178 lines
4.4 KiB
Nix
178 lines
4.4 KiB
Nix
# Xen hypervisor (Dom0) support.
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{ config, pkgs, ... }:
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with pkgs.lib;
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let
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cfg = config.virtualisation.xen;
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xen = pkgs.xen;
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xendConfig = pkgs.writeText "xend-config.sxp"
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''
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(loglevel DEBUG)
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(network-script network-bridge)
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(vif-script vif-bridge)
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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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virtualisation.xen.enable =
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mkOption {
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default = false;
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description =
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''
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Setting this option enables the Xen hypervisor, a
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virtualisation technology that allows multiple virtual
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machines, known as <emphasis>domains</emphasis>, to run
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concurrently on the physical machine. NixOS runs as the
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privileged <emphasis>Domain 0</emphasis>. This option
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requires a reboot to take effect.
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'';
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};
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virtualisation.xen.bootParams =
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mkOption {
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default = "";
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description =
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''
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Parameters passed to the Xen hypervisor at boot time.
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'';
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};
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virtualisation.xen.domain0MemorySize =
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mkOption {
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default = 0;
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example = 512;
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description =
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''
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Amount of memory (in MiB) allocated to Domain 0 on boot.
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If set to 0, all memory is assigned to Domain 0.
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'';
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};
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};
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###### implementation
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config = mkIf cfg.enable {
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environment.systemPackages = [ xen ];
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# Domain 0 requires a pvops-enabled kernel.
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boot.kernelPackages = pkgs.linuxPackages_2_6_32_xen;
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boot.kernelModules =
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[ "xen_evtchn" "xen_gntdev" "xen_blkback" "xen_netback" "xen_pciback"
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"blktap" "tun"
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];
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# The radeonfb kernel module causes the screen to go black as soon
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# as it's loaded, so don't load it.
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boot.blacklistedKernelModules = [ "radeonfb" ];
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# Increase the number of loopback devices from the default (8),
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# which is way too small because every VM virtual disk requires a
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# loopback device.
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boot.extraModprobeConfig =
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''
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options loop max_loop=64
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'';
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virtualisation.xen.bootParams =
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[ "loglvl=all" "guest_loglvl=all" ] ++
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optional (cfg.domain0MemorySize != 0) "dom0_mem=${toString cfg.domain0MemorySize}M";
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system.extraSystemBuilderCmds =
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''
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ln -s ${xen}/boot/xen.gz $out/xen.gz
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echo "${toString cfg.bootParams}" > $out/xen-params
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'';
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# Mount the /proc/xen pseudo-filesystem.
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system.activationScripts.xen =
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''
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if [ -d /proc/xen ]; then
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${pkgs.sysvtools}/bin/mountpoint -q /proc/xen || \
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${pkgs.utillinux}/bin/mount -t xenfs none /proc/xen
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fi
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'';
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jobs.xend =
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{ description = "Xen control daemon";
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startOn = "stopped udevtrigger";
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path =
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[ pkgs.bridge_utils pkgs.gawk pkgs.iproute pkgs.nettools
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pkgs.utillinux pkgs.bash xen pkgs.pciutils pkgs.procps
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];
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environment.XENCONSOLED_TRACE = "hv";
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preStart =
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''
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mkdir -p /var/log/xen/console -m 0700
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${xen}/sbin/xend start
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# Wait until Xend is running.
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for ((i = 0; i < 60; i++)); do echo "waiting for xend..."; ${xen}/sbin/xend status && break; done
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${xen}/sbin/xend status || exit 1
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'';
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postStop = "${xen}/sbin/xend stop";
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};
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jobs.xendomains =
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{ description = "Automatically starts, saves and restores Xen domains on startup/shutdown";
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startOn = "started xend";
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stopOn = "starting shutdown and stopping xend";
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path = [ pkgs.xen ];
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environment.XENDOM_CONFIG = "${xen}/etc/sysconfig/xendomains";
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preStart =
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''
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mkdir -p /var/lock/subsys -m 755
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${xen}/etc/init.d/xendomains start
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'';
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postStop = "${xen}/etc/init.d/xendomains stop";
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};
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# To prevent a race between dhclient and xend's bridge setup
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# script (which renames eth* to peth* and recreates eth* as a
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# virtual device), start dhclient after xend.
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jobs.dhclient.startOn = mkOverride 50 "started xend";
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environment.etc =
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[ { source = xendConfig;
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target = "xen/xend-config.sxp";
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}
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{ source = "${xen}/etc/xen/scripts";
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target = "xen/scripts";
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}
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];
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# Xen provides udev rules.
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services.udev.packages = [ xen ];
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services.udev.path = [ pkgs.bridge_utils pkgs.iproute ];
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};
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}
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