Subject: [PATCH v1] initrd: Allow extra search paths with ‘initrd-extra-module-paths’

From: Brian Cully <[email-masked]>
Date: Mon, 2 May 2022 15:11:30 -0400

This patch allows copying of out-of-tree kernel modules to the Linux
initrd.

For out-of-tree modules to found, an extra slot has been added to
‘operating-system’: ‘initrd-extra-module-paths’, which contains a list
containing items of either FILE-LIKE or (FILE-LIKE OUTPUT) which will be
searched for modules in addition to the standard Linux module path. The
required modules can then be added to ‘initrd-modules’ as normal and all paths
will be searched for it, including for any modules depended on.

* gnu/build/linux-modules.scm (find-module-file): change DIRECTORY argument to
DIRECTORIES. Now takes a list of directories to search, rather than a single
one.
* gnu/system.scm <operating-system>: Add INITRD-EXTRA-MODULE-PATHS
field and accessor. Takes a list of file-like objects.
* gnu/system/linux-initrd.scm (flat-linux-module-directory): change LINUX
argument to PACKAGES. Now contains a list of file-likes to search for modules.
(raw-initrd): Add LINUX-EXTRA-MODULE-PATHS keyword argument. Pass it
to (flat-linux-extra-module-paths) along with the selected LINUX package.
(base-initrd): Add LINUX-EXTRA-MODULE-PATHS keyword argument. Pass it
to (raw-initrd).
---
 gnu/build/linux-modules.scm | 19 ++++++++------
 gnu/system.scm              |  5 ++++
 gnu/system/linux-initrd.scm | 52 +++++++++++++++++++++++++------------
 3 files changed, 51 insertions(+), 25 deletions(-)

diff --git a/gnu/build/linux-modules.scm b/gnu/build/linux-modules.scm
index 053720574b..97b7e429ea 100644
--- a/gnu/build/linux-modules.scm
+++ b/gnu/build/linux-modules.scm
@@ -225,8 +225,8 @@ (define (file-name->module-name file)
 '.ko[.gz|.xz]' and normalizing it."
   (normalize-module-name (strip-extension (basename file))))
 
-(define (find-module-file directory module)
-  "Lookup module NAME under DIRECTORY, and return its absolute file name.
+(define (find-module-file directories module)
+  "Lookup module NAME under DIRECTORIES, and return its absolute file name.
 NAME can be a file name with or without '.ko', or it can be a module name.
 Raise an error if it could not be found.
 
@@ -247,16 +247,19 @@ (define names
                            (else chr)))
                        module))))
 
-  (match (find-files directory
-                     (lambda (file stat)
-                       (member (strip-extension
-                                (basename file)) names)))
+  (match (append-map (lambda (directory)
+                       (find-files directory
+                                   (lambda (file _stat)
+                                     (member (strip-extension
+                                              (basename file))
+                                             names))))
+                       directories)
     ((file)
      file)
     (()
-     (error "kernel module not found" module directory))
+     (error "kernel module not found" module directories))
     ((_ ...)
-     (error "several modules by that name" module directory))))
+     (error "several modules by that name" module directories))))
 
 (define* (recursive-module-dependencies files
                                         #:key (lookup-module dot-ko))
diff --git a/gnu/system.scm b/gnu/system.scm
index c3810cbeeb..15ac30c933 100644
--- a/gnu/system.scm
+++ b/gnu/system.scm
@@ -103,6 +103,7 @@ (define-module (gnu system)
             operating-system-label
             operating-system-default-label
             operating-system-initrd-modules
+            operating-system-initrd-extra-module-paths
             operating-system-initrd
             operating-system-users
             operating-system-groups
@@ -232,6 +233,8 @@ (define-record-type* <operating-system> operating-system
   (initrd-modules operating-system-initrd-modules ; list of strings
                   (thunked)                       ; it's system-dependent
                   (default %base-initrd-modules))
+  (initrd-extra-module-paths operating-system-initrd-extra-module-paths ; list of file-likes
+                             (default '()))
 
   (firmware operating-system-firmware             ; list of packages
             (default %base-firmware))
@@ -1307,6 +1310,8 @@ (define make-initrd
                #:linux (operating-system-kernel os)
                #:linux-modules
                (operating-system-initrd-modules os)
+               #:linux-extra-module-paths
+               (operating-system-initrd-extra-module-paths os)
                #:mapped-devices mapped-devices
                #:keyboard-layout (operating-system-keyboard-layout os)))
 
diff --git a/gnu/system/linux-initrd.scm b/gnu/system/linux-initrd.scm
index 4c4c78e444..50a182d7d5 100644
--- a/gnu/system/linux-initrd.scm
+++ b/gnu/system/linux-initrd.scm
@@ -119,13 +119,23 @@ (define builder
                               `(#:references-graphs (("closure" ,init))))
                "/initrd.cpio.gz"))
 
