+
+impl PrintSyscallArgument for SyscallArgument {
+    fn print_syscall_argument<W: fmt::Write, T: ChildTrace>(&self, f: &mut W, trace: &mut T) {
+        match self {
+            &Self::MaybePtr(0) => write!(f, "None"),
+            Self::Fd(fd) => {
+                let fd = unsafe { RawFd::from_raw(*fd as _) };
+                match fd {
+                    RawFd::STDIN => write!(f, "STDIN"),
+                    RawFd::STDOUT => write!(f, "STDOUT"),
+                    RawFd::STDERR => write!(f, "STDERR"),
+                    _ => write!(f, "{fd:?}"),
+                }
+            }
+            Self::OptionFd(fd) => match Option::<RawFd>::from_syscall_register(*fd as _) {
+                Some(fd) => write!(f, "Some({fd:?})"),
+                None => write!(f, "None"),
+            },
+            Self::MaybePtr(addr) => write!(f, "Some({addr:#x})"),
+            Self::Ptr(ptr) => write!(f, "{ptr:#x}"),
+            Self::U64(val) => write!(f, "{val}"),
+            Self::I64(val) => write!(f, "{val}"),
+            Self::U32(val) => write!(f, "{val}"),
+            Self::I32(val) => write!(f, "{val}"),
+            Self::Size(val) => write!(f, "{val}"),
+            Self::Bytes(addr, len) => write!(f, "&[{addr:#x}; {len}]"),
+            Self::BytesMut(addr, len) => write!(f, "&mut [{addr:#x}; {len}]"),
+            Self::PtrSystemTime(ptr) => write!(f, "{ptr:#x}"),
+            Self::ClockType(1) => write!(f, "RealTime"),
+            Self::ClockType(2) => write!(f, "Monotonic"),
+            Self::ClockType(v) => write!(f, "{v}"),
+            Self::Filename(ptr, len) => print_string(f, trace, *ptr as _, *len as _),
+        }
+        .ok();
+    }
+}
+
+const DEFS: &[SyscallDefinition] = &const {
+    use ArgType::*;
+    [
+        SyscallDefinition(SyscallFunction::GetRandom, "get_random", &[BytesMut]),
+        SyscallDefinition(
+            SyscallFunction::GetClock,
+            "get_clock",
+            &[ClockType, PtrSystemTime],
+        ),
+        SyscallDefinition(
+            SyscallFunction::SetClock,
+            "set_clock",
+            &[ClockType, PtrSystemTime],
+        ),
+        SyscallDefinition(SyscallFunction::Mount, "mount", &[Ptr]), // TODO
+        SyscallDefinition(SyscallFunction::Unmount, "unmount", &[Ptr]), // TODO
+        SyscallDefinition(SyscallFunction::LoadModule, "load_module", &[Filename]),
+        SyscallDefinition(
+            SyscallFunction::FilesystemControl,
+            "filesystem_control",
+            &[OptionFd, U32, Size],
+        ),
+        SyscallDefinition(
+            SyscallFunction::GetSystemInfo,
+            "get_system_info",
+            &[U32, BytesMut],
+        ), // TODO
+        // Memory management
+        SyscallDefinition(
+            SyscallFunction::MapMemory,
+            "map_memory",
+            &[MaybePtr, Size, U32, Ptr],
+        ),
+        SyscallDefinition(SyscallFunction::UnmapMemory, "unmap_memory", &[Ptr, Size]),
+        // Process/thread management
+        SyscallDefinition(
+            SyscallFunction::CreateProcessGroup,
+            "create_process_group",
+            &[],
+        ),
+        SyscallDefinition(
+            SyscallFunction::GetProcessGroupId,
+            "get_process_group_id",
+            &[],
+        ),
+        SyscallDefinition(SyscallFunction::ExitProcess, "exit_process", &[U64]), // TODO
+        SyscallDefinition(SyscallFunction::SpawnProcess, "spawn_process", &[Ptr]), // TODO
+        SyscallDefinition(
+            SyscallFunction::WaitProcess,
+            "wait_process",
+            &[Ptr, Ptr, U32],
