Unibone serial port settings

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roelof...@yahoo.com

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May 5, 2022, 4:47:19 AMMay 5
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A little question,

Where do I change the serial BBB port settings like speed and start/stop bits?
Thanks in advance!

Regards, Roland

Joerg Hoppe

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May 5, 2022, 4:55:26 AMMay 5
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Am 05.05.2022 um 10:47 schrieb 'roelof...@yahoo.com' via UniBone:
> A little question,
>
> Where do I change the serial BBB port settings like speed and
> start/stop bits?

Which use: for serial login to root?

Jörg

roelof...@yahoo.com

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May 5, 2022, 5:05:59 AMMay 5
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Which use: for serial login to root?

Hi Joerg,

Yes, to access Linux trough the serial port.

Regards, Roland
 

Joerg Hoppe

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May 6, 2022, 2:01:22 AMMay 6
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Hi,

This was quite some home work!
I had to re-explored Debians "systemd" logic ... wish back the days of "System V init".

From my old notes and current understanding:

- For each serial port enabled for login, there must exist an special entry for the UART in
    /etc/systemd/system/getty.target.wants
It is normally a link to the generic
    /lib/systemd/system/getty@.service

It is generated with
    ln -sf /lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/ge...@ttyS1.service

To enable UART2 it would be     
        ln -sf /lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/ge...@ttyS2.service

    
The key command in this rule-file is
    ExecStart=-/sbin/agetty -a root --noclear %I $TERM
See man page of "agetty" for options, the baud rate goes there.
For example the"-a root" comamndline option does the "auto login".

It may be wise not to link but to copy "getty@.service" to  "ge...@ttyS1.service",
and operate on the copy only.

    cp -sf /lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/ge...@ttyS1.service


Joerg
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