GuixSD with custom kernel

config.scm

(define-module (my packages)
  #:use-module ((guix licenses) #:prefix license:)
  #:use-module (gnu packages linux)
  #:use-module (guix build-system trivial)
  #:use-module (gnu)
  #:use-module (guix download)
  #:use-module (guix git-download)
  #:use-module (guix packages))

(define (linux-nonfree-urls version)
  "Return a list of URLs for Linux-Nonfree VERSION."
  (list (string-append
         "https://www.kernel.org/pub/linux/kernel/v4.x/"
         "linux-" version ".tar.xz")))

;; Remove this and native-inputs below to use the default config from Guix.
;; Make sure the kernel minor version matches, though.
(define kernel-config
  (string-append (dirname (current-filename)) "/kernel.config"))

(define-public linux-nonfree
  (package
    (inherit linux-libre)
    (name "linux-nonfree")
    (version "4.13.11")
    (source (origin
              (method url-fetch)
              (uri (linux-nonfree-urls version))
              (sha256
               (base32
                "1vzl2i72c8iidhdc8a490npsbk7q7iphjqil4i9609disqw75gx4"))))
    (native-inputs
     `(("kconfig" ,kernel-config)
       ,@(alist-delete "kconfig"
                       (package-native-inputs linux-libre))))
    (synopsis "Mainline Linux kernel, nonfree binary blobs included")
    (description "Linux is a kernel.")
    (license license:gpl2)              ;XXX with proprietary firmware
    (home-page "https://kernel.org")))

(define (linux-firmware-version) "9d40a17beaf271e6ad47a5e714a296100eef4692")
(define (linux-firmware-source version)
  (origin
    (method git-fetch)
    (uri (git-reference
          (url (string-append "https://git.kernel.org/pub/scm/linux/kernel"
                              "/git/firmware/linux-firmware.git"))
          (commit version)))
    (file-name (string-append "linux-firmware-" version "-checkout"))
    (sha256
     (base32
      "099kll2n1zvps5qawnbm6c75khgn81j8ns0widiw0lnwm8s9q6ch"))))

(define-public iwlwifi-firmware-nonfree
  (package
    (name "iwlwifi-firmware-nonfree")
    (version (linux-firmware-version))
    (source (linux-firmware-source version))
    (build-system trivial-build-system)
    (arguments
     `(#:modules ((guix build utils))
       #:builder (begin
                   (use-modules (guix build utils))
                   (let ((source (assoc-ref %build-inputs "source"))
                         (fw-dir (string-append %output "/lib/firmware/")))
                     (mkdir-p fw-dir)
                     (for-each (lambda (file)
                                 (copy-file file
                                            (string-append fw-dir (basename file))))
                               (find-files source
                                           "iwlwifi-.*\\.ucode$|LICENSE\\.iwlwifi_firmware$"))
                     #t))))
    (home-page "https://wireless.wiki.kernel.org/en/users/drivers/iwlwifi")
    (synopsis "Non-free firmware for Intel wifi chips")
    (description "Non-free iwlwifi firmware")
    (license (license:non-copyleft
              "https://git.kernel.org/cgit/linux/kernel/git/firmware/linux-firmware.git/tree/LICENCE.iwlwifi_firmware?id=HEAD"))))



(define %sysctl-activation-service
  (simple-service 'sysctl activation-service-type
		  #~(let ((sysctl
			   (lambda (str)
			     (zero? (apply system*
					   #$(file-append procps
							  "/sbin/sysctl")
					   "-w" (string-tokenize str))))))
		      (and
		       ;; Enable IPv6 privacy extensions.
		       (sysctl "net.ipv6.conf.eth0.use_tempaddr=2")
		       ;; Enable SYN cookie protection.
		       (sysctl "net.ipv4.tcp_syncookies=1")
		       ;; Log Martian packets.
		       (sysctl "net.ipv4.conf.default.log_martians=1")))))

