kernel 4.1.2-bone 12, how to edit default cmdline

[Jan Kinkazu]

Hi all.

System starts with 

0.000000] Kernel command line: console=ttyO0,115200n8 root=UUID=250d80ed-1acd-4cc5-906f-2af2805ff23d ro rootfstype=ext4 rootwait fixrtc

even if there is nothing defined in uEnv.txt

Where and how i can edit default cmdline?

Thanks

[g...@novadsp.com]

> System starts with
> 0.000000] Kernel command line: console=ttyO0,115200n8 root=UUID=250d80ed-1acd-4cc5-906f-2af2805ff23d ro rootfstype=ext4 rootwait fixrtc
> even if there is nothing defined in uEnv.txt

Permanently or just once in a while?

See u-boot.cfg in u-boot repo for the default configuration otherwise explore the u-boot console.

[Robert Nelson]

The 'cmdline' variable in /boot/uEnv.txt

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[Artur Festyn]

Yes, cmdline is in uEnv.txt, but even when it's empty/hashed, kernel still gets Kernel command line: console=ttyO0,115200n8 root=UUID=250d80ed-1acd-4cc5-906f-2af2805ff23d ro rootfstype=ext4 rootwait fixrtc,

I assume it is in uboot.cfg?, thanks you both

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[Artur Festyn]

Hmm, I can't find uboot.cfg in bb-kernel folder, where else can I look?

[Robert Nelson]

On Thu, Jul 16, 2015 at 10:28 AM, 'Artur Festyn' via BeagleBoard
<beagl...@googlegroups.com> wrote:
> Hmm, I can't find uboot.cfg in bb-kernel folder, where else can I look?
>
> 2015-07-15 8:32 GMT+01:00 Artur Festyn <fes...@googlemail.com>:
>>
>> Yes, cmdline is in uEnv.txt, but even when it's empty/hashed, kernel still
>> gets Kernel command line: console=ttyO0,115200n8
>> root=UUID=250d80ed-1acd-4cc5-906f-2af2805ff23d ro rootfstype=ext4 rootwait
>> fixrtc,
>> I assume it is in uboot.cfg?, thanks you both

NO, your assumption about uboot.cfg is incorrect:

/boot/uEnv.txt

Regards,

--
Robert Nelson
https://rcn-ee.com/

[Artur Festyn]

Ok, probably it is not needed anymore. What is defined in uEnv.txt is just added to the end of kernel comand (cmdline=console=ttyS0,115200n8).

Doesn't look as pretty as it could look, but works.

[    0.000000] Kernel command line: console=ttyO0,115200n8 root=UUID=f0fe05d6-8783-46b7-8e05-4cccb006b84c ro rootfstype=ext4 rootwait fixrtc console=ttyS0,115200n8

[    3.066245] console [ttyS0] disabled

[    3.846121] console [ttyS0] enabled

[Robert Nelson]

On Thu, Jul 16, 2015 at 10:45 AM, 'Artur Festyn' via BeagleBoard
<beagl...@googlegroups.com> wrote:
> Ok, probably it is not needed anymore. What is defined in uEnv.txt is just
> added to the end of kernel comand (cmdline=console=ttyS0,115200n8).
> Doesn't look as pretty as it could look, but works.
> [ 0.000000] Kernel command line: console=ttyO0,115200n8
> root=UUID=f0fe05d6-8783-46b7-8e05-4cccb006b84c ro rootfstype=ext4 rootwait
> fixrtc console=ttyS0,115200n8
> [ 3.066245] console [ttyS0] disabled
> [ 3.846121] console [ttyS0] enabled

Humm, the kernel will rename ttyO0 -> ttyS0 automaticly... no reason
to add console twice..

[Artur Festyn]

:) Yes Robert, but:

1. I didn't like to see an error

2. I wanted to test console on different tty

3. W wanted to find out how to disable console on ttyS0.

I plan to use debug header as RS232 port for one of devices I am connecting to BBB.

Thank you anyway, Robert

It is pleasure to work with BBB, thanks to work you do with kernels, patches, dtbs'es, images and etc etc

[Robert Nelson]

On Thu, Jul 16, 2015 at 11:07 AM, 'Artur Festyn' via BeagleBoard
<beagl...@googlegroups.com> wrote:
> :) Yes Robert, but:
> 1. I didn't like to see an error
> 2. I wanted to test console on different tty
> 3. W wanted to find out how to disable console on ttyS0.
>
> I plan to use debug header as RS232 port for one of devices I am connecting
> to BBB.

add this to /boot/uEnv.txt:

console=ttyO0,115200n8

(and set it to anything you want and it'll override the default value
set in u-boot)

[Robert Nelson]

in u-boot it's added to the cmdline via:

console=${console}

[Artur Festyn]

Thank you very much.