397 lines
		
	
	
	
		
			16 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
			
		
		
	
	
			397 lines
		
	
	
	
		
			16 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2016 Christine Lemmer-Webber <cwebber@dustycloud.org>
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;;; Copyright © 2016, 2017 Leo Famulari <leo@famulari.name>
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;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
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;;; Copyright © 2017 Marius Bakke <mbakke@fastmail.com>
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;;; Copyright © 2018 Chris Marusich <cmmarusich@gmail.com>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu system vm)
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  #:use-module (guix config)
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  #:use-module (guix store)
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  #:use-module (guix gexp)
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  #:use-module (guix derivations)
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  #:use-module (guix packages)
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  #:use-module (guix monads)
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  #:use-module (guix records)
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  #:use-module (guix modules)
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  #:use-module (guix utils)
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  #:use-module (gcrypt hash)
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  #:use-module (guix base32)
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  #:use-module ((guix self) #:select (make-config.scm))
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  #:use-module ((gnu build marionette)
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                #:select (qemu-command))
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  #:use-module (gnu packages base)
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  #:use-module (gnu packages bootloaders)
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  #:use-module (gnu packages cdrom)
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  #:use-module (gnu packages compression)
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  #:use-module (gnu packages guile)
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  #:autoload   (gnu packages gnupg) (guile-gcrypt)
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  #:use-module (gnu packages gawk)
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  #:use-module (gnu packages bash)
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  #:use-module (gnu packages virtualization)
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  #:use-module (gnu packages disk)
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  #:use-module (gnu packages linux)
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  #:use-module (gnu bootloader)
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  #:use-module (gnu bootloader grub)
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  #:use-module (gnu image)
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  #:use-module (gnu system image)
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  #:use-module (gnu system linux-container)
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  #:use-module (gnu system linux-initrd)
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  #:use-module (gnu bootloader)
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  #:use-module (gnu system file-systems)
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  #:use-module (gnu system)
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  #:use-module (gnu services)
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  #:use-module (gnu services base)
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  #:use-module (gnu system uuid)
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  #:use-module ((srfi srfi-1) #:hide (partition))
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  #:use-module (srfi srfi-26)
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  #:use-module (rnrs bytevectors)
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  #:use-module (ice-9 match)
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  #:export (virtualized-operating-system
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            system-qemu-image/shared-store-script
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            virtual-machine
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            virtual-machine?))
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;;; Commentary:
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;;;
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;;; Tools to evaluate build expressions within virtual machines.
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;;;
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;;; Code:
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;; By default, the msize value is 8 KiB, which according to QEMU is
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;; insufficient and would degrade performance.  The msize value should roughly
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;; match the bandwidth of the system's IO (see:
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;; https://wiki.qemu.org/Documentation/9psetup#msize).  Use 100 MiB as a
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;; conservative default.
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(define %default-msize-value (* 100 (expt 2 20))) ;100 MiB
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(define %linux-vm-file-systems
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  ;; File systems mounted for 'derivation-in-linux-vm'.  These are shared with
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  ;; the host over 9p.
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  ;;
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  ;; The 9p documentation says that cache=loose is "intended for exclusive,
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  ;; read-only mounts", without additional details.  It's much faster than the
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  ;; default cache=none, especially when copying and registering store items.
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  ;; Thus, use cache=loose, except for /xchg where we want to ensure
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  ;; consistency.
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  (list (file-system
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          (mount-point (%store-prefix))
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          (device "store")
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          (type "9p")
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          (needed-for-boot? #t)
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          (flags '(read-only))
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          (options (format #f "trans=virtio,cache=loose,msize=~a"
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                           %default-msize-value))
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          (check? #f))
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        (file-system
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          (mount-point "/xchg")
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          (device "xchg")
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          (type "9p")
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          (needed-for-boot? #t)
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          (options (format #f "trans=virtio,msize=~a" %default-msize-value))
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          (check? #f))
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        (file-system
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          (mount-point "/tmp")
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          (device "tmp")
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          (type "9p")
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          (needed-for-boot? #t)
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          (options (format #f "trans=virtio,cache=loose,msize=~a"
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                           %default-msize-value))
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          (check? #f))))
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;;;
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;;; VMs that share file systems with the host.
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;;;
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(define (file-system->mount-tag fs)
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  "Return a 9p mount tag for host file system FS."
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  ;; QEMU mount tags must be ASCII, at most 31-byte long, cannot contain
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  ;; slashes, and cannot start with '_'.  Compute an identifier that
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  ;; corresponds to the rules.
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  (string-append "TAG"
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                 (string-drop (bytevector->base32-string
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                               (sha1 (string->utf8 fs)))
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                              4)))
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(define (mapping->file-system mapping)
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  "Return a 9p file system that realizes MAPPING."
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  (match mapping
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    (($ <file-system-mapping> source target writable?)
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     (file-system
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       (mount-point target)
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       (device (file-system->mount-tag source))
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       (type "9p")
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       (flags (if writable? '() '(read-only)))
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       (options (string-append "trans=virtio"
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                               (if writable? "" ",cache=loose")
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                               ",msize=" (number->string %default-msize-value)))
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       (check? #f)
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       (create-mount-point? #t)))))
