Problem with console without console=ttyS0 bootarg

[Rafał Miłecki]

On 21.05.2017 22:22, Rafał Miłecki wrote:
> On 14 March 2017 at 07:37, Rafał Miłecki <zajec5 at gmail.com> wrote:
>> My current DTS file contains following entry:
>> bootargs = "console=ttyS0,115200"
>> and it works in a following way:
>>
>> Press the [f] key and hit [enter] to enter failsafe mode
>> Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
>> [    9.320212] procd: - early -
>> [    9.323174] procd: - watchdog -
>> [    9.924724] procd: - ubus -
>> [    9.986055] procd: - init -
>> Please press Enter to activate this console.
>> === WARNING! =====================================
>> There is no root password defined on this device!
>> Use the "passwd" command to set up a new password
>> in order to prevent unauthorized SSH logins.
>> --------------------------------------------------
>> root at LEDE:/#
>>
>>
>>
>> If I enable "ttylogin" in /etc/config/system it works quite similarly (just
>> asks for a login):
>>
>> Press the [f] key and hit [enter] to enter failsafe mode
>> Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
>> [    9.362481] procd: - early -
>> [    9.365550] procd: - watchdog -
>> [    9.983522] procd: - ubus -
>> [   10.044877] procd: - init -
>> Please press Enter to activate this console.
>> LEDE login:
>> LEDE login: root
>> === WARNING! =====================================
>> There is no root password defined on this device!
>> Use the "passwd" command to set up a new password
>> in order to prevent unauthorized SSH logins.
>> --------------------------------------------------
>> root at LEDE:~#
>>
>>
>> My problem appears when I drop bootargs and use:
>> stdout-path = "/chipcommonA/serial at 0300:115200";
>> instead (which is a non-deprecated DTS solution).
>> In such case I can't login anymore:
>>
>> Press the [f] key and hit [enter] to enter failsafe mode
>> Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
>> [    9.340180] procd: - early -
>> [    9.343141] procd: - watchdog -
>> [    9.944758] procd: - ubus -
>> [   10.006092] procd: - init -
>>
>>
>> Do you know what's the reason for this? Can we have a proper console support
>> while using upstream preferred syntax for the stdout-path?
>> Please note entering failsafe mode it not affected by this.
> 
> Since noone got idea how to handle this, I added workaround as for now
> in commit 0a05fbd135663 ("bcm53xx: add support for TP-LINK Archer C5
> V2")
> https://git.lede-project.org/?p=source.git;a=commit;h=0a05fbd1356631a1f903adcd63ffb05550537667
> 
> You can find it in the 320-ARM-dts-BCM5301X-Add-serial-to-the-bootargs.patch

I hit this problem again while working on the bcm4908 target. This time I
debugged it. It's caused by the procd's askconsole(). That function requires
console device (e.g. ttyS0) to be specified in cmdline's console.

I don't know how to fix it. Reading "stdout-path" from "chosen" will return
"serial0:115200n8". Then it's possible to read "serial0" alias which points
to some DT node (e.g. /bus at ff800000/serial at 640).

The problem I have is that my /bus at ff800000/serial at 640 doesn't reference
/dev/ttyS0 anyhow.