Change:
# Xen hypervisor (Dom0) support. <del> { config, lib, pkgs, ... }: with lib; </del> <ins> { config, lib, pkgs, ... }: </ins> let cfg = config.virtualisation.xen; <ins> xenBootBuilder = pkgs.writeShellApplication { name = "xenBootBuilder"; runtimeInputs = (with pkgs; [ binutils coreutils findutils gawk gnugrep gnused jq ]) ++ lib.lists.optionals (cfg.efi.bootBuilderVerbosity == "info") ( with pkgs; [ bat diffutils ] ); runtimeEnv = { efiMountPoint = config.boot.loader.efi.efiSysMountPoint; }; text = builtins.readFile ./xen-boot-builder.sh; }; </ins> in { <del> imports = [ (mkRemovedOptionModule [ "virtualisation" "xen" "qemu" ] "You don't need this option anymore, it will work without it.") (mkRenamedOptionModule [ "virtualisation" "xen" "qemu-package" ] [ "virtualisation" "xen" "package-qemu" ]) </del> <ins> imports = with lib.modules; [ (mkRemovedOptionModule [ "virtualisation" "xen" "bridge" "name" ] "The Xen Network Bridge options are currently unavailable. Please set up your own bridge manually." ) (mkRemovedOptionModule [ "virtualisation" "xen" "bridge" "address" ] "The Xen Network Bridge options are currently unavailable. Please set up your own bridge manually." ) (mkRemovedOptionModule [ "virtualisation" "xen" "bridge" "prefixLength" ] "The Xen Network Bridge options are currently unavailable. Please set up your own bridge manually." ) (mkRemovedOptionModule [ "virtualisation" "xen" "bridge" "forwardDns" ] "The Xen Network Bridge options are currently unavailable. Please set up your own bridge manually." ) (mkRenamedOptionModule [ "virtualisation" "xen" "qemu-package" ] [ "virtualisation" "xen" "qemu" "package" ] ) (mkRenamedOptionModule [ "virtualisation" "xen" "package-qemu" ] [ "virtualisation" "xen" "qemu" "package" ] ) (mkRenamedOptionModule [ "virtualisation" "xen" "stored" ] [ "virtualisation" "xen" "store" "path" ] ) </ins> ]; <del> ###### interface </del> <ins> ## Interface ## </ins> <del> options = { </del> <ins> options.virtualisation.xen = { </ins> <del> virtualisation.xen.enable = mkOption { default = false; type = types.bool; description = '' Setting this option enables the Xen hypervisor, a virtualisation technology that allows multiple virtual machines, known as *domains*, to run concurrently on the physical machine.  NixOS runs as the privileged *Domain 0*.  This option requires a reboot to take effect. ''; }; </del> <ins> enable = lib.options.mkEnableOption "the Xen Hypervisor, a virtualisation technology defined as a *type-1 hypervisor*, which allows multiple virtual machines, known as *domains*, to run concurrently on the physical machine. NixOS runs as the privileged *Domain 0*. This option requires a reboot into a Xen kernel to take effect"; </ins> <del> virtualisation.xen.package = mkOption { type = types.package; defaultText = literalExpression "pkgs.xen"; example = literalExpression "pkgs.xen-light"; description = '' The package used for Xen binary. ''; relatedPackages = [ "xen" "xen-light" ]; </del> <ins> debug = lib.options.mkEnableOption "Xen debug features for Domain 0. This option enables some hidden debugging tests and features, and should not be used in production"; trace = lib.options.mkOption { type = lib.types.bool; default = cfg.debug; defaultText = lib.options.literalExpression "false"; example = true; description = "Whether to enable Xen debug tracing and logging for Domain 0."; </ins> }; <del> virtualisation.xen.package-qemu = mkOption { type = types.package; defaultText = literalExpression "pkgs.xen"; example = literalExpression "pkgs.qemu_xen-light"; </del> <ins> package = lib.options.mkOption { type = lib.types.package; default = pkgs.xen; defaultText = lib.options.literalExpression "pkgs.xen"; example = lib.options.literalExpression "pkgs.xen-slim"; </ins> description = '' <del> The package with qemu binaries for dom0 qemu and xendomains. </del> <ins> The package used for Xen Hypervisor. </ins> ''; <del> relatedPackages = [ "xen" { name = "qemu_xen-light"; comment = "For use with pkgs.xen-light."; } ]; </del> <ins> relatedPackages = [ "xen" "xen-slim" ]; </ins> }; <del> virtualisation.xen.bootParams = mkOption { default = []; type = types.listOf types.str; description = '' Parameters passed to the Xen hypervisor at boot time. ''; </del> <ins> qemu = { package = lib.options.mkOption { type = lib.types.package; default = pkgs.xen; defaultText = lib.options.literalExpression "pkgs.xen"; example = lib.options.literalExpression "pkgs.qemu_xen"; description = '' The package with QEMU binaries that runs in Domain 0 and virtualises the unprivileged domains. ''; relatedPackages = [ "xen" { name = "qemu_xen"; comment = "For use with `pkgs.xen-slim`."; } ]; </ins> }; <del> virtualisation.xen.domain0MemorySize = mkOption { default = 0; example = 512; type = types.addCheck types.int (n: n >= 0); description = '' Amount of memory (in MiB) allocated to Domain 0 on boot. If set to 0, all memory is assigned to Domain 0. ''; </del> <ins> pidFile = lib.options.mkOption { type = lib.types.path; default = "/run/xen/qemu-dom0.pid"; example = "/var/run/xen/qemu-dom0.pid"; description = "Path to the QEMU PID