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(define* (virtualized-operating-system os mappings
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                                       #:key (full-boot? #f) volatile?)
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  "Return an operating system based on OS suitable for use in a virtualized
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environment with the store shared with the host.  MAPPINGS is a list of
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<file-system-mapping> to realize in the virtualized OS."
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  (define user-file-systems
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    ;; Remove file systems that conflict with those added below, or that are
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    ;; normally bound to real devices.
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    (remove (lambda (fs)
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              (let ((target (file-system-mount-point fs))
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                    (source (file-system-device fs)))
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                (or (string=? target (%store-prefix))
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                    (string=? target "/")
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                    (and (string? source)
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                         (string-prefix? "/dev/" source))
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                    ;; Labels and UUIDs are necessarily invalid in the VM.
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                    (and (file-system-mount? fs)
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                         (or (file-system-label? source)
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                             (uuid? source))))))
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            (operating-system-file-systems os)))
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  (define virtual-file-systems
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    (cons (file-system
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            (mount-point "/")
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            (device "/dev/vda1")
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            (type "ext4"))
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          (append (map mapping->file-system mappings)
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                  user-file-systems)))
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  (operating-system (inherit os)
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    ;; XXX: Until we run QEMU with UEFI support (with the OVMF firmware),
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    ;; force the traditional i386/BIOS method.
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    ;; See <https://bugs.gnu.org/28768>.
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    (bootloader (bootloader-configuration
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                  (inherit (operating-system-bootloader os))
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                  (bootloader grub-bootloader)
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                  (targets '("/dev/vda"))))
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    (initrd (lambda (file-systems . rest)
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              (apply (operating-system-initrd os)
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                     file-systems
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                     #:volatile-root? volatile?
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                     rest)))
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    ;; Disable swap.
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    (swap-devices '())
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    ;; XXX: When FULL-BOOT? is true, do not add a 9p mount for /gnu/store
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    ;; since that would lead the bootloader config to look for the kernel and
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    ;; initrd in it.
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    (file-systems (if full-boot?
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                      virtual-file-systems
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                      (cons
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                       (file-system
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                         (inherit (mapping->file-system %store-mapping))
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                         (needed-for-boot? #t))
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                       virtual-file-systems)))))
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(define* (common-qemu-options image shared-fs
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                              #:key rw-image?)
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  "Return the a string-value gexp with the common QEMU options to boot IMAGE,
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with '-virtfs' options for the host file systems listed in SHARED-FS."
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  (define (virtfs-option fs)
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    #~(format #f "-virtfs local,path=~s,security_model=none,mount_tag=~s"
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              #$fs #$(file-system->mount-tag fs)))
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  #~(;; Only enable kvm if we see /dev/kvm exists.
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     ;; This allows users without hardware virtualization to still use these
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     ;; commands.
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     #$@(if (file-exists? "/dev/kvm")
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            '("-enable-kvm")
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            '())
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     "-no-reboot"
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     "-object" "rng-random,filename=/dev/urandom,id=guix-vm-rng"
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     "-device" "virtio-rng-pci,rng=guix-vm-rng"
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     #$@(map virtfs-option shared-fs)
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     #$@(if rw-image?
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            #~((format #f "-drive file=~a,if=virtio" #$image))
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            #~((format #f "-drive file=~a,if=virtio,cache=writeback,werror=report,readonly=on"
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                       #$image)))))
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(define* (system-qemu-image/shared-store-script os
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                                                #:key
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                                                (system (%current-system))
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                                                (target (%current-target-system))
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                                                (qemu qemu)
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                                                (graphic? #t)
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                                                (volatile? #t)
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                                                (memory-size 512)
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                                                (mappings '())
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                                                full-boot?
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                                                (disk-image-size
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                                                 (* (if full-boot? 500 70)
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                                                    (expt 2 20)))
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                                                (options '()))
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  "Return a derivation that builds a script to run a virtual machine image of
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OS that shares its store with the host.  The virtual machine runs with
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MEMORY-SIZE MiB of memory.
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MAPPINGS is a list of <file-system-mapping> specifying mapping of host file
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systems into the guest.
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When FULL-BOOT? is true, the returned script runs everything starting from the
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bootloader; otherwise it directly starts the operating system kernel.  When
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VOLATILE? is true, an overlay is created on top of a read-only
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storage. Otherwise the storage is made persistent.  The DISK-IMAGE-SIZE
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parameter specifies the size in bytes of the root disk image; it is mostly
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useful when FULL-BOOT?  is true."
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  (mlet* %store-monad ((os ->  (virtualized-operating-system
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                                os mappings
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                                #:full-boot? full-boot?
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                                #:volatile? volatile?))
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                       (base-image -> (system-image
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                                       (image
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                                        (inherit
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                                         (raw-with-offset-disk-image))
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                                        (operating-system os)
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                                        (size disk-image-size)
