Control: retitle -1 Console hangs on 6.1.0-39 while 6.1.0-37 works fine Hello Chris, On Wed, Nov 12, 2025 at 03:23:21PM +0100, Chris Mair wrote: > tried all three, nothing changes the stuck screen as shown on the attached VGA monitor: > > - `echo t > /proc/sysrq-trigger` doesn't show on the monitor, but shows debug log correctly in the dmesg output, > > - `echo "Debian is great" > /dev/tty1` doesn't show on the monitor, > > - pressing Alt+PrtSc+t doesn't show on the monitor and logs 'sysrq: This sysrq operation is disabled.' in the dmesg output. > > > Please excuse if I repeat information: That's fine, when working on several bugs on and off it's easy to miss some relevant info. > The kernels that works fine (up to 6.1.0-37-amd64), show the boot log > and then at some point visibly change the screen resolution, the font > gets visibly thinner, the screen is cleared and the text-login prompt > appears. > > Later kernels (from 6.1.0-39-amd64 and what I'm using right now > 6.1.0-40-amd64) freeze the screen at exactly the > moment that switch occurs. > > To me, it looks like whatever that switch does, just completely > freezes screen output. But, what was logged up to > that point stays on screen indefinitely (as in the photo). It's not > that the screen blanks because somehow the VGA signal > is wrong or lost, it keeps on showing that last screen content frozen > in time. I think the most useful way forward would be to bisect that problem. The idea is to check the kernel commit that is approximately in the middle between 6.1.0-37 (the newest known working kernel) and 6.1.0-39 (the oldest known broken kernel). Depending on the outcome of the test there is either a newer working one or an older broken. That can be iterated until the offending commit is identified. To do that, the following has to be done. If you fail to follow my instructions (because they are too short or don't work as expected) please report that back. git clone --single-branch -b linux-6.1.y https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git cd linux-stable git checkout v6.1.140 # corresponds to 6.1.0-37 cp /boot/config-$(uname -r) .config yes '' | make localmodconfig make savedefconfig mv defconfig arch/x86/configs/my_defconfig make my_defconfig make -j $(nproc) bindeb-pkg You might need to install some additional packages, the ones that are typically missing are: build-essential bc bison flex libelf-dev libssl-dev This results in a package containing a 6.1.140 kernel. Install that, boot it. The expectation is that this works fine. Then confirm that 6.1.148 is also bad when you build it: cd linux-stable git checkout v6.1.148 make my_defconfig make -j $(nproc) bindeb-pkg install and boot that. If there are no suprises (i.e. 6.1.140 is good and 6.1.148 has that hanging console) do: cd linux-stable git bisect start v6.1.148 6.1.140 make my_defconfig make -j $(nproc) bindeb-pkg Install and test that kernel and depending on it showing the problem or not do: git bisect bad or git bisect good which checks out the next kernel to test. Iterate until the git bisect command emits the offending commit. This needs ~11 iterations. Please uninstall these test kernels at the end again to make sure that the Debian kernel is used. Depending on your partitioning you might also have to uninstall kernel earlier to have enough disk space in /boot and /boot/efi to install the next test kernel. (Some thoughts I had before considering that bisecting is the right thing to do: Your machine has two VGA adapters, which is the relevant? You could try to reload the driver. For my machine using the i915 driver this would work as follows: root@hostname:~# cd /sys/module/i915/drivers/pci\:i915/ root@hostname:/sys/module/i915/drivers/pci:i915# ls -la total 0 drwxr-xr-x 2 root root 0 Nov 7 23:30 . drwxr-xr-x 31 root root 0 Nov 7 20:47 .. lrwxrwxrwx 1 root root 0 Nov 15 18:34 0000:00:02.0 -> ../../../../devices/pci0000:00/0000:00:02.0 --w------- 1 root root 4096 Nov 15 18:34 bind lrwxrwxrwx 1 root root 0 Nov 15 18:34 module -> ../../../../module/i915 --w------- 1 root root 4096 Nov 15 18:34 new_id --w------- 1 root root 4096 Nov 15 18:34 remove_id --w------- 1 root root 4096 Nov 15 18:34 uevent --w------- 1 root root 4096 Nov 15 18:34 unbind root@hostname:/sys/module/i915/drivers/pci:i915# echo 0000:00:02.0 > unbind; sleep 3; echo 0000:00:02.0 > bind However it's not clear what we would learn from that. Might only be an additional info when reporting your problem upstream.) Best regards Uwe
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