system: Tell module-init-tools where to look for modules.

* gnu/packages/linux.scm (module-init-tools)[source](patches): New
  field.
* gnu/packages/patches/module-init-tools-moduledir.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/system.scm (etc-directory): Add #:kernel parameter.  Set
  'LINUX_MODULE_DIRECTORY' in bashrc.
  (operating-system-etc-directory): Pass #:kernel to 'etc-directory'.

3 files changed, 179 insertions, 2 deletions

diff --git a/gnu/packages/linux.scm b/gnu/packages/linux.scm
index 46f2178488b..518b0e41b9f 100644
--- a/gnu/packages/linux.scm
+++ b/gnu/packages/linux.scm
@@ -133,7 +133,9 @@
                    version ".tar.bz2"))
              (sha256
               (base32
-               "0jxnz9ahfic79rp93l5wxcbgh4pkv85mwnjlbv1gz3jawv5cvwp1"))))
+               "0jxnz9ahfic79rp93l5wxcbgh4pkv85mwnjlbv1gz3jawv5cvwp1"))
+             (patches
+              (list (search-patch "module-init-tools-moduledir.patch")))))
     (build-system gnu-build-system)
     (arguments
      ;; FIXME: The upstream tarball lacks man pages, and building them would
diff --git a/gnu/packages/patches/module-init-tools-moduledir.patch b/gnu/packages/patches/module-init-tools-moduledir.patch
new file mode 100644
index 00000000000..68d7988f532
--- /dev/null
+++ b/gnu/packages/patches/module-init-tools-moduledir.patch
@@ -0,0 +1,168 @@
+This patch changes 'modprobe' & co. so they honor the 'LINUX_MODULE_DIRECTORY'
+environment variable, rather than looking for modules exclusively in
+/lib/modules.
+
+Patch by David Guibert, from Nixpkgs; adjusted to use 'LINUX_MODULE_DIRECTORY'
+rather than 'MODULE_DIR' as the variable name.
+
+commit cf2c95edb7918bc658f6cae93793c1949fc9cb6e
+Author: David Guibert <david.guibert@gmail.com>
+Date:   Fri Aug 5 14:20:12 2011 +0200
+
+    introduce module-dir
+
+diff --git a/depmod.c b/depmod.c
+index a1d2f8c..9362a35 100644
+--- a/depmod.c
++++ b/depmod.c
+@@ -48,9 +48,6 @@
+ 
+ #include "testing.h"
+ 
+-#ifndef MODULE_DIR
+-#define MODULE_DIR "/lib/modules/"
+-#endif
+ 
+ #ifndef MODULE_BUILTIN_KEY
+ #define MODULE_BUILTIN_KEY "built-in"
+@@ -1516,6 +1513,7 @@ static int parse_config_file(const char *filename,
+        char *line;
+        unsigned int linenum = 0;
+        FILE *cfile;
++       char *module_dir;
+ 
+        cfile = fopen(filename, "r");
+        if (!cfile) {
+@@ -1525,6 +1523,10 @@ static int parse_config_file(const char *filename,
+                return 0;
+        }
+ 
++        if((module_dir = getenv("LINUX_MODULE_DIRECTORY")) == NULL) {
++                module_dir = "/lib/modules/";
++        }
++
+        while ((line = getline_wrapped(cfile, &linenum)) != NULL) {
+                char *ptr = line;
+                char *cmd, *modname;
+@@ -1550,7 +1552,7 @@ static int parse_config_file(const char *filename,
+                                        continue;
+                                }
+                                nofail_asprintf(&dirname, "%s%s%s/%s", basedir,
+-                                       MODULE_DIR, kernelversion, search_path);
++                                       module_dir, kernelversion, search_path);
+                                len = strlen(dirname);
+                                *search = add_search(dirname, len, *search);
+                                free(dirname);
+@@ -1565,7 +1567,7 @@ static int parse_config_file(const char *filename,
+                                continue;
+ 
+                        nofail_asprintf(&pathname, "%s%s%s/%s/%s.ko", basedir,
+-                               MODULE_DIR, kernelversion, subdir, modname);
++                               module_dir, kernelversion, subdir, modname);
+ 
+                        *overrides = add_override(pathname, *overrides);
+                        free(pathname);
+@@ -1737,6 +1739,7 @@ int main(int argc, char *argv[])
+        char *basedir = "", *dirname, *version;
+        char *system_map = NULL, *module_symvers = NULL;
+        int i;
++       char *module_dir;
+        const char *config = NULL;
+ 
+        if (native_endianness() == 0)
+@@ -1832,7 +1835,11 @@ int main(int argc, char *argv[])
+        if (optind == argc)
+                all = 1;
+ 
+-       nofail_asprintf(&dirname, "%s%s%s", basedir, MODULE_DIR, version);
++        if((module_dir = getenv("LINUX_MODULE_DIRECTORY")) == NULL) {
++                module_dir = "/lib/modules/";
++        }
++
++       nofail_asprintf(&dirname, "%s%s%s", basedir, module_dir, version);
+ 
+        if (maybe_all) {
+                if (!doing_stdout && !depfile_out_of_date(dirname))
+@@ -1850,7 +1857,7 @@ int main(int argc, char *argv[])
+                size_t len;
+ 
+                nofail_asprintf(&dirname, "%s%s%s/updates", basedir,
+-                               MODULE_DIR, version);
++                               module_dir, version);
+                len = strlen(dirname);
+                search = add_search(dirname, len, search);
+        }
+diff --git a/modinfo.c b/modinfo.c
+index 1dd8469..67b1041 100644
+--- a/modinfo.c
++++ b/modinfo.c
+@@ -19,9 +19,6 @@
+ #include "zlibsupport.h"
+ #include "testing.h"
+ 
+-#ifndef MODULE_DIR
+-#define MODULE_DIR "/lib/modules"
+-#endif
+ 
+ struct param
+ {
+@@ -193,6 +190,11 @@ static struct elf_file *grab_module(const char *name,
+        struct utsname buf;
+        char *depname, *p, *moddir;
+        struct elf_file *module;
++       char *module_dir;
++
++        if((module_dir = getenv("LINUX_MODULE_DIRECTORY")) == NULL) {
++                module_dir = "/lib/modules/";
++        }
+ 
+        if (strchr(name, '.') || strchr(name, '/')) {
+                module = grab_elf_file(name);
+@@ -207,9 +209,9 @@ static struct elf_file *grab_module(const char *name,
+                kernel = buf.release;
+        }
+        if (strlen(basedir))
+-               nofail_asprintf(&moddir, "%s/%s/%s", basedir, MODULE_DIR, kernel);
++               nofail_asprintf(&moddir, "%s/%s/%s", basedir, module_dir, kernel);
+        else
+-               nofail_asprintf(&moddir, "%s/%s", MODULE_DIR, kernel);
++               nofail_asprintf(&moddir, "%s/%s", module_dir, kernel);
+ 
+        /* Search for it in modules.dep. */
+        nofail_asprintf(&depname, "%s/%s", moddir, "modules.dep");
+diff --git a/modprobe.c b/modprobe.c
+index 5464f45..d9fbf9d 100644
+--- a/modprobe.c
++++ b/modprobe.c
+@@ -86,10 +86,6 @@ typedef enum
+ 
+ } modprobe_flags_t;
+ 
+-#ifndef MODULE_DIR
+-#define MODULE_DIR "/lib/modules"
+-#endif
+-
+ /**
+  * print_usage - output the prefered program usage
+  *
+@@ -2136,6 +2132,7 @@ int main(int argc, char *argv[])
+        struct modprobe_conf conf = {};
+ 
+        recursion_depth = 0;
++       char *module_dir = NULL;
+ 
+        /* Prepend options from environment. */
+        argv = merge_args(getenv("MODPROBE_OPTIONS"), argv, &argc);
+@@ -2233,7 +2230,11 @@ int main(int argc, char *argv[])
+        if (argc < optind + 1 && !dump_config && !list_only)
+                print_usage(argv[0]);
+ 
+-       nofail_asprintf(&dirname, "%s%s/%s", basedir, MODULE_DIR, buf.release);
++       if((module_dir = getenv("LINUX_MODULE_DIRECTORY")) == NULL) {
++               module_dir = "/lib/modules";
++       }
++
++       nofail_asprintf(&dirname, "%s%s/%s", basedir, module_dir, buf.release);
+ 
+        /* Old-style -t xxx wildcard?  Only with -l. */
+        if (list_only) {
diff --git a/gnu/system.scm b/gnu/system.scm
index a224916c0d8..4dc6ebd5a72 100644
--- a/gnu/system.scm
+++ b/gnu/system.scm
@@ -229,6 +229,7 @@ explicitly appear in OS."
 This is the GNU system.  Welcome.\n")
 
