When booting up, the development board outputs debug messages through the ttyTCU0 serial port, I want to make the debug messages not output, or use the tty1 virtual serial port to do so, I tried modifying the grub and failed, and also tried setting the serial port to disable in the BIOS, which also failed.
Hi 13998191106,
What’s the Jetpack version in use?
ttyTCU is Tegra Combined UART, which means that it output the debug message from different firmware (MB1/MB2/SPE/UEFI/Kernel…etc). We don’t suggest to modify or disable it since it’s no an easy work and we’ve not verified that yet.
May I know what’s your reason to do this so?
Only “sort of” related to your question, here is some information you might find useful…
None of the “/dev/tty#” terminals are virtual. So “/dev/tty1” is not virtual.
If you are already in a pure text console, then the key bindings for ALT+F1 through ALT+F6 would usually be set to go to a local (non-virtual terminal). Note that usually ALT+F1 has another use, and that often the range of available local terminals is ALT+F2 through ALT+F6.
If you are in the GUI, then you also use CTRL key to get to local terminals. So CTRL+ALT+F2 would get to the second local terminal.
During boot the ALT+F1 through ALT+F6 would be set up to run a getty (or variant) login program. That’s the multi-user.target (a.k.a., “text mode”). If GUI is run, then reaching graphical.target replaces the ALT+F1 to use the GUI login manager instead of a getty.
During boot, up through multi-user.target, the debug messages normally go to /dev/tty1 and to the serial console (in this case ttyTCU0). When the GUI login manager replaces the getty in tty1, then that logging disappears. The program that displayed that information is gone.
Also, there is a tty1 during most of boot. This is single user mode. When transitioning to multi-user.target the other local terminals (tty2 through tty6) begin running. Even during boot stages, before Linux ever starts, the serial console is running. Boot content has its own serial console program which coincidentally goes the same UART with the same settings as when Linux loads and starts running. Local tty1 does not have that property.
Also, Jetsons do not have a BIOS. Jetsons do have the equivalent in software, but you cannot manipulate it the same way. Some environment can be changed through UEFI settings, *but this requires the serial console on ttyTCU0. Example settings are some boot device search order settings. It is easy to disable serial console through ordinary methods once Linux has been reached, but doing so in boot stages is generally more difficult and elaborate. This also disables what access you have to UEFI and changes would require flashing the system again. Not a good idea.
Knowing what was done to GRUB might help someone to answer, but it is possible you’ll have to flash again for some circumstances. The question cannot be answered in terms of BIOS because there is none.
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