Thanks, Rich, for taking the (google-)time.
I tested some ACPI boot codes before this thread. Unfortunately, all without success.
But now, I have news ...
I have drawn my attention to the line before the error message :
i801_smbus 0000:00:1f.3: PCI INT B -> GSI 19 (level, low) -> IRQ 19
I found out, that this is generated when loading the i2c_i801 kernel module. After blacklisting this module by boot code (blacklist=i2c_i801), the error is gone.
Okay, but now I am faced with the choice: ACPI or i2c_i801?
Frankly, I do not know both ...
I've read, that you need i2c for e.g. lm_sensors - but anyway lm_sensors finds no sensors in my notebook:
tc@box:~$ sudo sensors-detect
...
...
...
Sorry, no sensors were detected.
This is relatively common on laptops, where thermal management is handled by ACPI rather than the OS.
I do not even know if there is a i2c bus is in my notebook ... but I'm assuming that the module is loaded only if there is such a bus ...
On the other hand, I can not turn off (remotely) the notebook without ACPI.
Therefore I tend to turn i2c off. Is this dangerous?