diff --git a/libc/include/sys/uio.h b/libc/include/sys/uio.h
index 37961e3..583cfc6 100644
--- a/libc/include/sys/uio.h
+++ b/libc/include/sys/uio.h
@@ -26,8 +26,12 @@
  * SUCH DAMAGE.
  */
 
-#ifndef _SYS_UIO_H_
-#define _SYS_UIO_H_
+#pragma once
+
+/**
+ * @file sys/uio.h
+ * @brief Multi-buffer ("vector") I/O operations using `struct iovec`.
+ */
 
 #include <sys/cdefs.h>
 #include <sys/types.h>
@@ -35,21 +39,124 @@
 
 __BEGIN_DECLS
 
+/**
+ * [readv(2)](http://man7.org/linux/man-pages/man2/readv.2.html) reads
+ * from an fd into the `__count` buffers described by `__iov`.
+ *
+ * Returns the number of bytes read on success,
+ * and returns -1 and sets `errno` on failure.
+ */
 ssize_t readv(int __fd, const struct iovec* __iov, int __count);
+
+/**
+ * [writev(2)](http://man7.org/linux/man-pages/man2/writev.2.html) writes
+ * to an fd from the `__count` buffers described by `__iov`.
+ *
+ * Returns the number of bytes written on success,
+ * and returns -1 and sets `errno` on failure.
+ */
 ssize_t writev(int __fd, const struct iovec* __iov, int __count);
 
 #if defined(__USE_GNU)
-ssize_t preadv(int __fd, const struct iovec* __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(preadv64) __INTRODUCED_IN(24);
-ssize_t pwritev(int __fd, const struct iovec* __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(pwritev64) __INTRODUCED_IN(24);
-ssize_t preadv64(int __fd, const struct iovec* __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
-ssize_t pwritev64(int __fd, const struct iovec* __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
-#endif
 
-#if defined(__USE_GNU)
+/**
+ * [preadv(2)](http://man7.org/linux/man-pages/man2/preadv.2.html) reads
+ * from an fd into the `__count` buffers described by `__iov`, starting at
+ * offset `__offset` into the file.
+ *
+ * Returns the number of bytes read on success,
+ * and returns -1 and sets `errno` on failure.
+ *
+ * Available since API level 24.
+ */
+ssize_t preadv(int __fd, const struct iovec* __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(preadv64) __INTRODUCED_IN(24);
+
+/**
+ * [pwritev(2)](http://man7.org/linux/man-pages/man2/pwritev.2.html) writes
+ * to an fd from the `__count` buffers described by `__iov`, starting at offset
+ * `__offset` into the file.
+ *
+ * Returns the number of bytes written on success,
+ * and returns -1 and sets `errno` on failure.
+ *
+ * Available since API level 24.
+ */
+ssize_t pwritev(int __fd, const struct iovec* __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(pwritev64) __INTRODUCED_IN(24);
+
+/**
+ * Like preadv() but with a 64-bit offset even in a 32-bit process.
+ *
+ * Available since API level 24.
+ */
+ssize_t preadv64(int __fd, const struct iovec* __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
+
+/**
+ * Like pwritev() but with a 64-bit offset even in a 32-bit process.
+ *
+ * Available since API level 24.
+ */
+ssize_t pwritev64(int __fd, const struct iovec* __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
+
+/**
+ * [preadv2(2)](http://man7.org/linux/man-pages/man2/preadv2.2.html) reads
+ * from an fd into the `__count` buffers described by `__iov`, starting at
+ * offset `__offset` into the file, with the given flags.
+ *
+ * Returns the number of bytes read on success,
+ * and returns -1 and sets `errno` on failure.
+ *
+ * Available since API level 33.
+ */
+ssize_t preadv2(int __fd, const struct iovec* __iov, int __count, off_t __offset, int __flags) __RENAME_IF_FILE_OFFSET64(preadv64v2) __INTRODUCED_IN(33);
+
+/**
+ * [pwritev2(2)](http://man7.org/linux/man-pages/man2/pwritev2.2.html) writes
+ * to an fd from the `__count` buffers described by `__iov`, starting at offset
+ * `__offset` into the file, with the given flags.
+ *
+ * Returns the number of bytes written on success,
+ * and returns -1 and sets `errno` on failure.
+ *
+ * Available since API level 33.
+ */
+ssize_t pwritev2(int __fd, const struct iovec* __iov, int __count, off_t __offset, int __flags) __RENAME_IF_FILE_OFFSET64(pwritev64v2) __INTRODUCED_IN(33);
+
+/**
+ * Like preadv2() but with a 64-bit offset even in a 32-bit process.
+ *
+ * Available since API level 33.
+ */
+ssize_t preadv64v2(int __fd, const struct iovec* __iov, int __count, off64_t __offset, int __flags) __INTRODUCED_IN(33);
+
+/**
+ * Like pwritev2() but with a 64-bit offset even in a 32-bit process.
+ *
+ * Available since API level 33.
+ */
+ssize_t pwritev64v2(int __fd, const struct iovec* __iov, int __count, off64_t __offset, int __flags) __INTRODUCED_IN(33);
+
+/**
+ * [process_vm_readv(2)](http://man7.org/linux/man-pages/man2/process_vm_readv.2.html)
+ * reads from the address space of another process.
+ *
+ * Returns the number of bytes read on success,
+ * and returns -1 and sets `errno` on failure.
+ *
+ * Available since API level 23.
+ */
 ssize_t process_vm_readv(pid_t __pid, const struct iovec* __local_iov, unsigned long __local_iov_count, const struct iovec* __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
+
+/**
+ * [process_vm_writev(2)](http://man7.org/linux/man-pages/man2/process_vm_writev.2.html)
+ * writes to the address space of another process.
+ *
+ * Returns the number of bytes read on success,
+ * and returns -1 and sets `errno` on failure.
+ *
+ * Available since API level 23.
+ */
 ssize_t process_vm_writev(pid_t __pid, const struct iovec* __local_iov, unsigned long __local_iov_count, const struct iovec* __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
+
 #endif
 
 __END_DECLS
-
-#endif