(define %powertop-service
  (simple-service 'powertop activation-service-type
		  #~(zero? (system* #$(file-append powertop "/sbin/powertop")
				    "--auto-tune"))))



(use-modules (gnu)
             (guix store)               ;for %default-substitute-urls
             (gnu system nss)
             (my packages)
             (srfi srfi-1))
(use-service-modules admin base dbus desktop mcron networking ssh xorg sddm)
(use-package-modules admin bootloaders certs disk fonts file emacs
                     libusb linux version-control
                     ssh tls tmux wm xdisorg xorg)

(operating-system
  (host-name "kirby")
  (timezone "Europe/Oslo")
  (kernel linux-nonfree)
  (kernel-arguments '("modprobe.blacklist=pcspkr,snd_pcsp"))
  ;; (locale "en_GB.utf8")
  ;; (locale-libcs (list glibc-2.24 (canonical-package glibc)))
  (firmware (append (list
                     iwlwifi-firmware-nonfree)
                    %base-firmware))

  (mapped-devices (list (mapped-device
                         (source "/dev/sda4")
                         (type luks-device-mapping)
                         (target "guixhome"))))

  (bootloader (bootloader-configuration
               (bootloader grub-efi-bootloader)
               (target "/boot/efi")))

  (file-systems (cons* (file-system
                         (device "guixroot")
                         (title 'label)
                         (mount-point "/")
                         (needed-for-boot? #t)
                         (type "ext4"))
                       (file-system
                         (device "/dev/mapper/guixhome")
                         (mount-point "/home")
                         (type "ext4"))
                       (file-system
                         (device "/dev/sda2")
                         (mount-point "/boot")
                         (type "vfat"))
                       %base-file-systems))

  (groups (cons (user-group
                 (name "marius"))
                %base-groups))
  (users (cons (user-account
                (name "marius")
                (comment "Meh")
                (group "marius")
                (supplementary-groups '("wheel" "netdev" "audio" "video" "kvm" "disk"))
                (home-directory "/home/marius"))
               %base-user-accounts))

  (packages (cons*
             dosfstools
             nss-certs
             htop
             wpa-supplicant
             acpid
             i3-wm
             i3status
             xscreensaver
             %base-packages))
  (services (cons*
             (sddm-service)
             (screen-locker-service xscreensaver)
             (service wpa-supplicant-service-type)
             (service network-manager-service-type)
             (upower-service)
             (colord-service)
             ;;(geoclue-service)
             (polkit-service)
             (elogind-service)
             (dbus-service)
             (service rottlog-service-type (rottlog-configuration))
             (service mcron-service-type)
	     %sysctl-activation-service
	     %powertop-service

             ;; Add udev rules for MTP devices so that non-root users can access
             ;; them.
             (simple-service 'mtp udev-service-type (list libmtp))

             ;; Store the current configuration with the generation.
             (simple-service 'store-my-config
                             etc-service-type
                             `(("current-config.scm"
                                ,(local-file (assoc-ref
                                              (current-source-location)
                                              'filename)))))
             (ntp-service #:servers '("nissen.uio.no"
                                      "2.no.pool.ntp.org"
                                      "1.no.pool.ntp.org"
                                      "0.sv.pool.ntp.org"))
             (modify-services %base-services
               (guix-service-type
                config =>
                (guix-configuration
                 (inherit config)
                 (substitute-urls
                  (cons* "http://192.168.2.11:8181"
                         "http://192.168.2.5:3000"
                         "http://137.205.52.16"
                         %default-substitute-urls))))))))

I used this as a template for setting up a custom kernel 4.15.6 as of today. Took some finessing to figure out how to get and assign version and sha256 hashes, but everything works smoothly here, and I can have some wifi at last on my mostly libre machine. Ask me if you have a question with getting a custom kernel to boot your guixSD

Do you a recipe of the steps you followed to set up the custom kernel??