+        ), // TODO
+        SyscallDefinition(SyscallFunction::GetPid, "get_pid", &[]),
+        SyscallDefinition(SyscallFunction::GetTid, "get_tid", &[]),
+        SyscallDefinition(SyscallFunction::SpawnThread, "spawn_thread", &[Ptr]), // TODO
+        SyscallDefinition(SyscallFunction::ExitThread, "exit_thread", &[]),
+        SyscallDefinition(SyscallFunction::WaitThread, "wait_thread", &[U32, Ptr]), // TODO
+        SyscallDefinition(
+            SyscallFunction::GetThreadOption,
+            "get_thread_option",
+            &[U32, BytesMut],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::SetThreadOption,
+            "set_thread_option",
+            &[U32, Bytes],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::GetProcessOption,
+            "get_process_option",
+            &[U32, U32, BytesMut],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::SetProcessOption,
+            "set_process_option",
+            &[U32, U32, Bytes],
+        ), // TODO
+        SyscallDefinition(SyscallFunction::Nanosleep, "nanosleep", &[Ptr, Ptr]),    // TODO
+        SyscallDefinition(SyscallFunction::ExitSignal, "exit_signal", &[Ptr]),      // TODO
+        SyscallDefinition(SyscallFunction::SendSignal, "send_signal", &[U32, U32]), // TODO
+        SyscallDefinition(SyscallFunction::Mutex, "mutex", &[Ptr, Ptr]),            // TODO
+        SyscallDefinition(SyscallFunction::StartSession, "start_session", &[]),
+        // I/O
+        SyscallDefinition(
+            SyscallFunction::Open,
+            "open",
+            &[OptionFd, Filename, U32, U32],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::CheckAccess,
+            "check_access",
+            &[OptionFd, Filename, U32],
+        ), // TODO
+        SyscallDefinition(SyscallFunction::Close, "close", &[Fd]),
+        SyscallDefinition(SyscallFunction::Write, "write", &[Fd, Bytes]),
+        SyscallDefinition(SyscallFunction::Read, "read", &[Fd, BytesMut]),
+        SyscallDefinition(SyscallFunction::Seek, "seek", &[Fd, U32, Ptr]), // TODO
+        SyscallDefinition(SyscallFunction::Truncate, "truncate", &[Fd, U64]), // TODO
+        SyscallDefinition(SyscallFunction::Fsync, "fsync", &[Fd, U32]),    // TODO
+        SyscallDefinition(SyscallFunction::ReadAt, "read_at", &[Fd, U64, BytesMut]),
+        SyscallDefinition(SyscallFunction::WriteAt, "write_at", &[Fd, U64, Bytes]),
+        SyscallDefinition(
+            SyscallFunction::GetFileOption,
+            "get_file_option",
+            &[Fd, U32, BytesMut],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::SetFileOption,
+            "set_file_option",
+            &[Fd, U32, Bytes],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::OpenDirectory,
+            "open_directory",
+            &[OptionFd, Filename],
+        ),
+        SyscallDefinition(
+            SyscallFunction::ReadDirectoryEntries,
+            "read_directory_entries",
+            &[Fd, Ptr, Size],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::CreateDirectory,
+            "create_directory",
+            &[OptionFd, Filename, U32],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::ReadLink,
+            "read_link",
+            &[OptionFd, Filename, BytesMut],
+        ),
+        SyscallDefinition(
+            SyscallFunction::Remove,
+            "remove",
+            &[OptionFd, Filename, U32],
+        ), // TODO
+        SyscallDefinition(SyscallFunction::Rename, "rename", &[Ptr]), // TODO
+        SyscallDefinition(SyscallFunction::CloneFd, "clone_fd", &[Fd, OptionFd]),
+        SyscallDefinition(
+            SyscallFunction::UpdateMetadata,
