Change:
Steps to reproduce the behavior: after update Add any other context about the problem here. <!-- Please @ people who are in the list of the offending package or module. If in doubt, check for whoever last touched something. --Please run and paste the result. But I am using flakes and following unstable. Add a :+1: [reaction] to [issues you find important]. [reaction]: [issues you find important]:
It was an intentional breaking change
TY.
To sum up, is non-optional and must be set now: When , use open source NVIDIA kernel module, this is now recommended by NVIDIA, but it doesn't work with older drivers. When , use proprietary kernel module. This is needed for people with older NVIDIA cards. More information:

Discussion:
cfg = config.hardware.nvidia; <ins> useOpenModules = cfg.open == true; </ins> pCfg = cfg.prime; syncCfg = pCfg.sync; offloadCfg = pCfg.offload; reverseSyncCfg = pCfg.reverseSync; primeEnabled = syncCfg.enable || reverseSyncCfg.enable || offloadCfg.enable; busIDType = lib.types.strMatching "([[:print:]]+[:@][0-9]{1,3}:[0-9]{1,2}:[0-9])?"; <del> ibtSupport = cfg.open || (nvidia_x11.ibtSupport or false); </del> <ins> ibtSupport = useOpenModules || (nvidia_x11.ibtSupport or false); </ins> settingsFormat = pkgs.formats.keyValue { }; in {

open = lib.mkOption { example = true; description = "Whether to enable the open source NVIDIA kernel module."; <del> type = lib.types.bool; </del> <ins> type = lib.types.nullOr lib.types.bool; default = if lib.versionOlder nvidia_x11.version "560" then false else null; </ins> defaultText = lib.literalExpression '' <del> lib.mkIf (lib.versionOlder config.hardware.nvidia.package.version "560") false </del> <ins> if lib.versionOlder config.hardware.nvidia.package.version "560" then false else null </ins> ''; }; gsp.enable = lib.mkEnableOption '' the GPU System Processor (GSP) on the video card '' // { <ins> default = useOpenModules || lib.versionAtLeast nvidia_x11.version "555"; </ins> defaultText = lib.literalExpression '' <del> config.hardware.nvidia.open || lib.versionAtLeast config.hardware.nvidia.package.version "555" </del> <ins> config.hardware.nvidia.open == true || lib.versionAtLeast config.hardware.nvidia.package.version "555" </ins> ''; }; };

assertion = !(nvidiaEnabled && cfg.datacenter.enable); message = "You cannot configure both X11 and Data Center drivers at the same time."; } <ins> { assertion = cfg.open != null; message = '' You must configure `hardware.nvidia.open` on NVIDIA driver versions >= 560. It is suggested to use the open source kernel modules on Turing or later GPUs (RTX series, GTX 16xx), and the closed source modules otherwise. ''; } </ins> ]; boot = { blacklistedKernelModules = [

extraPackages32 = [ nvidia_x11.lib32 ]; }; environment.systemPackages = [ nvidia_x11.bin ]; <del> hardware.nvidia.open = lib.mkIf (lib.versionOlder nvidia_x11.version "560") (lib.mkDefault false); hardware.nvidia.gsp.enable = lib.mkDefault (cfg.open || lib.versionAtLeast nvidia_x11.version "555"); </del> }) # X11

} { <del> assertion = cfg.open -> (cfg.package ? open); </del> <ins> assertion = useOpenModules -> (cfg.package ? open); </ins> message = "This version of NVIDIA driver does not provide a corresponding opensource kernel driver."; } { <del> assertion = cfg.open -> cfg.gsp.enable; </del> <ins> assertion = useOpenModules -> cfg.gsp.enable; </ins> message = "The GSP cannot be disabled when using the opensource kernel driver."; }

"L+ /run/nvidia-docker/extras/bin/nvidia-persistenced - - - - ${nvidia_x11.persistenced}/origBin/nvidia-persistenced"; boot = { <del> extraModulePackages = if cfg.open then [ nvidia_x11.open ] else [ nvidia_x11.bin ]; </del> <ins> extraModulePackages = if useOpenModules then [ nvidia_x11.open ] else [ nvidia_x11.bin ]; </ins> # nvidia-uvm is required by CUDA applications. kernelModules = lib.optionals config.services.xserver.enable [

# With the open driver, nvidia-uvm does not automatically load as # a softdep of the nvidia module, so we explicitly load it for now. # See https://github.com/NixOS/nixpkgs/issues/334180 <del> ++ lib.optionals (config.services.xserver.enable && cfg.open) [ "nvidia_uvm" ]; </del> <ins> ++ lib.optionals (config.services.xserver.enable && useOpenModules) [ "nvidia_uvm" ]; </ins> # If requested enable modesetting via kernel parameters. kernelParams = lib.optional (offloadCfg.enable || cfg.modesetting.enable) "nvidia-drm.modeset=1" ++ lib.optional ((offloadCfg.enable || cfg.modesetting.enable) && lib.versionAtLeast nvidia_x11.version "545") "nvidia-drm.fbdev=1" ++ lib.optional cfg.powerManagement.enable "nvidia.NVreg_PreserveVideoMemoryAllocations=1" <del> ++ lib.optional cfg.open "nvidia.NVreg_OpenRmEnableUnsupportedGpus=1" </del> <ins> ++ lib.optional useOpenModules "nvidia.NVreg_OpenRmEnableUnsupportedGpus=1" </ins> ++ lib.optional (config.boot.kernelPackages.kernel.kernelAtLeast "6.2" && !ibtSupport) "ibt=off"; # enable finegrained power management