summaryrefslogtreecommitdiff
path: root/gnu/build/linux-modules.scm
blob: aa1c7cfeae2cad627ee8c44c3fff0208139e4822 (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2016, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2018 Danny Milosavljevic <dannym@scratchpost.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu build linux-modules)
  #:use-module (guix elf)
  #:use-module (guix glob)
  #:use-module (guix build syscalls)
  #:use-module ((guix build utils) #:select (find-files invoke))
  #:use-module (guix build union)
  #:use-module (rnrs io ports)
  #:use-module (rnrs bytevectors)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-11)
  #:use-module (srfi srfi-26)
  #:use-module (ice-9 ftw)
  #:use-module (ice-9 vlist)
  #:use-module (ice-9 match)
  #:use-module (ice-9 rdelim)
  #:autoload   (ice-9 pretty-print) (pretty-print)
  #:export (dot-ko
            ensure-dot-ko
            module-formal-name
            module-aliases
            module-dependencies
            module-soft-dependencies
            normalize-module-name
            file-name->module-name
            find-module-file
            recursive-module-dependencies
            modules-loaded
            module-loaded?
            load-linux-module*
            load-linux-modules-from-directory

            current-module-debugging-port

            device-module-aliases
            known-module-aliases
            matching-modules
            missing-modules

            write-module-name-database
            write-module-alias-database
            write-module-device-database

            make-linux-module-directory))

;;; Commentary:
;;;
;;; Tools to deal with Linux kernel modules.
;;;
;;; Code:

(define current-module-debugging-port
  (make-parameter (%make-void-port "w")))

(define (section-contents elf section)
  "Return the contents of SECTION in ELF as a bytevector."
  (let ((contents (make-bytevector (elf-section-size section))))
    (bytevector-copy! (elf-bytes elf) (elf-section-offset section)
                      contents 0
                      (elf-section-size section))
    contents))

(define %not-nul
  (char-set-complement (char-set #\nul)))

(define (nul-separated-string->list str)
  "Split STR at occurrences of the NUL character and return the resulting
string list."
  (string-tokenize str %not-nul))

(define (key=value->pair str)
  "Assuming STR has the form \"KEY=VALUE\", return a pair like (KEY
. \"VALUE\")."
  (let ((= (string-index str #\=)))
    (cons (string->symbol (string-take str =))
          (string-drop str (+ 1 =)))))

(define (modinfo-section-contents file)
  "Return the contents of the '.modinfo' section of FILE as a list of
key/value pairs.."
  (let* ((bv      (call-with-input-file file get-bytevector-all))
         (elf     (parse-elf bv))
         (section (elf-section-by-name elf ".modinfo"))
         (modinfo (section-contents elf section)))
    (map key=value->pair
         (nul-separated-string->list (utf8->string modinfo)))))

(define %not-comma
  (char-set-complement (char-set #\,)))

(define (module-formal-name file)
  "Return the module name of FILE as it appears in its info section.  Usually
the module name is the same as the base name of FILE, modulo hyphens and minus
the \".ko\" extension."
  (match (assq 'name (modinfo-section-contents file))
    (('name . name) name)
    (#f #f)))

(define (module-dependencies file)
  "Return the list of modules that FILE depends on.  The returned list
contains module names, not actual file names."
  (let ((info (modinfo-section-contents file)))
    (match (assq 'depends info)
      (('depends . what)
       (string-tokenize what %not-comma)))))

(define not-softdep-whitespace
  (char-set-complement (char-set #\space #\tab)))

(define (module-soft-dependencies file)
  "Return the list of modules that can be preloaded, and then the list of
modules that can be postloaded, of the soft dependencies of module FILE."
  ;; TEXT: "pre: baz blubb foo post: bax bar"
  (define (parse-softdep text)
    (let loop ((value '())
               (tokens (string-tokenize text not-softdep-whitespace))
               (section #f))
      (match tokens
       ((token rest ...)
        (if (string=? (string-take-right token 1) ":") ; section
            (loop value rest (string-trim-both (string-drop-right token 1)))
            (loop (cons (cons section token) value) rest section)))
       (()
        value))))

  ;; Note: Multiple 'softdep sections are allowed.
  (let* ((info (modinfo-section-contents file))
         (entries (concatenate
                   (filter-map (match-lambda
                                (('softdep . value)
                                 (parse-softdep value))
                                (_ #f))
                               (modinfo-section-contents file)))))
    (let-values (((pres posts)
                  (partition (match-lambda
                              (("pre" . _) #t)
                              (("post" . _) #f))
                             entries)))
      (values (map (match-lambda
                    ((_ . value) value))
                   pres)
              (map (match-lambda
                    ((_ . value) value))
                   posts)))))

