如何加载设备树覆盖

Question

我知道这是一个话题，还有其他几篇文章。但是一个都没有？其中有一个被接受的答案，甚至一个有用的评论。但简而言之，如何加载设备树模块(而不重新编译内核)？

到目前为止，我可以找到以下方法：

1. 在运行时加载，每个cat enI2C4.dtbo>/sys/kernel/config/device-tree/overlays。
2. 在引导过程中加载，在/boot/bootenv.txt和/或/boot/uEnv.txt中指定D6文件。在这两种情况下，内容都是(enI2C4.dtbo存储在/boot下)：

overlays=enI2C4.dtbo

遗憾的是，他们中没有一个人为我工作：

1. device-tree目录不存在，mkdir返回Operation not permitted。这个问题的大多数解决方案似乎都是编译自己的内核，我认为这并不是真正必要的，也不是我想要做的事情。
2. 编辑/创建这两个文件之一似乎没有任何效果。我既不能在find /proc/device-tree/ -type f -exec head {} + | grep I2C中找到我的覆盖，dmesg也不返回任何特殊的内容。

我在这里错过了什么？是否有第三种选择，或者(可能是愚蠢的)东西，我在这里错过了？

作为背景和其他信息：

我试图通过以下方式在I2C4上启用i.MX 8M +：

$ lsb_release -a
Distributor ID: ampliPHY
Description:    ampliPHY GNU/Linux BSP-Yocto-NXP-i.MX8MP-PD22.1.0 (hardknott)
Release:        BSP-Yocto-NXP-i.MX8MP-PD22.1.0
Codename:       hardknott

.dts文件是：

/dts-v1/;

#include "imx8mp.dtsi" 

&i2c4 {
    clock-frequency = <400000>;
    pinctrl-names = "default", "gpio";
    status = "okay";
};

这里是/boot/bootenv.txt和/boot/uEnv.txt文件都就位的引导程序(在挂载/引导/之后)。

[  OK  ] Mounted /boot.
[  OK  ] Reached target Local File Systems.
         Starting Create Volatile Files and Directories...
[  OK  ] Finished Create Volatile Files and Directories.
         Starting Network Name Resolution...
         Starting Network Time Synchronization...
[  OK  ] Started Network Name Resolution.
[  OK  ] Started Network Time Synchronization.
[  OK  ] Reached target Network.
[  OK  ] Reached target Host and Network Name Lookups.
[  OK  ] Reached target System Initialization.
[    6.550051] imx-sdma 30bd0000.dma-controller: sdma firmware not ready!
[    6.557338] imx-sdma 30bd0000.dma-controller: sdma firmware not ready!
[    6.564225] imx-sdma 30bd0000.dma-controller: sdma firmware not ready!
[    6.570968] imx-sdma 30bd0000.dma-controller: sdma firmware not ready!
[    6.577572] imx-sdma 30bd0000.dma-controller: sdma firmware not ready!
[    6.597437] imx-cdnhdmi sound-hdmi: snd_soc_register_card failed (-517)
[  OK  ] Started     6.605376] fsl-aud2htx 30cb0000.aud2htx: Unbalanced pm_runtime_enable!
;39mDaily Cleanup of Temporary Di[    6.613814] fsl-aud2htx 30cb0000.aud2htx: failed to init imx pcm dma: -517
rectories.
[  OK  ] Reached target System Time Set.
[  OK  ] Reached target System Time Synchronized.
[  OK  ] Reached target Timers.
[  OK  ] Listening on D-Bus System Message Bus Socket.
[  OK  ] Listening on PC/SC Smart Card Daemon Activation Socket.
         Starting sshd.socket.
[  OK  ] Started NFS status monitor for NFSv2/3 locking..
[  OK  ] Listening on sshd.socket.
[  OK  ] Reached target Sockets.
[  OK  ] Reached target Basic System.
         Starting Save/Restore Sound Card State...
[  OK  ] Started D-Bus System Message Bus.
[  OK  ] Started Start fan control, if configured.
[  OK  ] Started Linux Firmware Loader Daemon.
         Starting User Login Management...
         Starting Permit User Sessions...
[    6.927296] imx-sdma 30bd0000.dma-controller: firmware found.
         Starting OpenSS[    6.934041] imx-sdma 30bd0000.dma-controller: loaded firmware 4.6
H Key Generation...
[  OK  ] Finished Save/Restore Sound Card State.
[  OK  ] Finished Permit User Sessions.
[  OK  ] Finished OpenSSH Key Generation.
[  OK  ] Reached target Sound Card.
[  OK  ] Started Getty on tty1.
[  OK  ] Started Serial Getty on ttymxc0.
[  OK  ] Reached target Login Prompts.
[  OK  ] Started User Login Management.
[  OK  ] Reached target Multi-User System.
[    7.198435] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready
[    7.204785] IPv6: ADDRCONF(NETDEV_CHANGE): can1: link becomes ready

 ____   _   _ __   __ _____  _____   ____
|  _ \ | | | |\ \ / /|_   _|| ____| / ___|
| |_) || |_| | \ V /   | |  |  _|  | |
|  __/ |  _  |  | |    | |  | |___ | |___
|_|    |_| |_|  |_|    |_|  |_____| \____|

    _     __  __  ____   _      ___  ____   _   _ __   __
   / \   |  \/  ||  _ \ | |    |_ _||  _ \ | | | |\ \ / /
  / _ \  | |\/| || |_) || |     | | | |_) || |_| | \ V /
 / ___ \ | |  | ||  __/ | |___  | | |  __/ |  _  |  | |
/_/   \_\|_|  |_||_|    |_____||___||_|    |_| |_|  |_|

Answer 1

对于/sys/kernel/config/device-tree/overlays/，您应该有一个使用CONFIG_OF_CONFIGFS=y构建的内核(这不是一个上游特性，但在一些内核中可用)。