diff --git a/library/std/src/os/mikros/mod.rs b/library/std/src/os/mikros/mod.rs
index ddbd21c2b23..07f8179b5e7 100644
--- a/library/std/src/os/mikros/mod.rs
+++ b/library/std/src/os/mikros/mod.rs
@@ -14,6 +14,57 @@
 #[stable(feature = "mikros", since = "1.80.0")]
 pub use errno::Errno;
 
+
+#[stable(feature = "mikros", since = "1.80.0")]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum FileCreationMode {
+    NoCreate,
+    Create,
+    ForceCreate,
+}
+
+#[stable(feature = "mikros", since = "1.80.0")]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum FileWriteMode {
+    Start,
+    Truncate,
+    Append
+}
+
+#[stable(feature = "mikros", since = "1.80.0")]
+#[derive(Copy, Clone, Debug)]
+pub enum FileOpenMode {
+    Read,
+    Write(FileWriteMode, FileCreationMode),
+    ReadWrite(FileWriteMode, FileCreationMode),
+}
+
+impl FileOpenMode {
+    #[stable(feature = "mikros", since = "1.80.0")]
+    pub fn readable(self) -> bool {
+        match self {
+            Self::Read | Self::ReadWrite(_, _) => true,
+            Self::Write(_, _) => false,
+        }
+    }
+
+    #[stable(feature = "mikros", since = "1.80.0")]
+    pub fn writable(self) -> bool {
+        match self {
+            Self::Write(_, _) | Self::ReadWrite(_, _) => true,
+            Self::Read => false,
+        }
+    }
+
+    #[stable(feature = "mikros", since = "1.80.0")]
+    pub fn get_writing_details(self) -> Option<(FileWriteMode, FileCreationMode)> {
+        match self {
+            Self::Write(wr_mode, cr_mode) | Self::ReadWrite(wr_mode, cr_mode) => Some((wr_mode, cr_mode)),
+            Self::Read => None,
+        }
+    }
+}
+
 /// A prelude for conveniently writing platform-specific code.
 ///
 /// Includes all extension traits, and some important type definitions.
diff --git a/library/std/src/sys/pal/mikros/fs.rs b/library/std/src/sys/pal/mikros/fs.rs
index d5eb9e4e3ac..bbba86e80de 100644
--- a/library/std/src/sys/pal/mikros/fs.rs
+++ b/library/std/src/sys/pal/mikros/fs.rs
@@ -6,7 +6,7 @@
 use crate::hash::{Hash, Hasher};
 use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut, SeekFrom};
 use crate::os::mikros::ipc::rpc;
-use crate::os::mikros::{Errno, syscalls};
+use crate::os::mikros::{Errno, syscalls, FileOpenMode, FileCreationMode, FileWriteMode};
 use crate::path::{Component, Path, PathBuf};
 use crate::sys::time::SystemTime;
 use crate::sys::unsupported;
@@ -149,7 +149,14 @@ pub struct DirEntry {
 }
 
 #[derive(Clone, Debug)]
-pub struct OpenOptions {}
+pub struct OpenOptions {
+    read: bool,
+    write: bool,
+    append: bool,
+    truncate: bool,
+    create: bool,
+    create_new: bool,
+}
 
 #[derive(Copy, Clone, Debug, Default)]
 pub struct FileTimes {}
@@ -313,19 +320,75 @@ pub fn file_type(&self) -> io::Result<FileType> {
     }
 }
 
+
 impl OpenOptions {
     pub fn new() -> OpenOptions {
-        OpenOptions {}
+        OpenOptions {
+            // generic
+            read: false,
+            write: false,
+            append: false,
+            truncate: false,
+            create: false,
+            create_new: false,
+        }
     }
 
-    pub fn read(&mut self, _read: bool) {}
-    pub fn write(&mut self, _write: bool) {}
-    pub fn append(&mut self, _append: bool) {}
-    pub fn truncate(&mut self, _truncate: bool) {}
-    pub fn create(&mut self, _create: bool) {}
-    pub fn create_new(&mut self, _create_new: bool) {}
+    pub fn read(&mut self, read: bool) {
+        self.read = read;
+    }
+    pub fn write(&mut self, write: bool) {
+        self.write = write;
+    }
+    pub fn append(&mut self, append: bool) {
+        self.append = append;
+    }
+    pub fn truncate(&mut self, truncate: bool) {
+        self.truncate = truncate;
+    }
+    pub fn create(&mut self, create: bool) {
+        self.create = create;
+    }
+    pub fn create_new(&mut self, create_new: bool) {
+        self.create_new = create_new;
+    }
+
+
+    fn get_open_mode(&self) -> io::Result<FileOpenMode> {
+        if !self.write && (self.append || self.truncate || self.create || self.create_new) {
+            return Err(Errno::EINVAL.into());
+        }
+        if self.append && self.truncate {
+            return Err(Errno::EINVAL.into());
+        }
+        if self.append && self.truncate {
+            return Err(Errno::EINVAL.into());
+        }
+        if !self.read && !self.write {
+            return Err(Errno::EINVAL.into());
+        }
+        if self.read && !self.write {
+            return Ok(FileOpenMode::Read);
+        }
+        let cr_mode = match (self.create, self.create_new) {
+            (false, false) => FileCreationMode::NoCreate,
+            (true, false) => FileCreationMode::Create,
+            (_, true) => FileCreationMode::ForceCreate,
+        };
+        let wr_mode = match (self.append, self.truncate) {
+            (false, false) => FileWriteMode::Start,
+            (false, true) => FileWriteMode::Truncate,
+            (true, false) => FileWriteMode::Append,
+            (true, true) => unreachable!()
+        };
+        match self.read {
+            false => Ok(FileOpenMode::Write(wr_mode, cr_mode)),
+            true => Ok(FileOpenMode::ReadWrite(wr_mode, cr_mode)),
+        }
+    }
 }
 
+
 impl File {
     pub fn open(path: &Path, _opts: &OpenOptions) -> io::Result<File> {
         let path = path.canonicalize()?;