(define (module-aliases file)
  "Return the list of aliases of module FILE."
  (let ((info (modinfo-section-contents file)))
    (filter-map (match-lambda
                 (('alias . value)
                  value)
                 (_ #f))
                (modinfo-section-contents file))))

(define dot-ko
  (cut string-append <> ".ko"))

(define (ensure-dot-ko name)
  "Return NAME with a '.ko' prefix appended, unless it already has it."
  (if (string-suffix? ".ko" name)
      name
      (dot-ko name)))

(define (normalize-module-name module)
  "Return the \"canonical\" name for MODULE, replacing hyphens with
underscores."
  ;; See 'modname_normalize' in libkmod.
  (string-map (lambda (chr)
                (case chr
                  ((#\-) #\_)
                  (else chr)))
              module))

(define (file-name->module-name file)
  "Return the module name corresponding to FILE, stripping the trailing '.ko'
and normalizing it."
  (normalize-module-name (basename file ".ko")))

(define (find-module-file directory module)
  "Lookup module NAME under DIRECTORY, 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.

Module names can differ from file names in interesting ways; for instance,
module names usually (always?) use underscores as the inter-word separator,
whereas file names often, but not always, use hyphens.  Examples:
\"usb-storage.ko\", \"serpent_generic.ko\"."
  (define names
    ;; List of possible file names.  XXX: It would of course be cleaner to
    ;; have a database that maps module names to file names and vice versa,
    ;; but everyone seems to be doing hacks like this one.  Oh well!
    (map ensure-dot-ko
         (delete-duplicates
          (list module
                (normalize-module-name module)
                (string-map (lambda (chr) ;converse of 'normalize-module-name'
                              (case chr
                                ((#\_) #\-)
                                (else chr)))
                            module)))))

  (match (find-files directory
                     (lambda (file stat)
                       (member (basename file) names)))
    ((file)
     file)
    (()
     (error "kernel module not found" module directory))
    ((_ ...)
     (error "several modules by that name" module directory))))

(define* (recursive-module-dependencies files
                                        #:key (lookup-module dot-ko))
  "Return the topologically-sorted list of file names of the modules depended
on by FILES, recursively.  File names of modules are determined by applying
LOOKUP-MODULE to the module name."
  (let loop ((files   files)
             (result  '())
             (visited vlist-null))
    (match files
      (()
       (delete-duplicates (reverse result)))
      ((head . tail)
       (let* ((visited? (vhash-assoc head visited))
              (deps     (if visited?
                            '()
                            (map lookup-module (module-dependencies head))))
              (visited  (if visited?
                            visited
                            (vhash-cons head #t visited))))
         (loop (append deps tail)
               (append result deps) visited))))))

(define %not-newline
  (char-set-complement (char-set #\newline)))

(define (modules-loaded)
  "Return the list of names of currently loaded Linux modules."
  (let* ((contents (call-with-input-file "/proc/modules"
                     get-string-all))
         (lines    (string-tokenize contents %not-newline)))
    (match (map string-tokenize lines)
      (((modules . _) ...)
       modules))))

(define (module-black-list)
  "Return the black list of modules that must not be loaded.  This black list
is specified using 'modprobe.blacklist=MODULE1,MODULE2,...' on the kernel
command line; it is honored by libkmod for users that pass
'KMOD_PROBE_APPLY_BLACKLIST', which includes 'modprobe --use-blacklist' and
udev."
  (define parameter
    "modprobe.blacklist=")

  (let ((command (call-with-input-file "/proc/cmdline"
                   get-string-all)))
    (append-map (lambda (arg)
                  (if (string-prefix? parameter arg)
                      (string-tokenize (string-drop arg (string-length parameter))
                                       %not-comma)
                      '()))
                (string-tokenize command))))

(define (module-loaded? module)
  "Return #t if MODULE is already loaded.  MODULE must be a Linux module name,
not a file name."
  (member module (modules-loaded)))

(define* (load-linux-module* file
                             #:key
                             (recursive? #t)
                             (lookup-module dot-ko)
                             (black-list (module-black-list)))
  "Load Linux module from FILE, the name of a '.ko' file; return true on
success, false otherwise.  When RECURSIVE? is true, load its dependencies
first (à la 'modprobe'.)  The actual files containing modules depended on are
obtained by calling LOOKUP-MODULE with the module name.  Modules whose name
appears in BLACK-LIST are not loaded."
  (define (black-listed? module)
    (let ((result (member module black-list)))
      (when result
        (format (current-module-debugging-port)
                "not loading module '~a' because it's black-listed~%"
                module))
      result))

