gnu: Allow services to install kernel-loadable modules.

* gnu/system.scm (operating-system-directory-base-entries): Remove code
to handle generation of "kernel" for linux-libre kernels.
(operating-system-default-essential-services): Instantiate
linux-builder-service-type.
(package-for-kernel): Move ...
* gnu/services.scm: ... to here.
(linux-builder-service-type): New variable.
(linux-builder-configuration): New type.
(linux-loadable-module-service-type): New variable.
* gnu/tests/linux-modules.scm (run-loadable-kernel-modules-test): Move
code to ...
(run-loadable-kernel-modules-test-base): ... new procedure here.
(run-loadable-kernel-modules-service-test): New procedure.
(%test-loadable-kernel-modules-service-0): New variable.
(%test-loadable-kernel-modules-service-1): New variable.
(%test-loadable-kernel-modules-service-2): New variable.
* doc/guix.texi: Document linux-loadable-module-service-type.

Signed-off-by: Danny Milosavljevic <dannym@scratchpost.org>

3 files changed, 169 insertions, 35 deletions

diff --git a/gnu/services.scm b/gnu/services.scm
index e7da0a026d8..8d413e198e6 100644
--- a/gnu/services.scm
+++ b/gnu/services.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
 ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;; Copyright © 2020, 2021 Ricardo Wurmus <rekado@elephly.net>
+;;; Copyright © 2021 raid5atemyhomework <raid5atemyhomework@protonmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -34,6 +35,8 @@
   #:use-module (guix diagnostics)
   #:autoload   (guix openpgp) (openpgp-format-fingerprint)
   #:use-module (guix modules)
+  #:use-module (guix packages)
+  #:use-module (guix utils)
   #:use-module (gnu packages base)
   #:use-module (gnu packages bash)
   #:use-module (gnu packages hurd)
@@ -107,6 +110,12 @@
             profile-service-type
             firmware-service-type
             gc-root-service-type
+            linux-builder-service-type
+            linux-builder-configuration
+            linux-builder-configuration?
+            linux-builder-configuration-kernel
+            linux-builder-configuration-modules
+            linux-loadable-module-service-type
 
             %boot-service
             %activation-service
@@ -883,6 +892,87 @@ as Wifi cards.")))
 will not be reclaimed by the garbage collector.")
                 (default-value '())))
 
+;; Configuration for the Linux kernel builder.
+(define-record-type* <linux-builder-configuration>
+  linux-builder-configuration
+  make-linux-builder-configuration
+  linux-builder-configuration?
+  this-linux-builder-configuration
+
+  (kernel   linux-builder-configuration-kernel)                   ; package
+  (modules  linux-builder-configuration-modules  (default '())))  ; list of packages
+
+(define (package-for-kernel target-kernel module-package)
+  "Return a package like MODULE-PACKAGE, adapted for TARGET-KERNEL, if
+possible (that is if there's a LINUX keyword argument in the build system)."
+  (package
+    (inherit module-package)
+    (arguments
+     (substitute-keyword-arguments (package-arguments module-package)
+       ((#:linux kernel #f)
+        target-kernel)))))
+
+(define (linux-builder-configuration->system-entry config)
+  "Return the kernel entry of the 'system' directory."
+  (let* ((kernel  (linux-builder-configuration-kernel config))
+         (modules (linux-builder-configuration-modules config))
+         (kernel  (profile
+                    (content (packages->manifest
+                              (cons kernel
+                                    (map (lambda (module)
+                                           (cond
+                                             ((package? module)
+                                              (package-for-kernel kernel module))
+                                             ;; support (,package "kernel-module-output")
+                                             ((and (list? module) (package? (car module)))
+                                              (cons (package-for-kernel kernel
+                                                                        (car module))
+                                                    (cdr module)))
+                                             (else
+                                              module)))
+                                         modules))))
+                    (hooks (list linux-module-database)))))
+    (with-monad %store-monad
+      (return `(("kernel" ,kernel))))))
+
+(define linux-builder-service-type
+  (service-type (name 'linux-builder)
+                (extensions
+                  (list (service-extension system-service-type
+                                           linux-builder-configuration->system-entry)))
+                (default-value '())
+                (compose identity)
+                (extend (lambda (config modifiers)
+                          (if (null? modifiers)
+                              config
+                              ((apply compose modifiers) config))))
+                (description "Builds the linux-libre kernel profile, containing
+the kernel itself and any linux-loadable kernel modules.  This can be extended
+with a function that accepts the current configuration and returns a new
+configuration.")))
+
+(define (linux-loadable-module-builder-modifier modules)
+  "Extends linux-builder-service-type by appending the given MODULES to the
+configuration of linux-builder-service-type."
+  (lambda (config)
+    (linux-builder-configuration
+      (inherit config)
+      (modules (append (linux-builder-configuration-modules config)
+                       modules)))))
+
+(define linux-loadable-module-service-type
+  (service-type (name 'linux-loadable-modules)
+                (extensions
+                  (list (service-extension linux-builder-service-type
+                                           linux-loadable-module-builder-modifier)))
+                (default-value '())
+                (compose concatenate)
+                (extend append)
+                (description "Adds packages and package outputs as modules
+included in the booted linux-libre profile.  Other services can extend this
+service type to add particular modules to the set of linux-loadable modules.")))
+
+
 
