nixpkgs/nixos/modules/virtualisation/xen-dom0.nix
Eelco Dolstra 29027fd1e1 Rewrite ‘with pkgs.lib’ -> ‘with lib’
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
2014-04-14 16:26:48 +02:00

180 lines
4.4 KiB
Nix

# Xen hypervisor (Dom0) support.
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.virtualisation.xen;
xen = pkgs.xen;
xendConfig = pkgs.writeText "xend-config.sxp"
''
(loglevel DEBUG)
(network-script network-bridge)
(vif-script vif-bridge)
'';
in
{
###### interface
options = {
virtualisation.xen.enable =
mkOption {
default = false;
description =
''
Setting this option enables the Xen hypervisor, a
virtualisation technology that allows multiple virtual
machines, known as <emphasis>domains</emphasis>, to run
concurrently on the physical machine. NixOS runs as the
privileged <emphasis>Domain 0</emphasis>. This option
requires a reboot to take effect.
'';
};
virtualisation.xen.bootParams =
mkOption {
default = "";
description =
''
Parameters passed to the Xen hypervisor at boot time.
'';
};
virtualisation.xen.domain0MemorySize =
mkOption {
default = 0;
example = 512;
description =
''
Amount of memory (in MiB) allocated to Domain 0 on boot.
If set to 0, all memory is assigned to Domain 0.
'';
};
};
###### implementation
config = mkIf cfg.enable {
environment.systemPackages = [ xen ];
# Domain 0 requires a pvops-enabled kernel.
boot.kernelPackages = pkgs.linuxPackages_3_2_xen;
boot.kernelModules =
[ "xen_evtchn" "xen_gntdev" "xen_blkback" "xen_netback" "xen_pciback"
"blktap" "tun"
];
# The radeonfb kernel module causes the screen to go black as soon
# as it's loaded, so don't load it.
boot.blacklistedKernelModules = [ "radeonfb" ];
# Increase the number of loopback devices from the default (8),
# which is way too small because every VM virtual disk requires a
# loopback device.
boot.extraModprobeConfig =
''
options loop max_loop=64
'';
virtualisation.xen.bootParams =
[ "loglvl=all" "guest_loglvl=all" ] ++
optional (cfg.domain0MemorySize != 0) "dom0_mem=${toString cfg.domain0MemorySize}M";
system.extraSystemBuilderCmds =
''
ln -s ${xen}/boot/xen.gz $out/xen.gz
echo "${toString cfg.bootParams}" > $out/xen-params
'';
# Mount the /proc/xen pseudo-filesystem.
system.activationScripts.xen =
''
if [ -d /proc/xen ]; then
${pkgs.sysvtools}/bin/mountpoint -q /proc/xen || \
${pkgs.utillinux}/bin/mount -t xenfs none /proc/xen
fi
'';
jobs.xend =
{ description = "Xen Control Daemon";
startOn = "stopped udevtrigger";
path =
[ pkgs.bridge_utils pkgs.gawk pkgs.iproute pkgs.nettools
pkgs.utillinux pkgs.bash xen pkgs.pciutils pkgs.procps
];
environment.XENCONSOLED_TRACE = "hv";
preStart =
''
mkdir -p /var/log/xen/console -m 0700
${xen}/sbin/xend start
# Wait until Xend is running.
for ((i = 0; i < 60; i++)); do echo "waiting for xend..."; ${xen}/sbin/xend status && break; done
${xen}/sbin/xend status || exit 1
'';
postStop = "${xen}/sbin/xend stop";
};
jobs.xendomains =
{ description = "Automatically starts, saves and restores Xen domains on startup/shutdown";
startOn = "started xend";
stopOn = "starting shutdown and stopping xend";
restartIfChanged = false;
path = [ pkgs.xen ];
environment.XENDOM_CONFIG = "${xen}/etc/sysconfig/xendomains";
preStart =
''
mkdir -p /var/lock/subsys -m 755
${xen}/etc/init.d/xendomains start
'';
postStop = "${xen}/etc/init.d/xendomains stop";
};
# To prevent a race between dhcpcd and xend's bridge setup script
# (which renames eth* to peth* and recreates eth* as a virtual
# device), start dhcpcd after xend.
jobs.dhcpcd.startOn = mkOverride 50 "started xend";
environment.etc =
[ { source = xendConfig;
target = "xen/xend-config.sxp";
}
{ source = "${xen}/etc/xen/scripts";
target = "xen/scripts";
}
];
# Xen provides udev rules.
services.udev.packages = [ xen ];
services.udev.path = [ pkgs.bridge_utils pkgs.iproute ];
};
}