 (define* (etc-directory #:key
+                        kernel
                         (locale "C") (timezone "Europe/Paris")
                         (issue "Hello!\n")
                         (skeletons '())
@@ -255,6 +256,11 @@ export LC_ALL=\"" locale "\"
 export TZ=\"" timezone "\"
 export TZDIR=\"" tzdata "/share/zoneinfo\"
 
+# Tell 'modprobe' & co. where to look for modules.
+# XXX: The downside of doing it here is that when switching to a new config
+# without rebooting, this variable possibly becomes invalid.
+export LINUX_MODULE_DIRECTORY=" kernel "/lib/modules
+
 export PATH=$HOME/.guix-profile/bin:/run/current-system/profile/bin
 export PATH=/run/setuid-programs:/run/current-system/profile/sbin:$PATH
 export CPATH=$HOME/.guix-profile/include:" profile "/include
@@ -317,7 +323,8 @@ alias ll='ls -l'
                               (append-map service-pam-services services))))
        (profile-drv (operating-system-profile os))
        (skeletons   (operating-system-skeletons os)))
-   (etc-directory #:pam-services pam-services
+   (etc-directory #:kernel (operating-system-kernel os)
+                  #:pam-services pam-services
                   #:skeletons skeletons
                   #:issue (operating-system-issue os)
                   #:locale (operating-system-locale os)