 ;;;
 ;;; Service folding.
diff --git a/gnu/system.scm b/gnu/system.scm
index 5bf2a852729..7cc4f134b71 100644
--- a/gnu/system.scm
+++ b/gnu/system.scm
@@ -13,6 +13,7 @@
 ;;; Copyright © 2020 Jan (janneke) Nieuwenhuizen <jannek@gnu.org>
 ;;; Copyright © 2020 Efraim Flashner <efraim@flashner.co.il>
 ;;; Copyright © 2021 Maxime Devos <maximedevos@telenet.be>
+;;; Copyright © 2021 raid5atemyhomework <raid5atemyhomework@protonmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -601,16 +602,6 @@ OS."
       (file-append (operating-system-kernel os)
                       "/" (system-linux-image-file-name))))
 
-(define (package-for-kernel target-kernel module-package)
-  "Return a package like MODULE-PACKAGE, adapted for TARGET-KERNEL, if
-possible (that is if there's a LINUX keyword argument in the build system)."
-  (package
-    (inherit module-package)
-    (arguments
-     (substitute-keyword-arguments (package-arguments module-package)
-       ((#:linux kernel #f)
-        target-kernel)))))
-
 (define %default-modprobe-blacklist
   ;; List of kernel modules to blacklist by default.
   '("usbmouse" ;races with bcm5974, see <https://bugs.gnu.org/35574>
@@ -628,23 +619,12 @@ value of the SYSTEM-SERVICE-TYPE service."
   (let* ((locale  (operating-system-locale-directory os))
          (kernel  (operating-system-kernel os))
          (hurd    (operating-system-hurd os))
-         (modules (operating-system-kernel-loadable-modules os))
-         (kernel  (if hurd
-                      kernel
-                      (profile
-                       (content (packages->manifest
-                                 (cons kernel
-                                       (map (lambda (module)
-                                              (if (package? module)
-                                                  (package-for-kernel kernel
-                                                                      module)
-                                                  module))
-                                            modules))))
-                       (hooks (list linux-module-database)))))
          (initrd  (and (not hurd) (operating-system-initrd-file os)))
          (params  (operating-system-boot-parameters-file os)))
-    `(("kernel" ,kernel)
-      ,@(if hurd `(("hurd" ,hurd)) '())
+    `(,@(if hurd
+          `(("hurd" ,hurd)
+            ("kernel" ,kernel))
+          '())
       ("parameters" ,params)
       ,@(if initrd `(("initrd" ,initrd)) '())
       ("locale" ,locale))))   ;used by libc
@@ -664,6 +644,10 @@ bookkeeping."
          (host-name (host-name-service (operating-system-host-name os)))
          (entries   (operating-system-directory-base-entries os)))
     (cons* (service system-service-type entries)
+           (service linux-builder-service-type
+                    (linux-builder-configuration
+                      (kernel   (operating-system-kernel os))
+                      (modules  (operating-system-kernel-loadable-modules os))))
            %boot-service
 
            ;; %SHEPHERD-ROOT-SERVICE must come last so that the gexp that
diff --git a/gnu/tests/linux-modules.scm b/gnu/tests/linux-modules.scm
index 953b132ef7b..30d8eae03b8 100644
--- a/gnu/tests/linux-modules.scm
+++ b/gnu/tests/linux-modules.scm
@@ -2,6 +2,7 @@
 ;;; Copyright © 2019 Jakob L. Kreuze <zerodaysfordays@sdf.org>
 ;;; Copyright © 2020 Danny Milosavljevic <dannym@scratchpost.org>
 ;;; Copyright © 2020 Brice Waegeneire <brice@waegenei.re>
+;;; Copyright © 2021 raid5atemyhomework <raid5atemyhomework@protonmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -34,7 +35,10 @@
   #:use-module (guix utils)
   #:export (%test-loadable-kernel-modules-0
             %test-loadable-kernel-modules-1
-            %test-loadable-kernel-modules-2))
+            %test-loadable-kernel-modules-2
+            %test-loadable-kernel-modules-service-0
+            %test-loadable-kernel-modules-service-1
+            %test-loadable-kernel-modules-service-2))
 
