you might try adding setterm --blank 0 --powersave no --powerdown=0 I think i have had luck with that making sure when I turn a monitor back on that the session/screen/output is there and still showing.
I think I have put this sort of stuff in rc.local before to be run at boot. On Wed, Apr 2, 2025 at 2:48 PM Dave Close <d...@compata.com> wrote: > > I wrote: > > > 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? > > Roger Heflin wrote: > > >If the machine does not crash then the serial console is not going to > >have any information that dmesg from ssh does not have. > > >The use-case for the serial console(or kdump) is when the machine > >stops and you can no longer see dmesg output from that boot. > > > >Likely you will need to find the log file for the Wayland/X session > >and look at it. > > Well, neither X nor Wayland has been started since the problem. Without > a display, neither would be of much help. I realize I could try starting > through SSH but haven't felt the need nor can I see the point. I can > start an X application with port forwarding. Note, I do not use the > "graphical" boot and start KDE from the command line. > > Trying to start X through the SSH (-X) connection, I'm told, "Only > console users are allowed to run the X server". Trying to start Wayland > doesn't work either but produces voluminous output. If the serial > connection worked, it would be a console, so maybe Wayland or X could at > least try to start. > > Looking through the dmesg output on the problem machine and on another > machine (also Fedora 41) with the same monitor attached, I don't find > any references to the monitor at all. It appears that monitor detection > doesn't happen until the normal syslog process is running. I do find a > reference to it in /var/log/messages, but only on the working machine. > I don't find any messages indicating failure to find the monitor on the > problem machine. > > Of course, the motivation for trying to get the serial console working > is not really the reason for my post. My reason is, why doesn't the > serial console seem to work? What am I missing in the process? > > I might be focusing on the serial console for Fedora when what I really > need is serial console access to the BIOS boot process. That is the only > way I see to boot from a USB drive (with a different system), just to > see if the problem is a configuration error in Fedora. I now realize > that by the time Fedora starts, that process is done. Maybe I should be > asking if there is a way to get serial access before Fedora. > -- > Dave Close, Compata, Irvine CA +1 714 434 7359 > d...@compata.com dhcl...@alumni.caltech.edu > "A man who says, 'I have learned enough and will learn no further,' > should be considered as knowing nothing at all." --Haile Selassie > > > -- > _______________________________________________ > users mailing list -- users@lists.fedoraproject.org > To unsubscribe send an email to users-le...@lists.fedoraproject.org > Fedora Code of Conduct: > https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: > https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org > Do not reply to spam, report it: > https://pagure.io/fedora-infrastructure/new_issue -- _______________________________________________ users mailing list -- users@lists.fedoraproject.org To unsubscribe send an email to users-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@lists.fedoraproject.org Do not reply to spam, report it: https://pagure.io/fedora-infrastructure/new_issue
