> 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/imx6_snvs.4.md).

# imx6\_snvs.4

`imx6_snvs` — NXP i.MX6 片上实时时钟驱动

## 名称

`imx6_snvs`

## 概要

要将此驱动编译进内核，请在内核配置文件中加入以下行：

> device imx6\_snvs

或者，要在引导时以模块形式加载该驱动，请在 loader.conf(5) 中加入以下行：

```sh
imx6_snvs_load="YES"
```

## 描述

`imx6_snvs` 驱动为 i.MX6 片上实时时钟提供支持。它提供当日时间，分辨率约为 30 微秒。

“SNVS”代表 Secure Non-Volatile Storage（安全非易失性存储），指的是芯片内的一个子系统，在系统其余部分断电时（可选地）由电池供电。片上实时时钟是该子系统的一部分。SNVS 子系统的其他功能涉及安全、防篡改监测和电源控制；`imx6_snvs` 驱动目前不支持这些功能。

由于功耗相对较高，许多 i.MX6 系统不使用电池为 SNVS 供电。在此类系统中，此驱动能够在重启后提供非常精确的时间，但断电循环后则完全无法提供时间。如果系统提供了一个分辨率较低的 i2c 或其他类型的备用实时时钟，则同时配置两个时钟驱动是有意义的。这样可以让 SNVS 在重启后提供精确时间，而外部时钟在断电循环后提供近似时间。

## 历史

`imx6_snvs` 驱动首次出现于 FreeBSD 12.0。


---

# 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/imx6_snvs.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.