135 lines
		
	
	
		
			4.6 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			135 lines
		
	
	
		
			4.6 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
# This module allows the test driver to connect to the virtual machine
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# via a root shell attached to port 514.
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{ config, lib, pkgs, ... }:
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with lib;
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let
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  kernel = config.boot.kernelPackages.kernel;
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  # FIXME: figure out a common place for this instead of copy pasting
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  serialDevice = if pkgs.stdenv.isi686 || pkgs.stdenv.isx86_64 then "ttyS0"
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        else if pkgs.stdenv.isArm || pkgs.stdenv.isAarch64 then "ttyAMA0"
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        else throw "Unknown QEMU serial device for system '${pkgs.stdenv.system}'";
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in
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{
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  # This option is a dummy that if used in conjunction with
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  # modules/virtualisation/qemu-vm.nix gets merged with the same option defined
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  # there and only is declared here because some modules use
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  # test-instrumentation.nix but not qemu-vm.nix.
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  #
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  # One particular example are the boot tests where we want instrumentation
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  # within the images but not other stuff like setting up 9p filesystems.
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  options.virtualisation.qemu.program = mkOption { type = types.path; };
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  config = {
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    systemd.services.backdoor =
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      { wantedBy = [ "multi-user.target" ];
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        requires = [ "dev-hvc0.device" "dev-${serialDevice}.device" ];
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        after = [ "dev-hvc0.device" "dev-${serialDevice}.device" ];
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        script =
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          ''
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            export USER=root
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            export HOME=/root
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            export DISPLAY=:0.0
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            source /etc/profile
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            # Don't use a pager when executing backdoor
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            # actions. Because we use a tty, commands like systemctl
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            # or nix-store get confused into thinking they're running
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            # interactively.
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            export PAGER=
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            cd /tmp
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            exec < /dev/hvc0 > /dev/hvc0
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            while ! exec 2> /dev/${serialDevice}; do sleep 0.1; done
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            echo "connecting to host..." >&2
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            stty -F /dev/hvc0 raw -echo # prevent nl -> cr/nl conversion
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            echo
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            PS1= exec /bin/sh
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          '';
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        serviceConfig.KillSignal = "SIGHUP";
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      };
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    # Prevent agetty from being instantiated on ${serialDevice}, since it
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    # interferes with the backdoor (writes to ${serialDevice} will randomly fail
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    # with EIO).  Likewise for hvc0.
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    systemd.services."serial-getty@${serialDevice}".enable = false;
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    systemd.services."serial-getty@hvc0".enable = false;
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    boot.initrd.preDeviceCommands =
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      ''
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        echo 600 > /proc/sys/kernel/hung_task_timeout_secs
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      '';
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    boot.initrd.postDeviceCommands =
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      ''
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        # Using acpi_pm as a clock source causes the guest clock to
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        # slow down under high host load.  This is usually a bad
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        # thing, but for VM tests it should provide a bit more
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        # determinism (e.g. if the VM runs at lower speed, then
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        # timeouts in the VM should also be delayed).
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        echo acpi_pm > /sys/devices/system/clocksource/clocksource0/current_clocksource
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      '';
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    boot.postBootCommands =
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      ''
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        # Panic on out-of-memory conditions rather than letting the
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        # OOM killer randomly get rid of processes, since this leads
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        # to failures that are hard to diagnose.
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        echo 2 > /proc/sys/vm/panic_on_oom
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        # Coverage data is written into /tmp/coverage-data.
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        mkdir -p /tmp/xchg/coverage-data
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      '';
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    # If the kernel has been built with coverage instrumentation, make
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    # it available under /proc/gcov.
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    boot.kernelModules = [ "gcov-proc" ];
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    # Panic if an error occurs in stage 1 (rather than waiting for
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    # user intervention).
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    boot.kernelParams =
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      [ "console=${serialDevice}" "panic=1" "boot.panic_on_fail" ];
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    # `xwininfo' is used by the test driver to query open windows.
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    environment.systemPackages = [ pkgs.xorg.xwininfo ];
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    # Log everything to the serial console.
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    services.journald.extraConfig =
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      ''
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        ForwardToConsole=yes
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        MaxLevelConsole=debug
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      '';
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    # Don't clobber the console with duplicate systemd messages.
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    systemd.extraConfig = "ShowStatus=no";
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    boot.consoleLogLevel = 7;
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    # Prevent tests from accessing the Internet.
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    networking.defaultGateway = mkOverride 150 "";
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    networking.nameservers = mkOverride 150 [ ];
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    systemd.globalEnvironment.GCOV_PREFIX = "/tmp/xchg/coverage-data";
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    system.requiredKernelConfig = with config.lib.kernelConfig; [
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      (isYes "SERIAL_8250_CONSOLE")
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      (isYes "SERIAL_8250")
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      (isEnabled "VIRTIO_CONSOLE")
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    ];
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    networking.usePredictableInterfaceNames = false;
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    # Make it easy to log in as root when running the test interactively.
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    users.extraUsers.root.initialHashedPassword = mkOverride 150 "";
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    services.xserver.displayManager.job.logToJournal = true;
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  };
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}
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