diff --git a/src/header/bits_eventfd/mod.rs b/src/header/bits_eventfd/mod.rs
new file mode 100644
index 0000000000..87c8d941fb
--- /dev/null
+++ b/src/header/bits_eventfd/mod.rs
@@ -0,0 +1,4 @@
+//! `bits/eventfd.h` — eventfd counter type.
+
+use crate::platform::types::uint64_t;
+pub type eventfd_t = uint64_t;
diff --git a/src/header/mod.rs b/src/header/mod.rs
index 6e65c4b23e..c078fbe1c8 100644
--- a/src/header/mod.rs
+++ b/src/header/mod.rs
@@ -5,6 +5,7 @@ pub mod _fenv;
 pub mod arpa_inet;
 pub mod assert;
 pub mod bits_arpainet;
+pub mod bits_eventfd;
 pub mod bits_iovec;
 #[path = "bits_locale-t/mod.rs"]
 pub mod bits_locale_t;
diff --git a/src/header/mod.rs.orig b/src/header/mod.rs.orig
new file mode 100644
index 0000000000..c078fbe1c8
--- /dev/null
+++ b/src/header/mod.rs.orig
@@ -0,0 +1,150 @@
+//! POSIX header implementations.
+
+pub mod _aio;
+pub mod _fenv;
+pub mod arpa_inet;
+pub mod assert;
+pub mod bits_arpainet;
+pub mod bits_eventfd;
+pub mod bits_iovec;
+#[path = "bits_locale-t/mod.rs"]
+pub mod bits_locale_t;
+pub mod bits_pthread;
+#[path = "bits_safamily-t/mod.rs"]
+pub mod bits_safamily_t;
+#[path = "bits_sigset-t/mod.rs"]
+pub mod bits_sigset_t;
+#[path = "bits_socklen-t/mod.rs"]
+pub mod bits_socklen_t;
+pub mod bits_timespec;
+// complex.h implemented in C
+pub mod cpio;
+pub mod crypt;
+pub mod ctype;
+// TODO: curses.h (deprecated)
+// TODO: devctl.h
+pub mod dirent;
+#[path = "dl-tls/mod.rs"]
+pub mod dl_tls;
+pub mod dlfcn;
+pub mod elf;
+pub mod endian;
+pub mod err;
+pub mod errno;
+pub mod fcntl;
+pub mod float;
+// TODO: fmtmsg.h
+pub mod fnmatch;
+// TODO: ftw.h
+pub mod getopt;
+pub mod glob;
+pub mod grp;
+// TODO: iconv.h
+pub mod ifaddrs;
+pub mod inttypes;
+// iso646.h implemented in C
+pub mod langinfo;
+// TODO: libintl.h
+pub mod libgen;
+pub mod limits;
+pub mod locale;
+pub mod malloc;
+// TODO unfinished, unguard feature when ready
+#[cfg(feature = "math_libm")]
+pub mod math;
+pub mod monetary;
+// TODO: mqueue.h
+// TODO: ndbm.h
+pub mod net_if;
+pub mod netdb;
+pub mod netinet_in;
+pub mod netinet_ip;
+pub mod netinet_tcp;
+// TODO: nl_types.h
+// TODO: Remove C header paths.h when cbindgen can export C/Rust strs
+// pub mod paths;
+pub mod poll;
+pub mod pthread;
+pub mod pty;
+pub mod pwd;
+// TODO: re_comp.h (deprecated)
+pub mod regex;
+// TODO: regexp.h (deprecated)
+pub mod sched;
+// TODO: search.h
+pub mod semaphore;
+pub mod setjmp;
+pub mod sgtty;
+pub mod shadow;
+pub mod signal;
+pub mod spawn;
+// TODO: stdalign.h (likely C implementation)
+// stdarg.h implemented in C
+// stdatomic.h implemented in C
+// stdbool.h implemented in C
+// stddef.h implemented in C
+// stdint.h implemented in C
+pub mod stdio;
+pub mod stdlib;
+// TODO: stdnoreturn.h (likely C implementation)
+pub mod string;
+pub mod strings;
+// TODO: stropts.h (deprecated)
+pub mod sys_auxv;
+pub mod sys_epoll;
+pub mod sys_eventfd;
+pub mod sys_file;
+pub mod sys_ioctl;
+// TODO: sys/ipc.h
+pub mod sys_mman;
+// TODO: sys/msg.h
+pub mod sys_ptrace;
+pub mod sys_resource;
+pub mod sys_select;
+// TODO: sys/sem.h
+// TODO: sys/shm.h
+pub mod sys_socket;
+pub mod sys_stat;
+pub mod sys_statvfs;
+#[allow(non_upper_case_globals)]
+pub mod sys_syscall;
+pub mod sys_time;
+#[deprecated]
+pub mod sys_timeb;
+//pub mod sys_times;
+pub mod arch_aarch64_user;
+pub mod arch_riscv64_user;
+pub mod arch_x64_user;
+pub mod sys_signalfd;
+#[cfg(not(target_arch = "x86"))] // TODO: x86
+pub mod sys_procfs;
+pub mod sys_random;
+pub mod sys_timerfd;
+pub mod sys_syslog;
+pub mod sys_types;
+#[allow(non_camel_case_types)]
+pub mod sys_types_internal;
+pub mod sys_uio;
+pub mod sys_un;
+pub mod sys_utsname;
+pub mod sys_wait;
