Kernel was downgraded from 6.6 to 6.8 when I updated today

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1

Hello,

I have a 9950xt witrh NixOS and ZFS, and i’m running with the config below, but when I ran nixos-rebuild --upgrade boot today, the kernel was downgraded from 6.8 to 6.6 again? Any idea why?

Since I’m running a really new CPU I want to run the latest kernel available, because AMD has pushed a lot of patches recently.

  # Use the systemd-boot EFI boot loader.
  boot.loader.systemd-boot.enable = true;
  boot.loader.efi.canTouchEfiVariables = true;
  nixpkgs.config.allowUnfree = true;
  hardware.enableAllFirmware = true;
  boot.kernelPackages = config.boot.zfs.package.latestCompatibleLinuxPackages;
  boot.kernelModules = [ "vfio" "vfio_iommu_type1" "vfio_pci" "vfio_virqfd" "ip_vs_wrr" "ip_vs_sh" "ip_vs" "ip_v
s_rr" "nvme" "nvme-tcp" "nvme-fc" "nvme-rdma" ];
  boot.blacklistedKernelModules = [ "cp210x" ];
  boot.kernelParams = [ "panic=1" "pcie_acs_override=downstream,multifunction" "rd.driver.blacklist=nvidia" "mod
probe.blacklist=nvidia" "rd.driver.blacklist=nouveau" "modprobe.blacklist=nouveau" "video=efifb:off" "pci=reallo
c" "initcall_blacklist=sysfb_init" "rd.driver.pre=vfio-pci" "vfio-pci.ids=10de:2702,10de:22bb" "nvme_core.multip
ath=N" "processor.max_cstate=5" ];
  boot.kernelPatches = [ {
    name = "add-acs-overrides";
    patch = ./add-acs-overrides.patch;
  } ];
  hardware.cpu.amd.updateMicrocode = true;
  powerManagement.cpuFreqGovernor = "performance";
2

If I had to guess:

boot.kernelPackages = config.boot.zfs.package.latestCompatibleLinuxPackages;

was changed from pointing to kernel 6.8 to 6.6 ZFS doesn’t generally support the latest kernel releases and I think 6.8 is no longer supported upstream, so 6.6 is now the latest supported kernel that ZFS supports.

6.6 is an LTS kernel, 6.8 isn’t, so 6.6 ends up being supported for longer than 6.8.

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3

Hmm, I see, thats too bad!
I’m running Arch on another machine, and there I can run zfs with 6.10 without any problems. I guess i’ll just have to wait. :pensive:

4

If you’re running stable NixOS, (guessing here) the ZFS module probably doesn’t get updated as frequently as it would be in Arch and therefore doesn’t contain the kernel 6.10 support.

If you’re running NixOS Unstable I would assume it would eventually be updated.

1 Like
5

Ah, yes! On my arch machine I was running zfsonlinux-git, but my nixos is a server and I don’t want to run any unstable stuff there.

So i’ll just have to wait.

6

Heavy asterisk on that “without any problems”. ZFS will often build on newer kernels when it isn’t tested or supported, and that can easily lead to nasty bugs. The META file in the ZFS repo tells you what the latest supported kernel is, but if it’s not in an official release I wouldn’t consider it particularly well tested.

2 Likes
7

Yeah, maybe! All my important files are stored on my Truenas anyway!