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                                        (shared-store?
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                                         (and (not full-boot?) volatile?))
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                                        (volatile-root? volatile?)))))
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    (define kernel-arguments
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      #~(list #$@(if graphic? #~() #~("console=ttyS0"))
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              #+@(operating-system-kernel-arguments os "/dev/vda1")))
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    (define rw-image
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      #~(format #f "/tmp/guix-image-~a" (basename #$base-image)))
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    (define qemu-exec
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      #~(list #+(file-append qemu "/bin/"
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                             (qemu-command (or target system)))
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              ;; Tells qemu to use the terminal it was started in for IO.
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              #$@(if graphic? '() #~("-nographic"))
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              #$@(if full-boot?
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                     #~()
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                     #~("-kernel" #$(operating-system-kernel-file os)
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                        "-initrd" #$(file-append os "/initrd")
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                        (format #f "-append ~s"
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                                (string-join #$kernel-arguments " "))))
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              #$@(common-qemu-options (if volatile? base-image rw-image)
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                                      (map file-system-mapping-source
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                                           (cons %store-mapping mappings))
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                                      #:rw-image? (not volatile?))
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              "-m " (number->string #$memory-size)
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              #$@options))
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    (define builder
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      #~(call-with-output-file #$output
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          (lambda (port)
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            (format port "#!~a~%"
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                    #+(file-append bash "/bin/sh"))
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            (when (not #$volatile?)
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              (format port "~a~%"
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                      #$(program-file "copy-image"
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                                      #~(unless (file-exists? #$rw-image)
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                                          (copy-file #$base-image #$rw-image)
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                                          (chmod #$rw-image #o640)))))
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            (format port "exec ~a \"$@\"~%"
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                    (string-join #$qemu-exec " "))
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            (chmod port #o555))))
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    (gexp->derivation "run-vm.sh" builder)))
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;;;
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;;; High-level abstraction.
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;;;
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(define-record-type* <virtual-machine> %virtual-machine
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  make-virtual-machine
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  virtual-machine?
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  (operating-system virtual-machine-operating-system) ;<operating-system>
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  (qemu             virtual-machine-qemu              ;<package>
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                    (default qemu-minimal))
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  (volatile?        virtual-machine-volatile?    ;Boolean
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                    (default #t))
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  (graphic?         virtual-machine-graphic?      ;Boolean
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                    (default #f))
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  (memory-size      virtual-machine-memory-size   ;integer (MiB)
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                    (default 256))
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  (disk-image-size  virtual-machine-disk-image-size   ;integer (bytes)
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                    (default 'guess))
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  (port-forwardings virtual-machine-port-forwardings ;list of integer pairs
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                    (default '())))
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(define-syntax virtual-machine
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  (syntax-rules ()
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    "Declare a virtual machine running the specified OS, with the given
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options."
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    ((_ os)                                       ;shortcut
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     (%virtual-machine (operating-system os)))
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    ((_ fields ...)
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     (%virtual-machine fields ...))))
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(define (port-forwardings->qemu-options forwardings)
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  "Return the QEMU option for the given port FORWARDINGS as a string, where
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FORWARDINGS is a list of host-port/guest-port pairs."
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  (string-join
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   (map (match-lambda
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          ((host-port . guest-port)
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           (string-append "hostfwd=tcp::"
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                          (number->string host-port)
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                          "-:" (number->string guest-port))))
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        forwardings)
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   ","))
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(define-gexp-compiler (virtual-machine-compiler (vm <virtual-machine>)
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                                                system target)
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  (match vm
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    (($ <virtual-machine> os qemu volatile? graphic? memory-size
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                          disk-image-size ())
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     (system-qemu-image/shared-store-script os
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                                            #:system system
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                                            #:target target
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                                            #:qemu qemu
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                                            #:graphic? graphic?
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                                            #:volatile? volatile?
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                                            #:memory-size memory-size
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                                            #:disk-image-size
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                                            disk-image-size))
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    (($ <virtual-machine> os qemu volatile? graphic? memory-size
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                          disk-image-size forwardings)
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     (let ((options
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            `("-nic" ,(string-append
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                       "user,model=virtio-net-pci,"
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                       (port-forwardings->qemu-options forwardings)))))
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       (system-qemu-image/shared-store-script os
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                                              #:system system
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                                              #:target target
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                                              #:qemu qemu
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                                              #:graphic? graphic?
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                                              #:volatile? volatile?
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                                              #:memory-size memory-size
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                                              #:disk-image-size
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                                              disk-image-size
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                                              #:options options)))))
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;;; vm.scm ends here
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