I have an Intel NUC that I want to run headless. Since I couldn't figure out how to configure it without an HDMI monitor and USB keyboard, I configured it with them active.
Next I set up a USB-to-Serial device (ttyUSB0) for my serial login. That is now working.
Now I am trying to get it to work with the HDMI port disconnected.
It doesn't boot with the HDMI port disconnected. If I start up with the HDMI cable connected (and the USB keyboard disconnected) I get a login prompt on the serial port and a text mode prompt on the HDMI monitor.
If I disconnect the HDMI monitor, the serial port crashes and sprays garbage at the teraTerm port.
Any idea what is happening?
Serial port captured below:
ebian GNU/Linux 12 zephDev ttyUSB0
zephDev login:
zephDev login:
zephDev login:
zephDev login: grunzasr
Password:
Linux zephDev 6.1.0-31-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.128-1 (2025-02-07) x86_64
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Sat Mar 22 21:50:06 EDT 2025 on ttyUSB0
grunzasr@zephDev:~$
grunzasr@zephDev:~$
grunzasr@zephDev:~$ echo HDMI connected, about to remove it
HDMI connected, about to remove it
grunzasr@zephDev:~$
grunzasr@zephDev:~$
grunzasr@zephDev:~$ íÿûÿÿÿÿýÿ¿÷ÿÿÿÿÿÿÿÿÿÿÿ½¿ûûÝÿÿÿÿÿ_ÿÿÿÿÿÿ¿ÿÿÿÿûÿÿüÿþþþÿÿþÿ¾»¿þî~ÿýÿ¿ÿ¿ÿÿÿÿÿÿÿÿÿÿÿÿ¿ÿÿÿÿÿÿÿÿþÿþÿþîþëÿþÿÿþüÿþüÿÿ¾ÿÿþÿÿÿÿÿÿÿÿÿïÿûûÿÿÿ÷ÿÿÿÿÿÿÿÿÿÿÿûÿÿÿ÷ÿ¿ÿ÷ÿÿ_ÿÿÿÿÿÿ¿ÿÿûÿÿÿÿÿÿÿÿÿÿÿ¿ÿï~ùýþ¿þ¿¾ÿ¾ÿþþÿÿþÞüÿþÿ¿ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÛÿÿÿÝÿÿÿÿÿÿ¿óßþïç?÷û«þÿÿþÿþÿÿþÿÿ¿ÿþÿÿÿþÿÿÿÿÿÿûÿÿÿÿÿÿÿÿÿÿÿ¿ÿÿïÿûÿþÿüÿþÿþþþþÿþþþþüÿüÿÿþþþÿÿÿ?Úÿúÿþÿþü÷ÿþþþvÿþïýÿÿÿÿÿÿÿþÿÿÿÿÿÿßûÿÿÿÿÿÿûÿÿÿÿÿ÷ÿÿÿÿÿûÿÿÿÿÿ÷ÿÿ»«¯·µûûþºó¿ÿþ÷ÿþÿü¿þþÿþÿþÿþÿÿÿûÿÿÿÿÿÿÿÿÛÿÿÿûýý7ÿþþþûüÿÿþÿÿþ«ÿÿÿÿÿÿÿÿÿÿoÿÿÿÿÿÿÿÿÿ·¿Ýÿÿÿÿ_ÿÿÿÿÿÿ¿ÿÿûÿÿÿÿÿÿÿÿÿ¿»¼ÿî~ùþ¾þ¿÷þ¿ÿüÿÿÿÿþÿÿþÿ¿ÿÿÿßÿÿÿÿÿÿÿÿûÿÿ_ÿÿÿÿÿÿ¿ÿíÿ»ÿÿýÿ¾¿jÿÿ¿¿ÿ]ÿÝÿ¶ûþÿþ_þÿþÿþÿ¿ÿþÿÿÿÿÿ·ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ¿ÿÿÿÿÿÿÿÿÿÿÿÿþÿþûþüÿ¿×¾óßþ=þÿÿÿþÿþþÿþÿ¿ÿÿÿÿÿÿÿÿÿÿÿÿÿÿ÷ÿÿÿÿÿÿÿÿÿÿÿ÷÷ÿÿÿÿÿÿÿÿýÿÿÿþüÿþÿþãÿþüÿþøÿþÿÿÿóÿþÿþÿ÷ÿÿ¿}ÿþûÿÿ÷ÿÿÛÿÿÿÿÿ÷ÿÿÿÿÿÿÿÿÿÿÿÿÿ÷ÿÿÿÿýý«û«ëûûã«ûÿûûëùûÿþÿÿÿöÿÿÿÿÿÿþþÿÿÿýýÿÿÿûÛ÷ûÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿßÿÿÿÛÛûÿýÿÿÿÿÿÿûÿÿÿÿÿÿÿÿÿÿÿÿ¿ÿÿÿûÿûÿÿÿûûûÿþoÿÿ«¶5õµëýÿý¯ïßÿÿÿÿÿûÿÿÿÿÿÿÿ÷ÿÿÿ¿ÿÿÿûÿûÿÿÿûûóû¼óþþ~û¿¾µãëû«ÿ¿ûÿþÿýÿÿÿÿÿÿ¿ÿÿÿÿýÿÿÿÿ½ýÿÿßÛÿÿÿ¿þþþþÿÿþÿüþÿÿþþþþüþÿýýýÿþÿÿÿÿûÿþïÿÿ÷ÿÿ¿ÿÿÿ¿ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿýÿþþþþþ{ýÿüÿÿÿÿÿ¿ÿÿÿÿÿÿÿþ÷ÿÿÿ¿ÿÿûÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿõÿÿÿÿûÿÿíýýÿÿÿÿÿÿûÿÿÿÿÿÿ¿ÿþþþÿþÿÿçÿþÿÿ¾ÿûÿþûþÿÿÿÿÿÿÿÿÿÿûÿÿÿÿÿÿÿÿÿÿ÷ÿÿÿ¿ÿÿû¾ûÿÿn»¾Þ¿¿ÿûúÿûþÿÿï¿ÿýÿÿÿÿÿÿÿÿÿÿÿ÷ÿÿÿ¿ÿÿÿûÿûÿÿÿûû¿û¿ÿÍþþn~¾5?û«üûµÿ¿ÿÿýýýÿÿÿÿÿÿÿ¿ÿÿÿûÿÿÿÿÿ÷ÿÿÿ¿ÿÿÿûÿûÿÿÿûûûû¾ÿ?ü~³«û«¾»ëþ»«»½¿ûÿÿûïýÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ÷ÿÿÿ¿ÿÿÿûÿÿo»¿Þûã?¿û>ÿóÿÍþÿûýÿû½¿ÿÿÿÿÿ÷ÿÿïÿÿýýýÿÿÿÿÿÿûÿÿÿÿÿÿÿÿÿÿ÷ÿþ¿þûþ?ýÿþû¾¿þÿÿ»¿ß¿¿ÿ¿ÿÿÿÿ¿ÿÿ¿ÿÿÿÿïÿÿÿÿÿýýÿÿÿÿÿÿûþÿÿ¿¾ÿþþüÿþÿþ÷ÿþüÿ¾ÿÿ¿þû¿ûÿûÿÿÿ¿ÿûÿÿÿ¿ÿïþþþ¾ÿýýýÿþþüþþ{ýÿþÿÿÿÿÿÿÿÿÿÿÿ?ÿÿÿ¿ÿÿÿûÿûÿÿûûÿÿþþ«?ÿã«ÿûµû«¿»«¯ÿ¿ÿþÿþïÿÿÿÿÿÿÿûÿÿÿÿÿÿÿÿÿÿÿÿûÿÿÿÿÿÿÿÿÿÿÿ÷ÿÿÿ¿ýøû¼¿ÿüÿn·ó¿¿?ÿ¿þÿûý¿µûÿÿÿÿÿÿ¿ÿÿ¿ÿÿÿïÿÿÿÿÿÿ»ÿýýýÿÿÿþóùÿþÿþßþø¾¿ÿþþþÿÿþçÿþÿÿ¿ÿÿÿ
Serial port console is now not functioning; however, a xrdp session over Ethernet is still up. Any ideas where I should be looking to figure out what went wrong?
grunzasr@zephDev:~$ ps auxww | grep -i getty
root 654 0.0 0.0 5872 1056 tty1 Ss+ 21:54 0:00 /sbin/agetty -o -p -- \u --noclear - linux
grunzasr 1380 0.0 0.0 6332 2148 pts/0 S+ 22:06 0:00 grep -i getty
grunzasr@zephDev:/etc/default$ cat grub | grep -v \#
GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
GRUB_CMDLINE_LINUX=""
grunzasr@zephDev:/etc/default$ ps aux | grep -i getty
root 654 0.0 0.0 5872 1056 tty1 Ss+ 21:54 0:00 /sbin/agetty -o -p -- \u --noclear - linux
grunzasr 1386 0.0 0.0 6332 2024 pts/0 S+ 22:09 0:00 grep -i getty
grunzasr@zephDev:/etc/default$ sudo kill -9 654
grunzasr@zephDev:/etc/default$ ps aux | grep -i getty
root 1394 0.0 0.0 5872 1036 tty1 Ss+ 22:09 0:00 /sbin/agetty -o -p -- \u --noclear - linux
grunzasr 1399 0.0 0.0 6332 2092 pts/0 S+ 22:09 0:00 grep -i getty