boot messages after login: prompt

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boot messages after login: prompt

Postby Milliways » Mon Oct 15, 2018 5:05 am

I have installed (and upgraded) Arch on my Raspberry Pi3.

On boot the system prompts for login: but continues to post boot messages. When these stop I login, but find it somewhat disturbing. Other distos display a login prompt AFTER boot has completed.

Is it possible to modify this behaviour?

On a possibly related issue the screen displays audit: messages. These are incomprehensible (at least to me) and annoying when trying to do something.
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Re: boot messages after login: prompt

Postby TheSaint » Mon Oct 15, 2018 5:26 am

I think you should address the kernel message to another TTY.
Post you /proc/cmdline.
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Re: boot messages after login: prompt

Postby Milliways » Mon Oct 15, 2018 8:03 am

$this->bbcode_second_pass_code('', '8250.nr_uarts=1 bcm2708_fb.fbwidth=1280 bcm2708_fb.fbheight=1024 bcm2708_fb.fbswap=1 vc_mem.mem_base=0x3ec00000 vc_mem.mem_size=0x40000000 root=/dev/mmcblk0p2 rw rootwait console=tty1 selinux=0 plymouth.enable=0 smsc95xx.turbo_mode=N dwc_otg.lpm_enable=0 elevator=noop
')
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Re: boot messages after login: prompt

Postby graysky » Mon Oct 15, 2018 10:47 am

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Re: boot messages after login: prompt

Postby TheSaint » Mon Oct 15, 2018 11:16 am

So you might try to redirect the dmesg to another TTY $this->bbcode_second_pass_code('', 'console=tty2 quiet audit=0')
To do it, I presume you have to edit /boot/boot.txt and run the ./mkscr after modification.

This will stop nagging messages over the UART1, but if you login via SSH wired or wireless, the dmesg won't appear.
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Re: boot messages after login: prompt

Postby Milliways » Wed Oct 17, 2018 12:02 am

Adding audit=0 to the command line works.

I still wonder WHY the login prompt appears in the middle of the kernel messages unlike other distos I use.

I DO NOT want to hide messages - just not have to look through a list to see if there is a prompt.
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Re: boot messages after login: prompt

Postby TheSaint » Wed Oct 17, 2018 4:41 am

Perhaps there's a little problem how the console is laid out.
For example if I start a ncurses session the window size is reduce to 25. Some time happen even for another reason. Mostly is the tty interface that will cause that.
For example I use konsole with picocom, the it happen at the bottom when the line is very long. If I use SSH login it is not happening.
For your case, you might opt to login from a SSH so the messages will go somewhere else. Then to see them it will take a dmesg ;)
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Re: boot messages after login: prompt

Postby summers » Wed Oct 17, 2018 9:46 am

Probably much of the reason you get messages after the login prompt, is that arch uses systemd to start up the system. This means it starts up init processing in parallel, but taking care of dependencies between different processes.

E.g. a login process only makes sense when the home file system is mounted.

Now when all dependencies for the the login are met, systemd will start the login process (actaully start up getty), and you can log in. However not everything will be up by then. e.g. the ethernet may not have yet come up, however this doesn't stop you logging in. but when the ethernet comes up the console will get a message.

Now this brings in the console, that is where all info is sent. Now on SBC this is typically a UART coming straight off the cpu, so at whatever voltages it can do, usually 3.3V. Having raw messages on the console is good, it means when the machine isn't working, or booting, or whatever - you can always attach to the uart to check the error. The same is true on desk tops, where the console is usually one of the virtual terminals behind the graphical log in.

So this brings up another question, why do usual logins on the console? I usually just use the console for debugging. There are some machines I have where i have never attached a connection to the uart - havn't got round to soldering on a header ...

So guess this is a question in your direction - guess you are doing standard logins on the console? Why is this? Have you set up the console pointing to the wrong place? Or is there a reason for only doing low level input? As theSaint says, if you log in on the ethernet, you probably wouldn't see all these messages ...
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Re: boot messages after login: prompt

Postby Milliways » Wed Oct 17, 2018 11:12 am

$this->bbcode_second_pass_quote('', 'P')robably much of the reason you get messages after the login prompt, is that arch uses systemd to start up the system. This means it starts up init processing in parallel, but taking care of dependencies between different processes.


So do Debian and derived OS such as Ubuntu and Raspbian (and practically every current Linux OS - but these are those I regularly use) but they don't seem to have this problem.

I am logging in at the console with an attached screen and keyboard - no UARTs involved.
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Re: boot messages after login: prompt

Postby summers » Wed Oct 17, 2018 12:01 pm

I'd be tempted to point the console at $this->bbcode_second_pass_code('', ' /dev/ttyS0') or $this->bbcode_second_pass_code('', 'serial0,115200') which is main RPi uart: https://www.raspberrypi.org/documentation/configuration/uart.md. That way you can sill see the messages by attaching a uart to usb cable, but usual logins won't get to see the messages ...

See also https://elinux.org/RPi_Serial_Connection
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