file."; </ins> }; <ins> }; </ins> <del> virtualisation.xen.bridge = { name = mkOption { default = "xenbr0"; type = types.str; description = '' Name of bridge the Xen domUs connect to. ''; }; </del> <ins> bootParams = lib.options.mkOption { default = [ ]; example = '' [ "iommu=force:true,qinval:true,debug:true" "noreboot=true" "vga=ask" ] ''; type = lib.types.listOf lib.types.str; description = '' Xen Command Line parameters passed to Domain 0 at boot time. Note: these are different from `boot.kernelParams`. See the [Xen documentation](https://xenbits.xenproject.org/docs/unstable/misc/xen-command-line.html) for more information. ''; }; </ins> <del> address = mkOption { type = types.str; default = "172.16.0.1"; description = '' IPv4 address of the bridge. ''; }; </del> <ins> efi = { bootBuilderVerbosity = lib.options.mkOption { type = lib.types.enum [ "default" "info" "debug" "quiet" ]; default = "default"; example = "info"; description = '' The EFI boot entry builder script should be called with exactly one of the following arguments in order to specify its verbosity: </ins> <del> prefixLength = mkOption { type = types.addCheck types.int (n: n >= 0 && n <= 32); default = 16; description = '' Subnet mask of the bridge interface, specified as the number of bits in the prefix (`24`). A DHCP server will provide IP addresses for the whole, remaining subnet. ''; }; </del> <ins> - `quiet` supresses all messages. </ins> <del> forwardDns = mkOption { type = types.bool; default = false; description = '' If set to `true`, the DNS queries from the hosts connected to the bridge will be forwarded to the DNS servers specified in /etc/resolv.conf . ''; }; </del> <ins> - `default` adds a simple "Installing Xen Hypervisor boot entries...done." message to the script. </ins> <del> }; </del> <ins> - `info` is the same as `default`, but it also prints a diff with information on which generations were altered. - This option adds two extra dependencies to the script: `diffutils` and `bat`. </ins> <del> virtualisation.xen.stored = mkOption { type = types.path; description = '' Xen Store daemon to use. Defaults to oxenstored of the xen package. ''; </del> <ins> - `debug` prints information messages for every single step of the script. This option does not alter the actual functionality of the script, just the number of messages printed when rebuilding the system. ''; </ins> }; <del> virtualisation.xen.domains = { extraConfig = mkOption { type = types.lines; default = ""; description = '' Options defined here will override the defaults for xendomains. The default options can be seen in the file included from /etc/default/xendomains. ''; }; </del> <ins> path = lib.options.mkOption { type = lib.types.path; default = "${cfg.package.boot}/${cfg.package.efi}"; defaultText = lib.options.literalExpression "${config.virtualisation.xen.package.boot}/${config.virtualisation.xen.package.efi}"; example = lib.options.literalExpression "${config.virtualisation.xen.package}/boot/efi/efi/nixos/xen-${config.virtualisation.xen.package.version}.efi"; description = '' Path to xen.efi. `pkgs.xen` is patched to install the xen.efi file on `$boot/boot/xen.efi`, but an unpatched Xen build may install it somewhere else, such as `$out/boot/efi/efi/nixos/xen.efi`. Unless you're building your own Xen derivation, you should leave this option as the default value. ''; </ins> }; <ins> }; </ins> <del> virtualisation.xen.trace = mkEnableOption "Xen tracing"; </del> <ins> dom0Resources = { maxVCPUs = lib.options.mkOption { default = 0; example = 4; type = lib.types.ints.unsigned; description = '' Amount of virtual CPU cores allocated to Domain 0 on boot. If set to 0, all cores are assigned to Domain 0, and unprivileged domains will compete with Domain 0 for CPU time. ''; }; </ins> <del> }; </del> <ins> memory = lib.options.mkOption { default = 0; example = 512; type = lib.types.ints.unsigned; description = '' Amount of memory (in MiB) allocated to Domain 0 on boot. If set to 0, all memory is assigned to Domain 0, and unprivileged domains will compete with Domain 0 for free RAM. ''; }; maxMemory = lib.options.mkOption { default = cfg.dom0Resources.memory; defaultText = lib.options.literalExpression "config.virtualisation.xen.dom0Resources.memory"; example = 1024; type = lib.types.ints.unsigned; description = '' Maximum amount of memory (in MiB) that Domain 0 can dynamically allocate to itself. Does nothing if set to the same amount as virtualisation.xen.memory, or if that option is set to 0. ''; }; }; </ins> <del> ###### implementation </del> <ins> domains = { extraConfig = lib.options.mkOption { type = lib.types.lines; default = ""; example = '' XENDOMAINS_SAVE=/persist/xen/save XENDOMAINS_RESTORE=false XENDOMAINS_CREATE_USLEEP=10000000 ''; description = '' Options defined here will override the defaults for xendomains. The default options can be seen in the file included from /etc/default/xendomains. ''; }; }; </ins> <del> config = mkIf cfg.enable { assertions = [ { assertion = pkgs.stdenv.isx86_64; message = "Xen currently not supported on ${pkgs.stdenv.hostPlatform.system}"; } { assertion = config.boot.loader.grub.enable && (config.boot.loader.grub.efiSupport == false); message = "Xen currently does not support EFI boot"; } ]; </del> <ins> store = { path = lib.options.mkOption { type = lib.types.path; default = "${cfg.package}/bin/oxenstored"; defaultText = lib.options.literalExpression "${config.virtualisation.xen.package}/bin/oxenstored"; example = lib.options.literalExpression "${config.virtualisation.xen.package}/bin/xenstored"; description = '' Path to the Xen Store Daemon. This option is useful to switch between the legacy C-based Xen Store Daemon, and the newer OCaml-based Xen Store Daemon, `oxenstored`. ''; }; type = lib.options.mkOption { type = lib.types.enum [ "c" "ocaml" ]; default = if (lib.strings.hasSuffix "oxenstored" cfg.store.path) then "ocaml" else "c"; internal = true; readOnly = true; description = "Helper internal option that determines the type of the Xen Store Daemon based on cfg.store.path."; }; settings = lib.options.mkOption { default = { }; example = { enableMerge = false; quota.maxWatchEvents = 2048; quota.enable = true; conflict.maxHistorySeconds = 0.12; conflict.burstLimit = 15.0; xenstored.log.file = "/dev/null"; xenstored.log.level = "info"; }; description = '' The OCaml-based Xen Store Daemon configuration. This option does nothing with the C-based `xenstored`. ''; type = lib.types.submodule { options = { pidFile = lib.options.mkOption { default = "/run/xen/xenstored.pid"; example = "/var/run/xen/xenstored.pid"; type = lib.types.path; description = "Path to the Xen Store Daemon PID file."; }; testEAGAIN = lib.options.mkOption { default = cfg.debug; defaultText = lib.options.literalExpression "config.virtualisation.xen.debug"; example = true; type = lib.types.bool; visible = false; description = "Randomly fail a transaction with EAGAIN. This option is used for debugging purposes only."; }; enableMerge = lib.options.mkOption { default = true; example = false; type = lib.types.bool; description = "Whether to enable transaction merge support."; }; conflict = { burstLimit = lib.options.mkOption { default = 5.0; example = 15.0; type = lib.types.addCheck ( lib.types.float // { name = "nonnegativeFloat"; description = "nonnegative floating point number, meaning >=0"; descriptionClass = "nonRestrictiveClause"; } ) (n: n >= 0); description = '' Limits applied to domains whose writes cause other domains' transaction commits to fail. Must include decimal point. The burst limit is the number of conflicts a domain can cause to fail in a short period; this value is used for both the initial and the maximum value of each domain's conflict-credit, which falls by one point for each conflict caused, and when it reaches zero the domain's requests are ignored. ''; }; maxHistorySeconds = lib.options.mkOption { default = 5.0e-2; example = 1.0; type = lib.types.addCheck ( lib.types.float // { description = "nonnegative floating point number, meaning >=0"; } ) (n: n >= 0); description = '' Limits applied to domains whose writes cause other domains' transaction commits to fail. Must include decimal point. The conflict-credit is replenished over time: one point is issued after each conflict.maxHistorySeconds, so this is the minimum pause-time during which a domain will be ignored. ''; }; rateLimitIsAggregate = lib.options.mkOption { default = true; example = false; type = lib.types.bool; description = '' If the conflict.rateLimitIsAggregate option is `true`, then after each tick one point of conflict-credit is given to just one domain: the one at the front of the queue. If `false`, then after each tick each domain gets a point of conflict-credit. In environments where it is known that every transaction will involve a set of nodes that is writable by at most one other domain, then it is safe to set this aggregate limit flag to `false` for better performance. (This can be determined by considering the layout of the xenstore tree and permissions, together with the content of the transactions that require protection.) A transaction which involves a set of nodes which can be modified by multiple other domains can suffer conflicts caused by any of those domains, so the flag must be set to `true`. ''; }; }; perms = { enable = lib.options.mkOption { default = true; example = false; type = lib.types.bool; description = "Whether to enable the node permission system."; }; enableWatch = lib.options.mkOption { default = true; example = false; type = lib.types.bool; description = '' Whether to enable the watch permission system. When this is set to `true`, unprivileged guests can only get watch events for xenstore entries that they would've been able to read. When this is set to `false`, unprivileged guests may get watch events for xenstore entries that they cannot read. The watch event contains only the entry name, not the value. This restores behaviour prior to [XSA-115](https://xenbits.xenproject.org/xsa/advisory-115.html). ''; }; }; quota = { enable = lib.options.mkOption { default = true; example = false; type = lib.types.bool; description = "Whether to enable the quota system."; }; maxEntity = lib.options.mkOption { default = 1000; example = 1024; type = lib.types.ints.positive; description = "Entity limit for transactions."; }; maxSize = lib.options.mkOption { default = 2048; example = 4096; type = lib.types.ints.positive; description = "Size limit for transactions."; }; maxWatch = lib.options.mkOption { default = 100; example = 256; type = lib.types.ints.positive; description = "Maximum number of watches by the Xenstore Watchdog."; }; transaction = lib.options.mkOption { default = 10; example = 50; type = lib.types.ints.positive; description = "Maximum number of transactions."; }; maxRequests = lib.options.mkOption { default = 1024; example = 1024; type = lib.types.ints.positive; description = "Maximum number of requests per transaction."; }; maxPath = lib.options.mkOption { default = 1024; example = 1024; type = lib.types.ints.positive; description = "Path limit for the quota system."; }; maxOutstanding = lib.options.mkOption { default = 1024; example = 1024; type = lib.types.ints.positive; description = "Maximum outstanding requests, i.e. in-flight requests / domain."; }; maxWatchEvents = lib.options.mkOption { default = 1024; example = 2048; type = lib.types.ints.positive; description = "Maximum number of outstanding watch events per watch."; }; }; persistent = lib.options.mkOption { default = false; example = true; type = lib.types.bool; description = "Whether to activate the filed base backend."; }; xenstored = { log = { file = lib.options.mkOption { default = "/var/log/xen/xenstored.log"; example = "/dev/null"; type = lib.types.path; description = "Path to the Xen Store log file."; }; level = lib.options.mkOption { default = if cfg.trace then "debug" else null; defaultText = lib.options.literalExpression "if (config.virtualisation.xen.trace == true) then "debug" else null"; example = "error"; type = lib.types.nullOr ( lib.types.enum [ "debug" "info" "warn" "error" ] ); description = "Logging level for the Xen Store."; }; # The hidden options below have no upstream documentation whatsoever. # The nb* options appear to alter the log rotation behaviour, and # the specialOps option appears to affect the Xenbus logging logic. nbFiles = lib.options.mkOption { default = 10; example = 16; type = lib.types.int; visible = false; description = "Set `xenstored-log-nb-files`."; }; }; accessLog = { file = lib.options.mkOption { default = "/var/log/xen/xenstored-access.log"; example = "/var/log/security/xenstored-access.log"; type = lib.types.path; description = "Path to the Xen Store access log file."; }; nbLines = lib.options.mkOption { default = 13215; example = 16384; type = lib.types.int; visible = false; description = "Set `access-log-nb-lines`."; }; nbChars = lib.options.mkOption { default = 180; example = 256; type = lib.types.int; visible = false; description = "Set `acesss-log-nb-chars`."; }; specialOps = lib.options.mkOption { default = false; example = true; type = lib.types.bool; visible = false; description = "Set `access-log-special-ops`."; }; }; xenfs = { kva = lib.options.mkOption { default = "/proc/xen/xsd_kva"; example = cfg.store.settings.xenstored.xenfs.kva; type = lib.types.path; visible = false; description = '' Path to the Xen Store Daemon KVA location inside the XenFS pseudo-filesystem. While it is possible to alter this value, some drivers may be hardcoded to follow the default paths. ''; }; port = lib.options.mkOption { default = "/proc/xen/xsd_port"; example = cfg.store.settings.xenstored.xenfs.port; type = lib.types.path; visible = false; description = '' Path to the Xen Store Daemon userspace port inside the XenFS pseudo-filesystem. While it is possible to alter this value, some drivers may be hardcoded to follow the default paths. ''; }; }; }; ringScanInterval = lib.options.mkOption { default = 20; example = 30; type = lib.types.addCheck ( lib.types.int // { name = "nonzeroInt"; description = "nonzero signed integer, meaning !=0"; descriptionClass = "nonRestrictiveClause"; } ) (n: n != 0); description = '' Perodic scanning for all the rings as a safenet for lazy clients. Define the interval in seconds; set to a negative integer to disable. ''; }; }; }; }; }; }; </ins> <del> virtualisation.xen.package = mkDefault pkgs.xen; virtualisation.xen.package-qemu = mkDefault pkgs.xen; virtualisation.xen.stored = mkDefault "${cfg.package}/bin/oxenstored"; </del> <ins> ## Implementation ## </ins> <del> environment.systemPackages = [ cfg.package ]; </del> <ins> config = lib.modules.mkIf cfg.enable { assertions = [ { assertion = pkgs.stdenv.isx86_64; message = "Xen is currently not supported on ${pkgs.stdenv.hostPlatform.system}."; } { assertion = config.boot.loader.systemd-boot.enable || (config.boot ? lanzaboote) && config.boot.lanzaboote.enable; message = "Xen only supports booting on systemd-boot or Lanzaboote."; } { assertion = config.boot.initrd.systemd.enable; message = "Xen does not support the legacy script-based Stage 1 initrd."; } { assertion = cfg.dom0Resources.maxMemory >= cfg.dom0Resources.memory; message = '' You have allocated more memory to dom0 than virtualisation.xen.dom0Resources.maxMemory allows for. Please increase the maximum memory limit, or decrease the default memory allocation. ''; } { assertion = cfg.debug -> cfg.trace; message = "Xen's debugging features are enabled, but logging is disabled. This is most likely not what you want."; } { assertion = cfg.store.settings.quota.maxWatchEvents >= cfg.store.settings.quota.maxOutstanding; message = '' Upstream Xen recommends that maxWatchEvents be equal to or greater than maxOutstanding, in order to mitigate denial of service attacks from malicious frontends. ''; } ]; </ins> <del> boot.kernelModules = [ "xen-evtchn" "xen-gntdev" "xen-gntalloc" "xen-blkback" "xen-netback" "xen-pciback" "evtchn" "gntdev" "netbk" "blkbk" "xen-scsibk" "usbbk" "pciback" "xen-acpi-processor" "blktap2" "tun" "netxen_nic" "xen_wdt" "xen-acpi-processor" "xen-privcmd" "xen-scsiback" </del> <ins> virtualisation.xen.bootParams = lib.lists.optionals cfg.trace [ "loglvl=all" "guest_loglvl=all" ] ++ lib.lists.optional (cfg.dom0Resources.memory != 0) "dom0_mem=${toString cfg.dom0Resources.memory}M${ lib.strings.optionalString ( cfg.dom0Resources.memory != cfg.dom0Resources.maxMemory ) ",max:${toString cfg.dom0Resources.maxMemory}M" }" ++ lib.lists.optional ( cfg.dom0Resources.maxVCPUs != 0 ) "dom0_max_vcpus=${toString cfg.dom0Resources.maxVCPUs}"; boot = { kernelModules = [ "xen-evtchn" "xen-gntdev" "xen-gntalloc" "xen-blkback" "xen-netback" "xen-pciback" "evtchn" "gntdev" "netbk" "blkbk" "xen-scsibk" "usbbk" "pciback" "xen-acpi-processor" "blktap2" "tun" "netxen_nic" "xen_wdt" "xen-acpi-processor" "xen-privcmd" "xen-scsiback" </ins> "xenfs" ]; <del> # The xenfs module is needed in system.activationScripts.xen, but # the modprobe command there fails silently. Include xenfs in the # initrd as a work around. boot.initrd.kernelModules = [ "xenfs" ]; # The radeonfb kernel module causes the screen to go black as soon # as it's loaded, so don't load it. boot.blacklistedKernelModules = [ "radeonfb" ]; </del> <ins> # The xenfs module is needed to mount /proc/xen. initrd.kernelModules = [ "xenfs" ]; </ins> <del> # Increase the number of loopback devices from the default (8), # which is way too small because every VM virtual disk requires a # loopback device. boot.extraModprobeConfig = '' </del> <ins> # Increase the number of loopback devices from the default (8), # which is way too small because every VM virtual disk requires a # loopback device. extraModprobeConfig = '' </ins> options loop max_loop=64 ''; <del> virtualisation.xen.bootParams = [] ++ optionals cfg.trace [ "loglvl=all" "guest_loglvl=all" ] ++ optional (cfg.domain0MemorySize != 0) "dom0_mem=${toString cfg.domain0MemorySize}M"; system.extraSystemBuilderCmds = '' ln -s ${cfg.package}/boot/xen.gz $out/xen.gz echo "${toString cfg.bootParams}" > $out/xen-params ''; </del> <ins> # Xen Bootspec extension. This extension allows NixOS bootloaders to # fetch the `xen.efi` path and access the `cfg.bootParams` option. bootspec.extensions = { "org.xenproject.bootspec.v1" = { xen = cfg.efi.path; xenParams = cfg.bootParams; }; }; </ins> <del> # Mount the /proc/xen pseudo-filesystem. system.activationScripts.xen = '' if [ -d /proc/xen ]; then ${pkgs.kmod}/bin/modprobe xenfs 2> /dev/null ${pkgs.util-linux}/bin/mountpoint -q /proc/xen ||  ${pkgs.util-linux}/bin/mount -t xenfs none /proc/xen fi </del> <ins> # See the `xenBootBuilder` script in the main `let...in` statement of this file. loader.systemd-boot.extraInstallCommands = '' ${lib.meta.getExe xenBootBuilder} ${cfg.efi.bootBuilderVerbosity} </ins> ''; <ins> }; </ins> # Domain 0 requires a pvops-enabled kernel. <del> system.requiredKernelConfig = with config.lib.kernelConfig; [ (isYes "XEN") (isYes "X86_IO_APIC") (isYes "ACPI") (isYes "XEN_DOM0") (isYes "PCI_XEN") (isYes "XEN_DEV_EVTCHN") (isYes "XENFS") (isYes "XEN_COMPAT_XENFS") (isYes "XEN_SYS_HYPERVISOR") (isYes "XEN_GNTDEV") (isYes "XEN_BACKEND") (isModule "XEN_NETDEV_BACKEND") (isModule "XEN_BLKDEV_BACKEND") (isModule "XEN_PCIDEV_BACKEND") (isYes "XEN_BALLOON") (isYes "XEN_SCRUB_PAGES") </del> <ins> # All NixOS kernels come with this enabled by default; this is merely a sanity check. system.requiredKernelConfig = with config.lib.kernelConfig; [ (isYes "XEN") (isYes "X86_IO_APIC") (isYes "ACPI") (isYes "XEN_DOM0") (isYes "PCI_XEN") (isYes "XEN_DEV_EVTCHN") (isYes "XENFS") (isYes "XEN_COMPAT_XENFS") (isYes "XEN_SYS_HYPERVISOR") (isYes "XEN_GNTDEV") (isYes "XEN_BACKEND") (isModule "XEN_NETDEV_BACKEND") (isModule "XEN_BLKDEV_BACKEND") (isModule "XEN_PCIDEV_BACKEND") (isYes "XEN_BALLOON") (isYes "XEN_SCRUB_PAGES") ]; environment = { systemPackages = [ cfg.package cfg.qemu.package </ins> ]; <ins> etc = # Set up Xen Domain 0 configuration files. { "xen/xl.conf".source = "${cfg.package}/etc/xen/xl.conf"; # TODO: Add options to configure xl.conf declaratively. It's worth considering making a new "xl value" type, as it could be reused to produce xl.cfg (domain definition) files. "xen/scripts-xen" = { source = "${cfg.package}/etc/xen/scripts/*"; target = "xen/scripts"; }; "default/xencommons".text = '' source ${cfg.package}/etc/default/xencommons XENSTORED="${cfg.store.path}" QEMU_XEN="${cfg.qemu.package}/${cfg.qemu.package.qemu-system-i386}" ${lib.strings.optionalString cfg.trace '' XENSTORED_TRACE=yes XENCONSOLED_TRACE=all ''} ''; "default/xendomains".text = '' source ${cfg.package}/etc/default/xendomains </ins> <del> environment.etc = { "xen/xl.conf".source = "${cfg.package}/etc/xen/xl.conf"; "xen/scripts".source = "${cfg.package}/etc/xen/scripts"; "default/xendomains".text = '' source ${cfg.package}/etc/default/xendomains ${cfg.domains.extraConfig} ''; } // optionalAttrs (builtins.compareVersions cfg.package.version "4.10" >= 0) { # in V 4.10 oxenstored requires /etc/xen/oxenstored.conf to start "xen/oxenstored.conf".source = "${cfg.package}/etc/xen/oxenstored.conf"; }; </del> <ins> ${cfg.domains.extraConfig} ''; } # The OCaml-based Xen Store Daemon requires /etc/xen/oxenstored.conf to start. // lib.attrsets.optionalAttrs (cfg.store.type == "ocaml") { "xen/oxenstored.conf".text = '' pid-file = ${cfg.store.settings.pidFile} test-eagain = ${lib.trivial.boolToString cfg.store.settings.testEAGAIN} merge-activate = ${toString cfg.store.settings.enableMerge} conflict-burst-limit = ${toString cfg.store.settings.conflict.burstLimit} conflict-max-history-seconds = ${toString cfg.store.settings.conflict.maxHistorySeconds} conflict-rate-limit-is-aggregate = ${toString cfg.store.settings.conflict.rateLimitIsAggregate} perms-activate = ${toString cfg.store.settings.perms.enable} perms-watch-activate = ${toString cfg.store.settings.perms.enableWatch} quota-activate = ${toString cfg.store.settings.quota.enable} quota-maxentity = ${toString cfg.store.settings.quota.maxEntity} quota-maxsize = ${toString cfg.store.settings.quota.maxSize} quota-maxwatch = ${toString cfg.store.settings.quota.maxWatch} quota-transaction = ${toString cfg.store.settings.quota.transaction} quota-maxrequests = ${toString cfg.store.settings.quota.maxRequests} quota-path-max = ${toString cfg.store.settings.quota.maxPath} quota-maxoutstanding = ${toString cfg.store.settings.quota.maxOutstanding} quota-maxwatchevents = ${toString cfg.store.settings.quota.maxWatchEvents} persistent = ${lib.trivial.boolToString cfg.store.settings.persistent} xenstored-log-file = ${cfg.store.settings.xenstored.log.file} xenstored-log-level = ${ if isNull cfg.store.settings.xenstored.log.level then "null" else cfg.store.settings.xenstored.log.level } xenstored-log-nb-files = ${toString cfg.store.settings.xenstored.log.nbFiles} access-log-file = ${cfg.store.settings.xenstored.accessLog.file} access-log-nb-lines = ${toString cfg.store.settings.xenstored.accessLog.nbLines} acesss-log-nb-chars = ${toString cfg.store.settings.xenstored.accessLog.nbChars} access-log-special-ops = ${lib.trivial.boolToString cfg.store.settings.xenstored.accessLog.specialOps} ring-scan-interval = ${toString cfg.store.settings.ringScanInterval} xenstored-kva = ${cfg.store.settings.xenstored.xenfs.kva} xenstored-port = ${cfg.store.settings.xenstored.xenfs.port} ''; }; }; </ins> # Xen provides udev rules. services.udev.packages = [ cfg.package ]; <del> services.udev.path = [ pkgs.bridge-utils pkgs.iproute2 ]; systemd.services.xen-store = { description = "Xen Store Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "network.target" "xen-store.socket" ]; requires = [ "xen-store.socket" ]; preStart = '' export XENSTORED_ROOTDIR="/var/lib/xenstored" rm -f "$XENSTORED_ROOTDIR"/tdb* &>/dev/null mkdir -p /var/run mkdir -p /var/log/xen # Running xl requires /var/log/xen and /var/lib/xen, mkdir -p /var/lib/xen # so we create them here unconditionally. grep -q control_d /proc/xen/capabilities ''; serviceConfig = if (builtins.compareVersions cfg.package.version "4.8" < 0) then { ExecStart = '' ${cfg.stored}${optionalString cfg.trace " -T /var/log/xen/xenstored-trace.log"} --no-fork ''; } else { ExecStart = '' ${cfg.package}/etc/xen/scripts/launch-xenstore ''; Type            = "notify"; RemainAfterExit = true; NotifyAccess    = "all"; }; postStart = '' ${optionalString (builtins.compareVersions cfg.package.version "4.8" < 0) '' time=0 timeout=30 # Wait for xenstored to actually come up, timing out after 30 seconds while [ $time -lt $timeout ] && ! `${cfg.package}/bin/xenstore-read -s / >/dev/null 2>&1` ; do time=$(($time+1)) sleep 1 done # Exit if we timed out if ! [ $time -lt $timeout ] ; then echo "Could not start Xenstore Daemon" exit 1 fi ''} echo "executing xen-init-dom0" ${cfg.package}/lib/xen/bin/xen-init-dom0 ''; }; </del> <ins> systemd = { # Xen provides systemd units. packages = [ cfg.package ]; mounts = [ { description = "Mount /proc/xen files"; what = "xenfs"; where = "/proc/xen"; type = "xenfs"; unitConfig = { ConditionPathExists = "/proc/xen"; RefuseManualStop = "true"; }; } ]; </ins> <del> systemd.sockets.xen-store = { description = "XenStore Socket for userspace API"; wantedBy = [ "sockets.target" ]; socketConfig = { ListenStream = [ "/var/run/xenstored/socket" "/var/run/xenstored/socket_ro" ]; SocketMode = "0660"; SocketUser = "root"; SocketGroup = "root"; }; }; </del> <ins> services = { # While this service is installed by the `xen` package, it shouldn't be used in dom0. xendriverdomain.enable = false; </ins> <del> systemd.services.xen-console = { description = "Xen Console Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "xen-store.service" ]; requires = [ "xen-store.service" ]; preStart = '' mkdir -p /var/run/xen ${optionalString cfg.trace "mkdir -p /var/log/xen"} grep -q control_d /proc/xen/capabilities ''; serviceConfig = { ExecStart = '' ${cfg.package}/bin/xenconsoled ${optionalString ((builtins.compareVersions cfg.package.version "4.8" >= 0)) " -i"} ${optionalString cfg.trace " --log=all --log-dir=/var/log/xen"} </del> <ins> xenstored = { wantedBy = [ "multi-user.target" ]; preStart = '' export XENSTORED_ROOTDIR="/var/lib/xenstored" rm -f "$XENSTORED_ROOTDIR"/tdb* &>/dev/null mkdir -p /var/{run,log,lib}/xen </ins> ''; <del> }; }; systemd.services.xen-qemu = { description = "Xen Qemu Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "xen-console.service" ]; requires = [ "xen-store.service" ]; serviceConfig.ExecStart = '' ${cfg.package-qemu}/${cfg.package-qemu.qemu-system-i386}  -xen-attach -xen-domid 0 -name dom0 -M xenpv  -nographic -monitor /dev/null -serial /dev/null -parallel /dev/null ''; }; </del> <ins> }; xen-init-dom0 = { restartIfChanged = false; wantedBy = [ "multi-user.target" ]; }; </ins> <del> systemd.services.xen-watchdog = { description = "Xen Watchdog Daemon"; wantedBy = [ "multi-user.target" ]; after = [ "xen-qemu.service" "xen-domains.service" ]; serviceConfig.ExecStart = "${cfg.package}/bin/xenwatchdogd 30 15"; serviceConfig.Type = "forking"; serviceConfig.RestartSec = "1"; serviceConfig.Restart = "on-failure"; }; </del> <ins> xen-qemu-dom0-disk-backend = { wantedBy = [ "multi-user.target" ]; serviceConfig = { PIDFile = cfg.qemu.pidFile; ExecStart = '' ${cfg.qemu.package}/${cfg.qemu.package.qemu-system-i386}  -xen-domid 0 -xen-attach -name dom0 -nographic -M xenpv  -daemonize -monitor /dev/null -serial /dev/null -parallel  /dev/null -nodefaults -no-user-config -pidfile  ${cfg.qemu.pidFile} ''; }; }; xenconsoled.wantedBy = [ "multi-user.target" ]; </ins> <del> systemd.services.xen-bridge = { description = "Xen bridge"; wantedBy = [ "multi-user.target" ]; before = [ "xen-domains.service" ]; preStart = '' mkdir -p /var/run/xen touch /var/run/xen/dnsmasq.pid touch /var/run/xen/dnsmasq.etherfile touch /var/run/xen/dnsmasq.leasefile IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Usable range` export XEN_BRIDGE_IP_RANGE_START="${"${data[1]//[[:blank:]]/}"}" export XEN_BRIDGE_IP_RANGE_END="${"${data[2]//[[:blank:]]/}"}" IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Network address` export XEN_BRIDGE_NETWORK_ADDRESS="${"${data[1]//[[:blank:]]/}"}" IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Network mask` export XEN_BRIDGE_NETMASK="${"${data[1]//[[:blank:]]/}"}" echo "${cfg.bridge.address} host gw dns" > /var/run/xen/dnsmasq.hostsfile cat <<EOF > /var/run/xen/dnsmasq.conf no-daemon pid-file=/var/run/xen/dnsmasq.pid interface=${cfg.bridge.name} except-interface=lo bind-interfaces auth-zone=xen.local,$XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} domain=xen.local addn-hosts=/var/run/xen/dnsmasq.hostsfile expand-hosts strict-order no-hosts bogus-priv ${optionalString (!cfg.bridge.forwardDns) '' no-resolv no-poll auth-server=dns.xen.local,${cfg.bridge.name} ''} filterwin2k clear-on-reload domain-needed dhcp-hostsfile=/var/run/xen/dnsmasq.etherfile dhcp-authoritative dhcp-range=$XEN_BRIDGE_IP_RANGE_START,$XEN_BRIDGE_IP_RANGE_END dhcp-no-override no-ping dhcp-leasefile=/var/run/xen/dnsmasq.leasefile EOF # DHCP ${pkgs.iptables}/bin/iptables -w -I INPUT  -i ${cfg.bridge.name} -p tcp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT ${pkgs.iptables}/bin/iptables -w -I INPUT  -i ${cfg.bridge.name} -p udp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT # DNS ${pkgs.iptables}/bin/iptables -w -I INPUT  -i ${cfg.bridge.name} -p tcp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT ${pkgs.iptables}/bin/iptables -w -I INPUT  -i ${cfg.bridge.name} -p udp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT ${pkgs.bridge-utils}/bin/brctl addbr ${cfg.bridge.name} ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} ${cfg.bridge.address} ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} netmask $XEN_BRIDGE_NETMASK ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} up ''; serviceConfig.ExecStart = "${pkgs.dnsmasq}/bin/dnsmasq --conf-file=/var/run/xen/dnsmasq.conf"; postStop = '' IFS='-' read -a data <<< `${pkgs.sipcalc}/bin/sipcalc ${cfg.bridge.address}/${toString cfg.bridge.prefixLength} | grep Network address` export XEN_BRIDGE_NETWORK_ADDRESS="${"${data[1]//[[:blank:]]/}"}" ${pkgs.inetutils}/bin/ifconfig ${cfg.bridge.name} down ${pkgs.bridge-utils}/bin/brctl delbr ${cfg.bridge.name} # DNS ${pkgs.iptables}/bin/iptables -w -D INPUT  -i ${cfg.bridge.name} -p udp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT ${pkgs.iptables}/bin/iptables -w -D INPUT  -i ${cfg.bridge.name} -p tcp -d ${cfg.bridge.address} --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT # DHCP ${pkgs.iptables}/bin/iptables -w -D INPUT  -i ${cfg.bridge.name} -p udp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT ${pkgs.iptables}/bin/iptables -w -D INPUT  -i ${cfg.bridge.name} -p tcp -s $XEN_BRIDGE_NETWORK_ADDRESS/${toString cfg.bridge.prefixLength} --sport 68 --dport 67 -j