I have a machine running Fedora 41 which has stopped providing video
for its console. Of course, the problem could be hardware, but there
is no clear evidence of that. I am able to access the machine with SSH
so I know it is working. I don't find any indication of a problem in
log files. To help diagnose the issue, I'd like to access its console
through its serial interface. (The machine does have a DB9 serial
connector and I have verified that it works properly.)
I have connected a serial to USB adapter to the machine's serial port
and connected the other end of the USB cable to a laptop (also running
Fedora 41). On the laptop, I've started putty and selected a serial
connection to ttyUSB0 at speed 38400. On the problem machine, I've run
the following commands as root with no errors reported.
# grubby \
--args="systemd.journald.forward_to_console=1 \
console=ttyS0,38400 console=tty1" --update-kernel=ALL
# # The line continuation above is only for readability.
# # The actual command was all one line.
# grubby --set-default=/boot/vmlinuz-6.13.9-200.fc41.x86_64
# grub2-mkconfig -o /boot/grub2/grub.cfg
# grub2-install /dev/sda
# reboot
I then SSH into the problem machine and check for agetty.
# ps -ef | grep [g]etty
root 1429 1 0 21:55 tty1 00:00:00
/sbin/agetty -o -p -- \u --noclear - linux
root 1430 1 0 21:55 ttyS0 00:00:00
/sbin/agetty -o -p -- \u --keep-baud 115200,57600,38400,9600 - vt220
# Again, lines are split and condensed here only for readability.
After all this, I get no output on the putty connection and no response
when attempting any entry. I've also tried the other listed baud rates.
Is there any obvious step I've missed? Is there a better way to do this?
--
Dave Close, Compata, Irvine CA +1 714 434 7359
d...@compata.com dhcl...@alumni.caltech.edu
"Some problems are so complex that you have to be highly intelligent
and well informed just to be undecided about them." -- Laurence Peter
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--
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