I am building a Yocto image for Intel Edison.
One of the image’s components is u-boot with an Edison-specific patch. By default, Edison’s UART port is used for u-boot console. I want to disable this feature, but only on the serial interface(u-boot also listens on USB and that needs to stay).
My main concern is the “Press any key to stop autoboot” feature on the UART port. I need this port to connect an accessory that might send something during the boot process of the main device.
How do I approach this problem? Is there an environment variable for this, or do I need to modify the sources?
Thanks in advance!
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Answer
I’m getting back to this issue almost a year later, now I’ve managed to find a proper solution.
The board I was working on had a reasonably new u-boot in its BSP. To disable the serial console I had to do the following:
Add the following defines to the board’s config header(located in include/configs/board.h):
#define CONFIG_DISABLE_CONSOLE #define CONFIG_SILENT_CONSOLE #define CONFIG_SYS_DEVICE_NULLDEV
Check if your board has early_init_f enabled in the same file:
#define CONFIG_BOARD_EARLY_INIT_F 1
Find the arch file(Something like arch/x86/cpu/architecture/architecture.c) and add this call to its early_init_f function. It actually modifies board’s global data variable to have these flags:
gd->flags |= (GD_FLG_SILENT | GD_FLG_DISABLE_CONSOLE);
My board did not have one, so I had to add the whole function
int board_early_init_f(void) { gd->flags |= (GD_FLG_SILENT | GD_FLG_DISABLE_CONSOLE); return 0; }
Example: If you are looking for board_early_init_f of Orange Pi 4B it is in /build/cache/sources/u-boot/v2020.10/board/rockchip/evb_rk3399/evb-rk3399.c
That’s it. Hope this helps someone else!
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