# 10.5.构建并安装定制内核

待保存了自定义配置文件的编辑内容，就可以按照以下步骤编译内核源代码：

**过程：构建内核**

1. 切换到此目录：

   ```sh
   # cd /usr/src
   ```
2. 通过指定自定义内核配置文件的名称来编译新内核：

   ```sh
   # make buildkernel KERNCONF=MYKERNEL
   ```
3. 安装与指定内核配置文件关联的新内核。此命令将新内核复制到 /boot/kernel/kernel 并将旧内核保存到 /boot/kernel.old/kernel：

   ```sh
   # make installkernel KERNCONF=MYKERNEL
   ```
4. 关闭系统并重启进入新内核。如果出现问题，请参考 [内核无法启动](https://docs.freebsd.org/en/books/handbook/kernelconfig/#kernelconfig-noboot)。

默认情况下，当编译自定义内核时，所有内核模块都会重新编译。要更快地更新内核或仅构建自定义模块，可以在开始构建内核之前编辑 /etc/make.conf。

例如，以下变量指定要构建的模块列表，而不是默认构建所有模块：

```ini
MODULES_OVERRIDE = linux acpi
```

或者，此变量列出要从构建过程中排除的模块：

```ini
WITHOUT_MODULES = linux acpi sound
```

`NO_MODULES` 完全跳过模块构建，仅构建内核：

```ini
NO_MODULES = yes
```

**Ports 框架**包含依赖内核接口的驱动程序和模块（如 [graphics/drm-kmod](https://cgit.freebsd.org/ports/tree/graphics/drm-kmod/)、[emulators/virtualbox-ose-kmod](https://cgit.freebsd.org/ports/tree/emulators/virtualbox-ose-kmod/)）。使用 `PORTS_MODULES` 变量，每次内核构建时也会重新构建这些 port 并同步内核接口，确保“内核模块与内核本身保持同步”。内核树和 ports 树应一起更新。例如：

```ini
PORTS_MODULES = drm-kmod virtualbox-ose-kmod
```

还可以使用其他变量。有关详细信息，请参阅 [make.conf(5)](https://man.freebsd.org/cgi/man.cgi?query=make.conf\&sektion=5\&format=html)。


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