> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man4/umass.4.md).

# umass.4

`umass` — USB 大容量存储设备驱动

## 名称

`umass`

## 概要

`device da device scbus device pass device usb device umass`

在 loader.conf(5) 中：`umass_load`

## 描述

`umass` 驱动为连接到 USB 接口的大容量存储设备提供支持。

若检测到相应硬件，该驱动会由 [devmatch(8)](/man/man8/devmatch.8.md) 自动加载。若要在引导时手动加载该驱动，请在 [loader(8)](/man/man8/loader.8.md) 提示符下使用 `umass_load` 命令，或将其加入 loader.conf(5)。

要在自定义内核中使用此驱动，内核中必须配置 [usb(4)](/man/man4/usb.4.md) 和 [uhci(4)](/man/man4/uhci.4.md)、[ohci(4)](/man/man4/ohci.4.md)、[ehci(4)](/man/man4/ehci.4.md) 或 [xhci(4)](/man/man4/xhci.4.md) 中的至少一个。此外，由于 `umass` 使用 SCSI 子系统且有时充当 SCSI 设备，因此内核中还需包含 [da(4)](/man/man4/da.4.md) 和 scbus(4)。

## 硬件

`umass` 驱动支持以下 USB 大容量存储设备：

* USB 闪存盘
* USB 硬盘驱动器
* USB 软盘驱动器

`umass` 驱动尽力避免驱动器问题，但并非所有问题都能自动处理，因此可能需要使用 quirks。有关驱动器的 quirks，请参见 [usb\_quirk(4)](/man/man4/usb_quirk.4.md) 的 *USB 大容量存储 quirks* 部分。usbconfig(8) 的 `add_dev_quirk_vplh` 和 `add_quirk` 命令可动态管理这些 quirks。quirks 也可通过可调参数指定，详见 [usb\_quirk(4)](/man/man4/usb_quirk.4.md)。

## 实例

重新扫描多插槽读卡器上的所有插槽，其中插槽映射到单个 SCSI ID 上的不同 LUN：

```sh
camcontrol rescan 0:0:0
camcontrol rescan 0:0:1
camcontrol rescan 0:0:2
camcontrol rescan 0:0:3
```

通常引导时仅启用第一个插槽。此示例假设读卡器是系统中第一个 SCSI 总线且具有 4 个插槽。

## 参见

[cfumass(4)](/man/man4/cfumass.4.md), [ehci(4)](/man/man4/ehci.4.md), [ohci(4)](/man/man4/ohci.4.md), [uhci(4)](/man/man4/uhci.4.md), [usb(4)](/man/man4/usb.4.md), [usb\_quirk(4)](/man/man4/usb_quirk.4.md), [xhci(4)](/man/man4/xhci.4.md), [camcontrol(8)](/man/man8/camcontrol.8.md), usbconfig(8)。

## 历史

`umass` 驱动出现于 FreeBSD 4.3。

## 作者

`umass` 驱动由 MAEKAWA Masahide <bishop@rr.iij4u.or.jp> 和 Nick Hibma <n_hibma@FreeBSD.org> 编写。

本手册页由 Nick Hibma <n_hibma@FreeBSD.org> 编写。


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://book.bsdcn.org/man/man4/umass.4.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.