  (define (load-dependencies file)
    (let ((dependencies (module-dependencies file)))
      (every (cut load-linux-module* <>
                  #:lookup-module lookup-module
                  #:black-list black-list)
             (map lookup-module dependencies))))

  (and (not (black-listed? (file-name->module-name file)))
       (or (not recursive?)
           (load-dependencies file))
       (let ((fd #f))
         (format (current-module-debugging-port)
                 "loading Linux module from '~a'...~%" file)

         (catch 'system-error
           (lambda ()
             (set! fd (open-fdes file O_RDONLY))
             (load-linux-module/fd fd)
             (close-fdes fd)
             #t)
           (lambda args
             ;; If this module was already loaded and we're in modprobe style, ignore
             ;; the error.
             (when fd (close-fdes fd))
             (or (and recursive? (= EEXIST (system-error-errno args)))
                 (apply throw args)))))))

(define (load-linux-modules-from-directory modules directory)
  "Load MODULES and their dependencies from DIRECTORY, a directory containing
the '.ko' files.  The '.ko' suffix is automatically added to MODULES if
needed."
  (define module-name->file-name
    (module-name-lookup directory))

  (for-each (lambda (module)
              (load-linux-module* (module-name->file-name module)
                                  #:lookup-module module-name->file-name))
            modules))


;;;
;;; Device modules.
;;;

;; Copied from (guix utils).  FIXME: Factorize.
(define (readlink* file)
  "Call 'readlink' until the result is not a symlink."
  (define %max-symlink-depth 50)

  (let loop ((file  file)
             (depth 0))
    (define (absolute target)
      (if (absolute-file-name? target)
          target
          (string-append (dirname file) "/" target)))

    (if (>= depth %max-symlink-depth)
        file
        (call-with-values
            (lambda ()
              (catch 'system-error
                (lambda ()
                  (values #t (readlink file)))
                (lambda args
                  (let ((errno (system-error-errno args)))
                    (if (or (= errno EINVAL))
                        (values #f file)
                        (apply throw args))))))
          (lambda (success? target)
            (if success?
                (loop (absolute target) (+ depth 1))
                file))))))

;; See 'major' and 'minor' in <sys/sysmacros.h>.

(define (stat->device-major st)
  (ash (logand #xfff00 (stat:rdev st)) -8))

(define (stat->device-minor st)
  (logand #xff (stat:rdev st)))

(define %not-slash
  (char-set-complement (char-set #\/)))

(define (read-uevent port)
  "Read a /sys 'uevent' file from PORT and return an alist where each car is a
key such as 'MAJOR or 'DEVTYPE and each cdr is the corresponding value."
  (let loop ((result '()))
    (match (read-line port)
      ((? eof-object?)
       (reverse result))
      (line
       (loop (cons (key=value->pair line) result))))))

(define (device-module-aliases device)
  "Return the list of module aliases required by DEVICE, a /dev file name, as
in this example:

  (device-module-aliases \"/dev/sda\")
  => (\"scsi:t-0x00\" \"pci:v00008086d00009D03sv0000103Csd000080FAbc01sc06i01\")

The modules corresponding to these aliases can then be found using
'matching-modules'."
  ;; The approach is adapted from
  ;; <https://unix.stackexchange.com/questions/97676/how-to-find-the-driver-module-associated-with-a-device-on-linux>.
  (let* ((st        (stat device))
         (type      (stat:type st))
         (major     (stat->device-major st))
         (minor     (stat->device-minor st))
         (sys-name  (string-append "/sys/dev/"
                                   (case type
                                     ((block-special) "block")
                                     ((char-special)  "char")
                                     (else (symbol->string type)))
                                   "/" (number->string major) ":"
                                   (number->string minor)))
         (directory (canonicalize-path (readlink* sys-name))))
    (let loop ((components (string-tokenize directory %not-slash))
               (aliases    '()))
      (match components
        (("sys" "devices" _)
         (reverse aliases))
        ((head ... _)
         (let ((uevent (string-append (string-join components "/" 'prefix)
                                      "/uevent")))
           (if (file-exists? uevent)
               (let ((props (call-with-input-file uevent read-uevent)))
                 (match (assq-ref props 'MODALIAS)
                   (#f    (loop head aliases))
                   (alias (loop head (cons alias aliases)))))
               (loop head aliases))))))))