+pub mod tar;
+// TODO: term.h (deprecated)
+pub mod termios;
+// TODO: tgmath.h (likely C implementation)
+// TODO: threads.h
+pub mod time;
+// TODO: uchar.h
+// TODO: ucontext.h (deprecated)
+// TODO: ulimit.h (deprecated)
+// TODO: unctrl.h (deprecated)
+pub mod unistd;
+#[deprecated]
+pub mod utime;
+pub mod utmp;
+// TODO: utmpx.h
+// TODO: varargs.h (deprecated)
+pub mod wchar;
+pub mod wctype;
+// TODO: wordexp.h
+// TODO: xti.h (deprecated)
diff --git a/src/header/sys_eventfd/cbindgen.toml b/src/header/sys_eventfd/cbindgen.toml
index ab821310eb..d6750cc523 100644
--- a/src/header/sys_eventfd/cbindgen.toml
+++ b/src/header/sys_eventfd/cbindgen.toml
@@ -1,12 +1,8 @@
-sys_includes = ["stdint.h", "stddef.h"]
-include_guard = "_SYS_EVENTFD_H"
-trailer = """
+sys_includes = ["stdint.h"]
+after_includes = """
 typedef uint64_t eventfd_t;
-
-int eventfd(unsigned int initval, int flags);
-int eventfd_read(int fd, eventfd_t *value);
-int eventfd_write(int fd, eventfd_t value);
 """
+include_guard = "_SYS_EVENTFD_H"
 language = "C"
 style = "Tag"
 no_includes = true
diff --git a/src/header/sys_eventfd/mod.rs b/src/header/sys_eventfd/mod.rs
index 04fa30eaa0..f9ad374a7f 100644
--- a/src/header/sys_eventfd/mod.rs
+++ b/src/header/sys_eventfd/mod.rs
@@ -1,7 +1,58 @@
-use crate::platform::types::{c_int, uint64_t};
+use alloc::format;
+use crate::c_str::{CStr, CString};
+use crate::error::{Errno, ResultExt};
+use crate::header::fcntl::{O_CLOEXEC, O_NONBLOCK, O_RDWR};
+use crate::header::errno::EFAULT;
+use crate::header::errno::EINVAL;
+use crate::platform::{Pal, Sys, types::{c_int, c_uint}};
 
-pub type eventfd_t = uint64_t;
+// Re-export eventfd_t from bits/eventfd.h
+pub use crate::header::bits_eventfd::eventfd_t;
 
 pub const EFD_SEMAPHORE: c_int = 1;
 pub const EFD_CLOEXEC: c_int = 0x80000;
 pub const EFD_NONBLOCK: c_int = 0x800;
+
+#[unsafe(no_mangle)]
+pub extern "C" fn eventfd(initval: c_uint, flags: c_int) -> c_int {
+    let supported = EFD_CLOEXEC | EFD_NONBLOCK | EFD_SEMAPHORE;
+    if flags & !supported != 0 {
+        return Err::<c_int, _>(Errno(EINVAL)).or_minus_one_errno();
+    }
+    let sem = if flags & EFD_SEMAPHORE != 0 { 1 } else { 0 };
+    let path = format!("/scheme/event/eventfd/{}/{}", initval, sem);
+    let cpath = match CString::new(path) {
+        Ok(p) => p,
+        Err(_) => return Err::<c_int, _>(Errno(EINVAL)).or_minus_one_errno(),
+    };
+
+    let mut oflag = O_RDWR;
+    if flags & EFD_CLOEXEC == EFD_CLOEXEC {
+        oflag |= O_CLOEXEC;
+    }
+    if flags & EFD_NONBLOCK == EFD_NONBLOCK {
+        oflag |= O_NONBLOCK;
+    }
+    Sys::open(CStr::borrow(&cpath), oflag, 0).or_minus_one_errno()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn eventfd_read(fd: c_int, value: *mut eventfd_t) -> c_int {
+    if value.is_null() {
+        return Err::<c_int, _>(Errno(EFAULT)).or_minus_one_errno();
+    }
+    let mut buf = [0u8; 8];
+    match Sys::read(fd, &mut buf) {
+        Ok(8) => { unsafe { *value = u64::from_ne_bytes(buf); } 0 }
+        _ => -1,
+    }
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn eventfd_write(fd: c_int, value: eventfd_t) -> c_int {
+    let buf = value.to_ne_bytes();
+    match Sys::write(fd, &buf) {
+        Ok(8) => 0,
+        _ => -1,
+    }
+}
diff --git a/src/header/sys_eventfd/mod.rs.orig b/src/header/sys_eventfd/mod.rs.orig
new file mode 100644
index 0000000000..04fa30eaa0
--- /dev/null
+++ b/src/header/sys_eventfd/mod.rs.orig
@@ -0,0 +1,7 @@
+use crate::platform::types::{c_int, uint64_t};
+
+pub type eventfd_t = uint64_t;
+
+pub const EFD_SEMAPHORE: c_int = 1;
+pub const EFD_CLOEXEC: c_int = 0x80000;
+pub const EFD_NONBLOCK: c_int = 0x800;