+            "update_metadata",
+            &[OptionFd, Filename, Ptr],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::GetMetadata,
+            "get_metadata",
+            &[OptionFd, Filename, Ptr, U32],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::DeviceRequest,
+            "device_request",
+            &[Fd, U32, BytesMut, Size],
+        ), // TODO
+        SyscallDefinition(SyscallFunction::CreateTimer, "create_timer", &[U32]), // TODO
+        SyscallDefinition(SyscallFunction::CreatePid, "create_pid", &[Ptr, U32]), // TODO
+        SyscallDefinition(SyscallFunction::CreatePty, "create_pty", &[Ptr, Ptr, Ptr]), // TODO
+        SyscallDefinition(
+            SyscallFunction::CreateSharedMemory,
+            "create_shared_memory",
+            &[Size],
+        ),
+        SyscallDefinition(
+            SyscallFunction::CreatePollChannel,
+            "create_poll_channel",
+            &[],
+        ),
+        SyscallDefinition(SyscallFunction::CreatePipe, "create_pipe", &[Ptr]), // TODO
+        SyscallDefinition(
+            SyscallFunction::PollChannelWait,
+            "poll_channel_wait",
+            &[Fd, Ptr, U32, Ptr],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::PollChannelControl,
+            "poll_channel_control",
+            &[Fd, U32, Fd],
+        ), // TODO
+        // Network
+        SyscallDefinition(SyscallFunction::CreateSocket, "create_socket", &[U32]), // TODO
+        SyscallDefinition(SyscallFunction::Bind, "bind", &[Fd, Bytes]),            // TODO
+        SyscallDefinition(SyscallFunction::Listen, "listen", &[Fd]),
+        SyscallDefinition(SyscallFunction::Connect, "connect", &[Fd, Bytes]), // TODO
+        SyscallDefinition(SyscallFunction::Accept, "accept", &[Fd, MaybePtr]), // TODO
+        SyscallDefinition(SyscallFunction::Shutdown, "shutdown", &[Fd, U32]), // TODO
+        SyscallDefinition(SyscallFunction::SendTo, "send_to", &[Fd, Bytes, MaybePtr]), // TODO
+        SyscallDefinition(
+            SyscallFunction::ReceiveFrom,
+            "receive_from",
+            &[Fd, BytesMut, MaybePtr],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::GetSocketOption,
+            "get_socket_option",
+            &[Fd, U32, BytesMut],
+        ), // TODO
+        SyscallDefinition(
+            SyscallFunction::SetSocketOption,
+            "set_socket_option",
+            &[Fd, U32, Bytes],
+        ), // TODO
+        SyscallDefinition(SyscallFunction::SendMessage, "send_message", &[Fd, Ptr]), // TODO
+        SyscallDefinition(
+            SyscallFunction::ReceiveMessage,
+            "receive_message",
+            &[Fd, Ptr],
+        ), // TODO
+        // C compat
+        SyscallDefinition(SyscallFunction::Fork, "fork", &[]),
+        SyscallDefinition(SyscallFunction::Execve, "execve", &[Ptr]), // TODO
+        // Debugging
+        SyscallDefinition(SyscallFunction::DebugTrace, "debug_trace", &[U32, Filename]), // TODO
+        SyscallDefinition(
+            SyscallFunction::DebugControl,
+            "debug_control",
+            &[U32, U32, BytesMut, Size],
+        ), // TODO
+    ]
+};
+
+impl SyscallDefinition {
+    fn parse(&self, args: &[u64]) -> Syscall {
+        let mut res = vec![];
+        let mut pos = 0;
+        for arg_def in self.2.iter() {
+            use SyscallArgument::*;
+
+            let (a, l) = match arg_def {
+                ArgType::MaybePtr => (MaybePtr(args[pos]), 1),
+                ArgType::Bytes => (Bytes(args[pos], args[pos + 1]), 2),
+                ArgType::BytesMut => (BytesMut(args[pos], args[pos + 1]), 2),