(define (read-module-aliases port)
  "Read from PORT data in the Linux 'modules.alias' file format.  Return a
list of alias/module pairs where each alias is a glob pattern as like the
result of:

  (string->compiled-sglob \"scsi:t-0x01*\")

and each module is a module name like \"snd_hda_intel\"."
  (define (comment? str)
    (string-prefix? "#" str))

  (define (tokenize str)
    ;; Lines have the form "alias ALIAS MODULE", where ALIAS can contain
    ;; whitespace.  This is why we don't use 'string-tokenize'.
    (let* ((str   (string-trim-both str))
           (left  (string-index str #\space))
           (right (string-rindex str #\space)))
      (list (string-take str left)
            (string-trim-both (substring str left right))
            (string-trim-both (string-drop str right)))))

  (let loop ((aliases '()))
    (match (read-line port)
      ((? eof-object?)
       (reverse aliases))
      ((? comment?)
       (loop aliases))
      (line
       (match (tokenize line)
         (("alias" alias module)
          (loop (alist-cons (string->compiled-sglob alias) module
                            aliases)))
         (()                                      ;empty line
          (loop aliases)))))))

(define (current-kernel-directory)
  "Return the directory of the currently running Linux kernel."
  (string-append (or (getenv "LINUX_MODULE_DIRECTORY")
                     "/run/booted-system/kernel/lib/modules")
                 "/" (utsname:release (uname))))

(define (current-alias-file)
  "Return the absolute file name of the default 'modules.alias' file."
  (string-append (current-kernel-directory) "/modules.alias"))

(define* (known-module-aliases #:optional (alias-file (current-alias-file)))
  "Return the list of alias/module pairs read from ALIAS-FILE.  Each alias is
actually a pattern."
  (call-with-input-file alias-file read-module-aliases))

(define* (matching-modules alias
                           #:optional (known-aliases (known-module-aliases)))
  "Return the list of modules that match ALIAS according to KNOWN-ALIASES.
ALIAS is a string like \"scsi:t-0x00\" as returned by
'device-module-aliases'."
  (filter-map (match-lambda
                ((pattern . module)
                 (and (glob-match? pattern alias)
                      module)))
              known-aliases))

(define* (missing-modules device modules-provided)
  "Assuming MODULES-PROVIDED lists kernel modules that are already
provided--e.g., in the initrd, return the list of missing kernel modules that
are required to access DEVICE."
  (define aliases
    ;; Attempt to load 'modules.alias' from the current kernel, assuming we're
    ;; on Guix System, and assuming that corresponds to the kernel we'll be
    ;; installing.
    (known-module-aliases))

  (if aliases
      (let* ((modules  (delete-duplicates
                        (append-map (cut matching-modules <> aliases)
                                    (device-module-aliases device))))

             ;; Module names (not file names) are supposed to use underscores
             ;; instead of hyphens.  MODULES is a list of module names, whereas
             ;; LINUX-MODULES is file names without '.ko', so normalize them.
             (provided (map file-name->module-name modules-provided)))
        (remove (cut member <> provided) modules))
      '()))


;;;
;;; Module databases.
;;;

(define (module-name->file-name/guess directory name)
  "Guess the file name corresponding to NAME, a module name.  That doesn't
always work because sometimes underscores in NAME map to hyphens (e.g.,
\"input-leds.ko\"), sometimes not (e.g., \"mac_hid.ko\")."
  (string-append directory "/" (ensure-dot-ko name)))

(define (module-name-lookup directory)
  "Return a one argument procedure that takes a module name (e.g.,
\"input_leds\") and returns its absolute file name (e.g.,
\"/.../input-leds.ko\")."
  (catch 'system-error
    (lambda ()
      (define mapping
        (call-with-input-file (string-append directory "/modules.name")
          read))

      (lambda (name)
        (or (assoc-ref mapping name)
            (module-name->file-name/guess directory name))))
    (lambda args
      (if (= ENOENT (system-error-errno args))
          (cut module-name->file-name/guess directory <>)
          (apply throw args)))))

(define (write-module-name-database directory)
  "Write a database that maps \"module names\" as they appear in the relevant
ELF section of '.ko' files, to actual file names.  This format is
Guix-specific.  It aims to deal with inconsistent naming, in particular
hyphens vs. underscores."
  (define mapping
    (map (lambda (file)
           (match (module-formal-name file)
             (#f   (cons (basename file ".ko") file))
             (name (cons name file))))
         (find-files directory "\\.ko$")))

