Hello, There are some devices that when present will cause the "coldplug all devices" stage at boot to fail. On a normally installed system only an error is reported in the journal and logs during boot but the system boots normally and the device also functions normally. But on debian installer media such as netinst or the Debian live installer images, this failure causes a crash and prevents users with such devices from being able to run the debian installer from those installer media.
This was reported as a bug over a year and a half ago on BTS, and the bug is currently assigned to linux, that is, the Debian Linux Kernel Team. The problem has also been documented on the Debian installation reports pseudo package. One of the Debian kernel developers suggested a solution of increasing the uevent buffer in the kernel from 2k to 4k, and tests showed that the patch of increasing the buffer in the kernel solved the coldplug all devices problem. That bug of too small a buffer size is in the upstream part of the Linux kernel, so the bug should probably be forwarded to the Linux kernel, and the person who reported the bug (not me) did report the bug to the Linux kernel, as well as to the Debian BTS. But neither Debian nor the Linux kernel has acted on the bug report to try to fix it, except for the suggestion that a Debian kernel developer made to increase the uevent buffer size in the kernel over a year ago and another suggestion from another Debian maintainer or developer who gave me advice on how to document the problem in the installer so the problem could be included on the debian installer errata page, which is why I made the installation report. But the debian installer errata page also was never updated even though I made that installation report over six months ago: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1005308 https://www.debian.org/releases/bullseye/debian-installer/#errata I also tested a current Fedora Workstation 36 installation in the same computing environment, which is a virtual environment, and it exhibited some of the same symptoms that are fixed by the increase of the uevent buffer in the kernel, but on Fedora at the "coldplug all devices" stage during boot, the device that was creating data too big for the uevent buffer in the kernel on both Fedora and Debian did not cause an error message to be printed to the journal and boot logs on Fedora and also on Fedora the live and netinst images do not crash, but on Debian these negative things do happen. Finally, another workaround to make the Debian live image or the Debian netinst image bootable with the problematic device was to edit the udev startup script on the installer image (I think it was in the initrd) to keep it from causing the catastrophic crash when the "coldplug all devices" command is executed, which is actually done, IIUC, by the udevadm executable file. So my question is about udevadm which I think is the command that is executed during boot to coldplug all devices: Is there a way to write the udev rules configuration files so that a particular kind of device that perhaps is not really what I would call "udev-aware" could be excluded from the set of devices that are coldplugged at boot? I am only asking here in case someone knows the answer and is willing to tell me, but if no one here can answer my question I will probably be able to figure it out by examining the differences between the Fedora and Debian udev rules for the various kinds of devices. I suspect that Fedora wrote its udev rules so such devices that are not really the kind of devices that need to be udev-aware and that cause problems or error messages are excluded from the "coldplug all devices" stage of boot. For reference, I am talking about Bug #983357 which is the primary bug report: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=983357 Thanks in advance for any tips from the udev experts. Kind regards, Chuck