ACCEPT ''; }; </del> <ins> xen-watchdog = { wantedBy = [ "multi-user.target" ]; serviceConfig = { RestartSec = "1"; Restart = "on-failure"; }; }; </ins> <del> systemd.services.xen-domains = { description = "Xen domains - automatically starts, saves and restores Xen domains"; wantedBy = [ "multi-user.target" ]; after = [ "xen-bridge.service" "xen-qemu.service" ]; requires = [ "xen-bridge.service" "xen-qemu.service" ]; ## 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. before = [ "dhcpd.service" ]; restartIfChanged = false; serviceConfig.RemainAfterExit = "yes"; path = [ cfg.package cfg.package-qemu ]; environment.XENDOM_CONFIG = "${cfg.package}/etc/sysconfig/xendomains"; preStart = "mkdir -p /var/lock/subsys -m 755"; serviceConfig.ExecStart = "${cfg.package}/etc/init.d/xendomains start"; serviceConfig.ExecStop = "${cfg.package}/etc/init.d/xendomains stop"; </del> <ins> xendomains = { restartIfChanged = false; path = [ cfg.package cfg.qemu.package ]; preStart = "mkdir -p /var/lock/subsys -m 755"; wantedBy = [ "multi-user.target" ]; }; }; </ins> }; }; <ins> meta.maintainers = with lib.maintainers; [ sigmasquadron ]; </ins> }

Discussion:
I am unable to get xen working on my system following the advise from with and without: the system and expect failure to boot due to the kernel panic in domain0 (?) Please run and paste the result. !
CC
I haven't been using Xen for a while now so I have no idea if it's broken now. But AFAIK you can't use both Xen and KVM together, so your config shouldn't work in any case.
I marked this as stale due to inactivity. &rarr;

Describe the bug Xen package does not build on EFI systems even while support was in Add support for booting as Xen dom0 on EFI systems. To Reproduce Enable Xen in on a system with EFI boot: Expected behavior Xen packages are built and enabled. Log Error message is given to the user as nix configuration fails to build. Related to , failed assertion. Notify maintainers <!-- Please @ people who are in the list of the offending package or module. If in doubt, check for whoever last touched something. --Xen maintainers Metadata Using with EFI boot Maintainer information:
I marked this as stale due to inactivity. &rarr;
Shouldn't this just work since ?
I'm interested in this working. Is anyone working on it? Can I help in some way?
i looked into this couple of months ago and it looked to me like it just didnt work because of assertions left over before xen supported efi but im not knowledgeable enough on the subject to confirm if that is the only thing needed to fix
I have removed the assertion, but I cannot activate. There is a bug where if you are running on a non-Xen system, enable Xen, and attempt to activate, you get an error because Xen-stored (or something) service cannot read . If one ignores this, and reboots, at boot time, there is an error due to "xenfs" kmod not loading. I find that my currently booted system has a "" in but it fails to insert. It depends on which is also there and which also fails to load. I am currently nixing (is that a verb?) on I cloned today (in order to fix the EFI assertion) so perhaps that is an issue. I will see if I can checkout the 23.05 commit, but don't expect much luck there. Xen seems to be pretty much dead, which is sad. Yes, i know Qubes-OS uses it. And boots with UEFI with no problems, FWIW, here is an of an attempt to load the : Nothing to .
maybe add both to availableKernelModules and nixos-rebuild boot?
Had those set. No difference.

On reflection, given that what I have so far does not appear to boot first, I suspect the kmods fail to load because they reject being loaded in a non-Xen-booted kernel. Just checked the source. Will only register the filesystem if returns non-zero, implying not running on bare metal. I might get around to scrounging up the requisite boot stages for the EFI boot and build myself a kernel to load. a few months ago I installed dom0 FreeBSD despite all the "xen can't boot EFI" history, and it came up without a hitch and ran, so that would be a good place to look as a reference. Or I could just look at my system.... Latest for was 4.15.1. I think they are up to 4.18 or so, so perhaps I will start with overlaying 4.18 just to get my feet wet with what is needed to build the kernel.
are u using the xen kernel variant (pkgs.linuxPackagesxendom0)?
Was not. Am now. Makes no difference. The infrastructure is not being deployed. In particular, the is not being installed. Need to boot Xen first, then load the dom0 kernel. I'm sort of interested in getting to the bottom of this (ie: getting it to work) but there is so much other stuff to learn / play with / ...
yeah i get that - ill ask around a bit on the nixos discord to see if anyone there is a bit more knowledgeable on this
Great. Thanks.
posted the question on there but nobody was answering :/ idk how else to help - xen feels like a deep rabbit hole to go down and i don't wanna do that right now hopefully someone in the future responds with steps on how to solve this
anything i can do to help with this ?
Xen now works on EFI. Required compilation changes to and a custom boot builder script.