  (call-with-output-file (string-append directory "/modules.name")
    (lambda (port)
      (display ";; Module name to file name mapping.
;;
;; This format is Guix-specific; it is not supported by upstream Linux tools.
\n"
               port)
      (pretty-print mapping port))))

(define (write-module-alias-database directory)
  "Traverse the '.ko' files in DIRECTORY and create the corresponding
'modules.alias' file."
  (define aliases
    (map (lambda (file)
           (cons (file-name->module-name file) (module-aliases file)))
         (find-files directory "\\.ko$")))

  (call-with-output-file (string-append directory "/modules.alias")
    (lambda (port)
      (display "# Aliases extracted from modules themselves.\n" port)
      (for-each (match-lambda
                  ((module . aliases)
                   (for-each (lambda (alias)
                               (format port "alias ~a ~a\n" alias module))
                             aliases)))
                aliases))))

(define (aliases->device-tuple aliases)
  "Traverse ALIASES, a list of module aliases, and search for
\"char-major-M-N\", \"block-major-M-N\", or \"devname:\" aliases.  When they
are found, return a tuple (DEVNAME TYPE MAJOR MINOR), otherwise return #f."
  (define (char/block-major? alias)
    (or (string-prefix? "char-major-" alias)
        (string-prefix? "block-major-" alias)))

  (define (char/block-major->tuple alias)
    (match (string-tokenize alias %not-dash)
      ((type "major" (= string->number major) (= string->number minor))
       (list (match type
               ("char" "c")
               ("block" "b"))
             major minor))))

  (let* ((devname     (any (lambda (alias)
                             (and (string-prefix? "devname:" alias)
                                  (string-drop alias 8)))
                           aliases))
         (major/minor (match (find char/block-major? aliases)
                        (#f #f)
                        (str (char/block-major->tuple str)))))
    (and devname major/minor
         (cons devname major/minor))))

(define %not-dash
  (char-set-complement (char-set #\-)))

(define (write-module-device-database directory)
  "Traverse the '.ko' files in DIRECTORY and create the corresponding
'modules.devname' file.  This file contains information about modules that can
be loaded on-demand, such as file system modules."
  (define aliases
    (filter-map (lambda (file)
                  (match (aliases->device-tuple (module-aliases file))
                    (#f #f)
                    (tuple (cons (file-name->module-name file) tuple))))
                (find-files directory "\\.ko$")))

  (call-with-output-file (string-append directory "/modules.devname")
    (lambda (port)
      (display "# Device nodes to trigger on-demand module loading.\n" port)
      (for-each (match-lambda
                  ((module devname type major minor)
                   (format port "~a ~a ~a~a:~a~%"
                           module devname type major minor)))
                aliases))))

(define (depmod version directory)
  "Given an (existing) DIRECTORY, invoke depmod on it for
kernel version VERSION."
  (let ((destination-directory (string-append directory "/lib/modules/"
                                              version))
        ;; Note: "System.map" is an input file.
        (maps-file (string-append directory "/System.map"))
        ;; Note: "Module.symvers" is an input file.
        (symvers-file (string-append directory "/Module.symvers")))
    ;; These files will be regenerated by depmod below.
    (for-each (lambda (basename)
                (when (and (string-prefix? "modules." basename)
                           ;; Note: "modules.builtin" is an input file.
                           (not (string=? "modules.builtin" basename))
                           ;; Note: "modules.order" is an input file.
                           (not (string=? "modules.order" basename)))
                  (delete-file (string-append destination-directory "/"
                                              basename))))
              (scandir destination-directory))
    (invoke "depmod"
            "-e" ; Report symbols that aren't supplied
            ;"-w" ; Warn on duplicates
            "-b" directory
            "-F" maps-file
            ;"-E" symvers-file ; using both "-E" and "-F" is not possible.
            version)))

(define (make-linux-module-directory inputs version output)
  "Create a new directory OUTPUT and ensure that the directory
OUTPUT/lib/modules/VERSION can be used as a source of Linux
kernel modules for the first kmod in PATH now to eventually
load.  Take modules to put into OUTPUT from INPUTS.

Right now that means it creates @code{modules.*.bin} which
@command{modprobe} will use to find loadable modules."
  (union-build output inputs #:create-all-directories? #t)
  (depmod version output))

;;; linux-modules.scm ends here