+                ArgType::Fd => (Fd(args[pos]), 1),
+                ArgType::OptionFd => (OptionFd(args[pos]), 1),
+                ArgType::Ptr => (Ptr(args[pos]), 1),
+                ArgType::Size => (Size(args[pos]), 1),
+                ArgType::U64 => (U64(args[pos]), 1),
+                ArgType::I64 => (I64(args[pos] as _), 1),
+                ArgType::U32 => (U32(args[pos] as _), 1),
+                ArgType::I32 => (I32(args[pos] as _), 1),
+                ArgType::PtrSystemTime => (PtrSystemTime(args[pos]), 1),
+                ArgType::ClockType => (ClockType(args[pos]), 1),
+                ArgType::Filename => (Filename(args[pos], args[pos + 1]), 2),
+            };
+
+            pos += l;
+            res.push(a);
+        }
+
+        Syscall(self.1, res)
+    }
+}
+
+pub fn parse_syscall(nr: u64, args: &[u64]) -> Option<Syscall> {
+    let func = SyscallFunction::try_from(nr as usize).ok()?;
+    let def = DEFS.iter().find(|e| e.0 == func)?;
+    Some(def.parse(args))
+}
diff --git a/userspace/tools/strace/src/main.rs b/userspace/tools/strace/src/main.rs
index c87e1b35..bf1aa65b 100644
--- a/userspace/tools/strace/src/main.rs
+++ b/userspace/tools/strace/src/main.rs
@@ -1,36 +1,68 @@
-#![feature(rustc_private, yggdrasil_os, let_chains)]
-
+#![feature(rustc_private)]
 use std::{
-    io,
     process::{Command, ExitCode},
+    sync::atomic::{AtomicBool, Ordering},
 };
 
 use clap::Parser;
-use tracer::CommandTracer;
+use cross::{
+    process::{ChildTrace, CommandSpawnExt, TraceEvent},
+    signal,
+};
 
-pub mod format;
-pub mod tracer;
+use crate::definition::parse_syscall;
+
+pub mod definition;
 
 #[derive(Debug, Parser)]
 struct Args {
-    command: String,
+    program: String,
     args: Vec<String>,
 }
 
-fn run(args: &Args) -> io::Result<()> {
-    let mut command = Command::new(&args.command);
-    command.args(&args.args);
-    let tracer = CommandTracer::spawn(command)?;
-    tracer.run(format::format_syscall)
-}
-
 fn main() -> ExitCode {
     let args = Args::parse();
-    match run(&args) {
-        Ok(()) => ExitCode::SUCCESS,
-        Err(error) => {
-            eprintln!("{}: {error}", args.command);
-            ExitCode::FAILURE
+
+    static ABORT: AtomicBool = AtomicBool::new(false);
+
+    signal::set_sigint_handler(|| {
+        ABORT.store(true, Ordering::Release);
+        eprintln!("SIGINT");
+    });
+    let mut child = Command::new(args.program)
+        .args(args.args)
+        .spawn_with_trace()
+        .unwrap();
+
+    let mut last_syscall: Option<(u64, [u64; 6])> = None;
+
+    while !ABORT.load(Ordering::Relaxed) {
+        let event = child.next_event().unwrap();
+        match event {
+            TraceEvent::Exited => {
+                eprintln!("Exit");
+                break;
+            }
+            TraceEvent::SyscallExit(ret) => match last_syscall {
+                Some((nr, args)) => {
+                    let call = parse_syscall(nr, &args);
+                    if let Some(call) = call {
+                        let mut s = String::new();
+                        call.print(&mut s, &mut child);
+                        eprintln!("{s} -> {ret}");
+                    } else {
+                        eprintln!("syscall {nr} {args:?} -> {ret}");
+                    }
+                }
+                None => {
+                    eprintln!("??? -> {ret}");
+                }
+            },
+            TraceEvent::SyscallEntry(nr, args) => {
+                last_syscall = Some((nr, args));
+            }
         }
+        child.resume().ok();
     }
+    ExitCode::SUCCESS
 }