[Bug 2150769] Re: There is a conflict between the pc-kernel snap and additional firmware packages

** Tags added: kernel-daily-bug -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2150769 Title: There is a conflict between the pc-kernel snap and additional firmware packages Status in linux package in Ubuntu: Confirmed Status in linux-firmware-intel-wireless package in Ubuntu: Confirmed Bug description: I described in detail here, in case I miss anything in this description: https://discourse.ubuntu.com/t/the-pc-kernel-snap- on-26-04-prevents-users-from-installing-additional-firmware/81404 This bug report is pretty wordy so here's a top-line summary: 1. The pc-kernel snap uses an unfortunately unreliable method of including firmware, which means some firmware gets missed 2. The apt dependencies of `boot-managed-by-snapd` preclude installing `linux-firmware` but do not preclude installing any other firmware packages making it possible to break your system in a pretty dramatic way that many users might have a very difficult time figuring out or resolving. Reproduction steps: 1. Install Ubuntu using the `pc-kernel` snap rather than apt kernel packages 2. Install the `linux-firmware-intel-wireless` package Okay, now on to the verbose part of the bug report which I hope is at least partially understandable. Circumstance: 1. I'm running Ubuntu 26.04 using the pc-kernel snapo (because of hardware FDE I guess) 2. My laptop has a pretty new Arrow Lake chipset with an Intel wifi adapter 3. My wifi doesn't work What I discovered while debugging: the `iwlwifi` module won't load properly because it can't find the firmware file it wants, as it is not present in the `pc-kernel` snap, so wifi doesn't work. This took me in a few different directions and this is what I found: * Unspecified incompatibility between pc-kernel and additional firmware packages First, the pc-kernel snap creates symlinks to everything in its 'firmware' directory into the filesystem that gets mounted at /usr/lib/firmware, but it links everything at the top-level. That means firmware can be added to e.g. /usr/lib/firmware/somefile.fw, because that's a directory, but not /usr/lib/firmware/intel/somefile.fw because /usr/lib/firmware/intel is a symlink to a directory on the squashfs filesystem. This means that installing the `linux-firmware-intel-wireless` package, which has the firmware I need: 1. Breaks when trying to install because it tries to write some files to /usr/lib/firmware/intel/ 2. Refuses to uninstall until it's installed correctly, because dpkg recognizes it as being in an extremely broken state. I say 'unspecified' because `boot-managed-by-snapd` explicitly conflicts with `linux-firmware` (showing the intention to not allow both at once), but it does not conflict with any additional firmware packages. * Incomplete firmware inventory in the pc-kernel snap I dug into it a bit and found that the pc-kernel snap builds using the following steps: 1. Get the kernel and the modules together 2. Ask each module what firmware it wants (via `modinfo`) 3. Bundle those firmwares into the pc-kernel snap Unfortunately, for whatever reason, the `iwlwifi` firmware does not specify the firmware that my system seems to insist on, which is `bz-b0-fm-c0-c101.ucode`, so it does not get included into the pc- kernel snap. The `linux-firmware-intel-wireless` debian package *does* include this firmware, presumably because it just includes all available Intel wireless firmware unconditionally. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-14-generic (not installed) ProcVersionSignature: Ubuntu 7.0.0-14.14-generic 7.0.0 Uname: Linux 7.0.0-14-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC2: dan 6392 F.... wireplumber /dev/snd/controlC1: dan 6392 F.... wireplumber /dev/snd/controlC0: dan 6392 F.... wireplumber /dev/snd/seq: dan 6354 F.... pipewire CasperMD5CheckMismatches: ./EFI/boot/bootx64.efi ./EFI/boot/grubx64.efi ./EFI/boot/mmx64.efi CasperMD5CheckResult: fail CurrentDesktop: ubuntu:GNOME Date: Thu Apr 30 10:29:41 2026 MachineType: Dell Inc. Dell Pro Max 14 Premium MA14250 ProcEnviron: LANG=en_US.UTF-8 PATH=(custom, no user) SHELL=/bin/zsh TERM=xterm-ghostty XDG_RUNTIME_DIR=<set> ProcFB: 0 i915drmfb ProcKernelCmdLine: snapd_recovery_mode=run console=ttyS0,115200n8 console=tty1 panic=-1 quiet splash snapd.xkb="us,pc105,," RebootRequiredPkgs: Error: path contained symlinks. SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/11/2025 dmi.bios.release: 1.7 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.7.1 dmi.board.name: 06XRHN dmi.board.vendor: Dell Inc. dmi.board.version: A02 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.ec.firmware.release: 1.6 dmi.modalias: dmi:bvnDellInc.:bvr1.7.1:bd12/11/2025:br1.7:efr1.6:svnDellInc.:pnDellProMax14PremiumMA14250:pvr:rvnDellInc.:rn06XRHN:rvrA02:cvnDellInc.:ct10:cvr:sku0D32:pfaDellProMaxLaptops: dmi.product.family: Dell Pro Max Laptops dmi.product.name: Dell Pro Max 14 Premium MA14250 dmi.product.sku: 0D32 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2150769/+subscriptions