 ;;; Commentary:
 ;;;
@@ -66,17 +70,11 @@ that MODULES are actually loaded."
                        (member module modules string=?))
                      '#$modules))))))
 
-(define* (run-loadable-kernel-modules-test module-packages module-names)
-  "Run a test of an OS having MODULE-PACKAGES, and verify that MODULE-NAMES
-are loaded in memory."
+(define* (run-loadable-kernel-modules-test-base base-os module-names)
+  "Run a test of BASE-OS, verifying that MODULE-NAMES are loaded in memory."
   (define os
     (marionette-operating-system
-     (operating-system
-      (inherit (simple-operating-system))
-      (services (cons (service kernel-module-loader-service-type module-names)
-                      (operating-system-user-services
-                       (simple-operating-system))))
-      (kernel-loadable-modules module-packages))
+     base-os
      #:imported-modules '((guix combinators))))
   (define vm (virtual-machine os))
   (define (test script)
@@ -98,6 +96,36 @@ are loaded in memory."
   (gexp->derivation "loadable-kernel-modules"
                     (test (modules-loaded?-program os module-names))))
 
+(define* (run-loadable-kernel-modules-test module-packages module-names)
+  "Run a test of an OS having MODULE-PACKAGES, and verify that MODULE-NAMES
+are loaded in memory."
+  (run-loadable-kernel-modules-test-base
+    (operating-system
+      (inherit (simple-operating-system))
+      (services (cons (service kernel-module-loader-service-type module-names)
+                      (operating-system-user-services
+                       (simple-operating-system))))
+      (kernel-loadable-modules module-packages))
+    module-names))
+
+(define* (run-loadable-kernel-modules-service-test module-packages module-names)
+  "Run a test of an OS having MODULE-PACKAGES, which are loaded by creating a
+service that extends LINUXL-LOADABLE-MODULE-SERVICE-TYPE. Then verify that
+MODULE-NAMES are loaded in memory."
+  (define module-installing-service-type
+    (service-type
+      (name 'module-installing-service)
+      (extensions (list (service-extension linux-loadable-module-service-type
+                                           (const module-packages))))
+      (default-value #f)))
+  (run-loadable-kernel-modules-test-base
+    (operating-system
+      (inherit (simple-operating-system))
+      (services (cons* (service module-installing-service-type)
+                       (operating-system-user-services
+                        (simple-operating-system)))))
+    module-names))
+
 (define %test-loadable-kernel-modules-0
   (system-test
    (name "loadable-kernel-modules-0")
@@ -129,3 +157,35 @@ with two extra modules.")
                                                  (package-arguments
                                                   ddcci-driver-linux))))))
            '("acpi_call" "ddcci")))))
+
+(define %test-loadable-kernel-modules-service-0
+  (system-test
+   (name "loadable-kernel-modules-service-0")
+   (description "Tests loadable kernel modules extensible service with no
+extra modules.")
+   (value (run-loadable-kernel-modules-service-test '() '()))))
+
+(define %test-loadable-kernel-modules-service-1
+  (system-test
+   (name "loadable-kernel-modules-service-1")
+   (description "Tests loadable kernel modules extensible service with one
+extra module.")
+   (value (run-loadable-kernel-modules-service-test
+           (list ddcci-driver-linux)
+           '("ddcci")))))
+
+(define %test-loadable-kernel-modules-service-2
+  (system-test
+   (name "loadable-kernel-modules-service-2")
+   (description "Tests loadable kernel modules extensible service with two
+extra modules.")
+   (value (run-loadable-kernel-modules-service-test
+           (list acpi-call-linux-module
+                 (package
+                   (inherit ddcci-driver-linux)
+                   (arguments
+                    `(#:linux #f
+                      ,@(strip-keyword-arguments '(#:linux)
+                                                 (package-arguments
+                                                  ddcci-driver-linux))))))
+           '("acpi_call" "ddcci")))))