====== Kernel Bootargs User Config ======

===== Introduction =====

This page mainly introduces how-to user can customize linux kernel bootargs under Ubuntu.

===== How-to Customize Linux Kernel Bootargs =====

You can edit file ''/boot/uEnv.txt'' to add the user bootargs.

The default file contents are similar as below:

```shell
$ cat /boot/uEnv.txt 
#############################DO NOT TOUCH THIS OPTION#############################
rootdev=root=UUID=a92f7f2f-0d4a-4607-a45a-4549cfe71036
partitiontype=partition_type=generic
#############################DO NOT TOUCH THIS OPTION#############################
## Setup console
consoles=console=ttyS0,921600 console=tty0

## Setup FAN mode
fan_mode=auto

## Add user args here, spilt with space.
## e.g. Add bootargs 'test1=111 test2=222'
## boot_user_args=test1=111 test2=222
boot_user_args=
```

==== Normal Bootargs ====
You can append your bootargs to the configuration ''boot_user_args=''.

e.g. Add bootargs ''cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory systemd.unified_cgroup_hierarchy=0'', the variable ''boot_user_args='' should be as below:

```shell
boot_user_args=cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory systemd.unified_cgroup_hierarchy=0
```

==== Console Bootargs ====
<WRAP important>
This configuration is suitable for only the 5.15 kernel.
</WRAP>

You can change the linux UART pins for normal usage by modifying the configuration ''console=''

^ UART mode ^ Configuration ^
| Configure the UART for linux debug | ''consoles=console=ttyS0,<baud rate> console=tty0'' |
| Configure the UART for general usage | ''consoles=console=tty0'' |

eg. Enable linux UART console with 921600 baud rate should be as below:

```shell
consoles=console=ttyS0,921600 console=tty0
```

^ Model          ^ Baudrate   ^
| VIM3/VIM3L     | 115200     |
| VIM4/VIM1S     | 921600     |

<WRAP important >
Please make sure the bootargs are split with space and don't add quotation marks.
</WRAP>


<WRAP info >
Save the file and reboot to take effect.
</WRAP>

===== How-to Check Linux Kernel Bootargs =====

After reboot system, we can check current linux kernel bootargs

```shell
$ cat /proc/cmdline
```