IMX8MM u-boot and kernel silent

[baptiste]

Hi,

I want to reduce my design boot time.
I follow the AN13709 guide, but no way.

I use yocto with an EVK Board (Imx8Nano_EVK board, but the processor is an IMX8Mini).

Could you help me to ?

1 - Silent u-boot 
Autoboot delay = -2 OK (in imx8mm_evk.k) 
But i don't want u-boot write to serial, how can i achieve this permanently with yocto ?

2 - Silent Kernel

How to set bootargs with quiet args (always with Yocto) and permanently (for mass production).

Best regards,
Baptiste

[baptiste]

Hi QMiller,

Thanks for your reply.

I don't find  but include/configs/imx8mm_evk.h
I have put this : 

#define CONFIG_BOOTDELAY -2

#define CONFIG_DISABLE_CONSOLE #define CONFIG_SILENT_CONSOLE #define CONFIG_SYS_DEVICE_NULLDEV

 I have put code in board_early_init_f(board/freescale/imx8mm_evk/imx8mm_evk.c), gd->flags |= (GD_FLG_SILENT | GD_FLG_DISABLE_CONSOLE

 The only thing that is working is that autoboot has no delay anymore (Hit key ...).

For my question to silent kernel permanently, do you know where to set bootargs ?

Best regards

[Zhiming_Liu]

You can set the console=null  in bootargs, the kernel log will not output.

[baptiste]

Hi Qmiller,

I will try, but where ?
In which file ?

Best regards

[Zhiming_Liu]

For your question one and two, you can import patch in yocto, like disable-uboot-serial.patch and queit-bootargs.patch, modify the u-boot-imx_2022.04.b refering this :https://stackoverflow.com/questions/45584131/how-patching-works-in-yocto

For disabling the serial in uboot, you can try below code: 

• Add the following defines to the board's config header(located in include/configs/imx8mm_board.h

    #define CONFIG_DISABLE_CONSOLE
    #define CONFIG_SILENT_CONSOLE
    #define CONFIG_SYS_DEVICE_NULLDEV
  

• Add below code in board_early_init_f(board/freescale/imx8mm_evk/imx8mm_evk.c), gd->flags |= (GD_FLG_SILENT | GD_FLG_DISABLE_CONSOLE