[yocto] Changing the tty/UART of busybox

[Maxin B. John]

Hi Jakob,

>On Wed, Feb 28, 2018 at 11:15:42AM +0100, Jakob Hasse wrote:
>
>Hello,
>
>we need to change the tty on which busybox is sitting. Right now I could change
> the UART for the kernel and all program output after the boot to our favorite 
> UART (via kernel cmd line). But the login promt and all interaction with the 
> device is still on the old UART. So I guess it's a busybox configuration issue.
> Furthermore, when I try tty after login, it gives me: /dev/ttymxc4 (we want to use ttymx1).
>
>I looked here https://busybox.net/downloads/BusyBox.html and in menuconfig
> for an option to change the UART interface but couldn't find any. Furthermore I added
>
>::respawn:/sbin/getty -L ttymxc1 115200 vt100
>
>and this
>
>ttymxc1::respawn:/sbin/getty -L ttymxc1 115200 vt100
>
>to inittab to change the UART with no luck.
>Could someone here point me to documentation or give me a hint to achive this?

Generally, the console setting comes from our <machine>.conf. eg:
for beaglebone:
./meta-yocto-bsp/conf/machine/beaglebone-yocto.conf:
SERIAL_CONSOLE = "115200 ttyO0"

This gets processed in bitbake.conf:
SERIAL_CONSOLES ??= "${@d.getVar('SERIAL_CONSOLE').replace(' ', ';')}"

later, based on the init manager:
busybox, systemd-serialgetty, or sysvinit-inittab use it.

In this case, updating the "<machine>.conf" should help.

>Thanks in advance, all the Best,
>Jakob
>
>-- 
>Jakob Hasse
>Software Developement
>
>E: jakob.hasse at smart-home-technology.ch
>T: +41 44 552 02 66 
>
>Smart Home Technology GmbH
>www.smart-home-technology.ch

Best Regards,
Maxin