> 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/man9/device.9.md).

# device.9

`device` — 设备的抽象表示

## 名称

`device`

## 概要

```c
typedef struct _device *device_t;
```

## 描述

设备对象表示连接到系统的一件硬件，例如扩展卡、该卡所插入的总线、连接到该扩展卡的磁盘驱动器等。系统定义了一个设备 `root_bus`，所有其他设备都在自动配置期间动态创建。通常，代表系统中顶级总线（ISA、PCI 等）的设备将直接附加到 `root_bus`，而其他设备将作为其相关总线的子设备添加。

系统中的设备形成一棵树。除 `root_bus` 外的所有设备都有父设备（参见 [device\_get\_parent(9)](/man/man9/device_get_parent.9.md)）。此外，任何设备都可以有附加到其上的子设备（参见 [device\_add\_child(9)](/man/man9/device_add_child.9.md)、device\_add\_child\_ordered(9)、[device\_find\_child(9)](/man/man9/device_find_child.9.md)、[device\_get\_children(9)](/man/man9/device_get_children.9.md) 和 [device\_delete\_child(9)](/man/man9/device_delete_child.9.md)）。

已成功探测并附加到系统的设备还将有一个驱动程序（参见 [device\_get\_driver(9)](/man/man9/device_get_driver.9.md) 和 [driver(9)](/man/man9/driver.9.md)）和一个 devclass（参见 [device\_get\_devclass(9)](/man/man9/device_get_devclass.9.md) 和 [devclass(9)](/man/man9/devclass.9.md)）。设备的其他各种属性包括单元号（参见 [device\_get\_unit(9)](/man/man9/device_get_unit.9.md)）、详细描述（通常由驱动程序提供，参见 [device\_set\_desc(9)](/man/man9/device_set_desc.9.md) 和 device\_get\_desc(9)）、一组总线特定的变量（参见 [device\_get\_ivars(9)](/man/man9/device_get_ivars.9.md)）以及一组驱动程序特定的变量（参见 [device\_get\_softc(9)](/man/man9/device_get_softc.9.md)）。

设备可以处于以下几种状态之一：

**`DS_NOTPRESENT`** 设备尚未探测存在性或探测失败

**`DS_ALIVE`** 设备探测成功但尚未附加

**`DS_ATTACHED`** 设备已成功附加

**`DS_BUSY`** 设备当前已打开

可以通过调用 [device\_get\_state(9)](/man/man9/device_get_state.9.md) 来确定设备的当前状态。

## 参见

[devclass(9)](/man/man9/devclass.9.md), [driver(9)](/man/man9/driver.9.md)

## 作者

本手册页由 Doug Rabson 编写。


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