---
name: "rtsx"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/rtsx"
---

# rtsx(4)

Realtek SD card reader

## NAME

**rtsx** – Realtek SD card reader

## SYNOPSIS

**rtsx\* at pci?** **sdmmc\* at rtsx?**

## DESCRIPTION

The **rtsx** driver provides support for the Realtek RTS5209, RTS5227, RTS5229, RTS522A, RTS5249, RTS525A, RTL8402, RTL8411, and RTL8411B SD card readers.

The [sdmmc(4)](/sdmmc/4.md) subsystem performs SD/MMC transactions to communicate with SD or SDHC devices inserted into the SD slot.

## SEE ALSO

[intro(4)](/intro/4.md), [sdmmc(4)](/sdmmc/4.md)

## HISTORY

The **rtsx** driver first appeared in OpenBSD 5.3.

## AUTHORS

The **rtsx** driver was written by Stefan Sperling ⟨*stsp@openbsd.org*⟩.

## BUGS

The **rtsx** driver does not support MS (Memory Stick) and xD (Extreme Digital) devices even though the hardware supports them.

Support for SDIO interrupts is not implemented.