Stop U-Boot from Booting Linux Kernel

Discussion about U-Boot and the kernel.

Stop U-Boot from Booting Linux Kernel

Postby Nobody93 » Tue May 04, 2021 9:02 am

Hello,

I have the following problem:

I added a modprobe setting to the kernel (detecting an PWM Interface).
This will unfortunately freeze the kernel.


Question: Is there a way to stop the U-Boot from booting the linux kernel.

I have an Odroid C1+ with the actual arch linux and uboot (default setting) running.
In addition I could connect the serial terminal .... -> would this be helpful?

NOTE: After booting, I see that the kernel initalisiation is running for about 2 seconds (probing everything else) -> until it comes to the PWM modprobe...

NOTE2: The Odroid C1+ is installed in a setup where it is very hard to disassemble. So I could not remove the SD-Card and modify the setup at another computer ....
Nobody93
 
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Re: Stop U-Boot from Booting Linux Kernel

Postby Nobody93 » Wed May 05, 2021 6:47 pm

So, I solved the issue by myself.

If you are fast enough, you can stop U-Boot from booting Linux.
But you have to be really fast !?

NOTE: And the modprobe, what killed the kernel, I could disable it with:
Code: Select all
modprobe.blacklist=pwm-meson,pwm_ctrl

as an kernel option.
Nobody93
 
Posts: 5
Joined: Mon May 03, 2021 6:47 am

Re: Stop U-Boot from Booting Linux Kernel

Postby abobap » Fri May 07, 2021 7:16 am

>But you have to be really fast !?

Depends on the bootdelay u-boot env variable.

With bootdelay set to 0 the U-Boot countdown is disabled
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