---
name: "mmc"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/mmc/4"
---

# mmc(4)

MultiMediaCard and SD Card bus driver

## NAME

**mmc** – MultiMediaCard and SD Card bus driver

## SYNOPSIS

**device** **mmc**

## DESCRIPTION

The **mmc** driver implements the MMC and SD Card bus. The **mmc** driver supports all MMC and SD bridges in the system. All SD or MMC cards in the system attach to an instance of **mmc**. The **mmc** bus typically has only one slot, and only memory cards. MultiMediaCards exist only in memory. SD Cards exist as memory, I/O, or combination cards.

## SEE ALSO

[mmcsd(4)](/mmcsd/4.md), [sdhci(4)](/sdhci/4.md) *SD Specifications, Part 1, Physical Layer, Simplified Specification*. *The MultiMediaCard System Specification*.

## BUGS

SDIO cards currently do not work.