-(define (flat-linux-module-directory linux modules)
+(define (flat-linux-module-directory packages modules)
   "Return a flat directory containing the Linux kernel modules listed in
-MODULES and taken from LINUX."
+MODULES and taken from PACKAGES."
   (define imported-modules
     (source-module-closure '((gnu build linux-modules)
                              (guix build utils))))
 
+  (define (package+out->input package out)
+    (gexp-input package out))
+
+  (define package-inputs
+    (map (lambda (p)
+           (match p
+             ((p o) (package+out->input p o))
+             (p     (package+out->input p "out"))))
+         packages))
+
   (define build-exp
     (with-imported-modules imported-modules
       (with-extensions (list guile-zlib)
@@ -135,11 +145,12 @@ (define build-exp
                          (srfi srfi-1)
                          (srfi srfi-26))
 
-            (define module-dir
-              (string-append #$linux "/lib/modules"))
+            (define module-dirs
+              (map (cut string-append <> "/lib/modules")
+                   '#$package-inputs))
 
             (define modules
-              (let* ((lookup  (cut find-module-file module-dir <>))
+              (let* ((lookup  (cut find-module-file module-dirs <>))
                      (modules (map lookup '#$modules)))
                 (append modules
                         (recursive-module-dependencies
@@ -172,20 +183,23 @@ (define* (raw-initrd file-systems
                       #:key
                       (linux linux-libre)
                       (linux-modules '())
+                      (linux-extra-module-paths '())
                       (mapped-devices '())
                       (keyboard-layout #f)
                       (helper-packages '())
                       qemu-networking?
                       volatile-root?
                       (on-error 'debug))
-  "Return as a file-like object a raw initrd, with kernel
-modules taken from LINUX.  FILE-SYSTEMS is a list of file-systems to be
-mounted by the initrd, possibly in addition to the root file system specified
-on the kernel command line via 'root'.  LINUX-MODULES is a list of kernel
-modules to be loaded at boot time. MAPPED-DEVICES is a list of device
-mappings to realize before FILE-SYSTEMS are mounted.
-HELPER-PACKAGES is a list of packages to be copied in the initrd. It may include
-e2fsck/static or other packages needed by the initrd to check root partition.
+  "Return as a file-like object a raw initrd, with kernel modules taken from
+LINUX.  FILE-SYSTEMS is a list of file-systems to be mounted by the initrd,
+possibly in addition to the root file system specified on the kernel command
+line via 'root'.  LINUX-MODULES is a list of kernel modules to be loaded at
+boot time. LINUX-EXTRA-MODULE-PATHS is a list of file-like objects which will
+be searched for modules in addition to the linux kernel. MAPPED-DEVICES is a
+list of device mappings to realize before FILE-SYSTEMS are mounted.
+HELPER-PACKAGES is a list of packages to be copied in the initrd. It may
+include e2fsck/static or other packages needed by the initrd to check root
+partition.
 
 When true, KEYBOARD-LAYOUT is a <keyboard-layout> record denoting the desired
 console keyboard layout.  This is done before MAPPED-DEVICES are set up and
@@ -221,7 +235,8 @@ (define file-system-scan-commands
           #~())))
 
   (define kodir
-    (flat-linux-module-directory linux linux-modules))
+    (flat-linux-module-directory (cons linux linux-extra-module-paths)
+                                 linux-modules))
 
   (expression->initrd
    (with-imported-modules (source-module-closure
@@ -366,6 +381,7 @@ (define* (base-initrd file-systems
                       #:key
                       (linux linux-libre)
                       (linux-modules '())
+                      (linux-extra-module-paths '())
                       (mapped-devices '())
                       (keyboard-layout #f)
                       qemu-networking?
@@ -386,9 +402,10 @@ (define* (base-initrd file-systems
 QEMU-NETWORKING? and VOLATILE-ROOT? behaves as in raw-initrd.
 
 The initrd is automatically populated with all the kernel modules necessary
-for FILE-SYSTEMS and for the given options.  Additional kernel
-modules can be listed in LINUX-MODULES.  They will be added to the initrd, and
-loaded at boot time in the order in which they appear."
+for FILE-SYSTEMS and for the given options.  Additional kernel modules can be
+listed in LINUX-MODULES.  Additional search paths for modules can be listed in
+LINUX-EXTRA-MODULE-PATHS.  They will be added to the initrd, and loaded at
+boot time in the order in which they appear."
   (define linux-modules*
     ;; Modules added to the initrd and loaded from the initrd.
     `(,@linux-modules
@@ -408,6 +425,7 @@ (define helper-packages
   (raw-initrd file-systems
               #:linux linux
               #:linux-modules linux-modules*
+              #:linux-extra-module-paths linux-extra-module-paths
               #:mapped-devices mapped-devices
               #:helper-packages helper-packages
               #:keyboard-layout keyboard-layout

base-commit: 0a64b629ae8512790d532158a72a4a25698e8157
prerequisite-patch-id: 213ce2b9743f11d45836fe0794f117f3bb84063d
-- 
2.35.1