55 lines
		
	
	
		
			1.1 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			55 lines
		
	
	
		
			1.1 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
{ config, lib, ... }:
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with lib;
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let
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  cfg = config.powerManagement.scsiLinkPolicy;
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  kernel = config.boot.kernelPackages.kernel;
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  allowedValues = [
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    "min_power"
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    "max_performance"
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    "medium_power"
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    "med_power_with_dipm"
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  ];
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in
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{
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  ###### interface
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  options = {
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    powerManagement.scsiLinkPolicy = mkOption {
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      default = null;
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      type = types.nullOr (types.enum allowedValues);
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      description = ''
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        SCSI link power management policy. The kernel default is
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        "max_performance".
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        </para><para>
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        "med_power_with_dipm" is supported by kernel versions
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        4.15 and newer.
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      '';
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    };
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  };
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  ###### implementation
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  config = mkIf (cfg != null) {
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    assertions = singleton {
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      assertion = (cfg == "med_power_with_dipm") -> versionAtLeast kernel.version "4.15";
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      message = "med_power_with_dipm is not supported for kernels older than 4.15";
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    };
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    services.udev.extraRules = ''
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      SUBSYSTEM=="scsi_host", ACTION=="add", KERNEL=="host*", ATTR{link_power_management_policy}="${cfg}"
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    '';
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  };
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}
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