linux-boot: Mount /dev as a devtmpfs from the start.

Suggested by Petter <petter@mykolab.ch>
and Mark H Weaver <mhw@netris.org>.
Reported by Duncan Keall <duncan@duncankeall.com>.

Partly fixes <http://bugs.gnu.org/19190> by populating /dev/mapper
early enough.

* gnu/build/linux-boot.scm (mount-essential-file-systems): Mount /dev as
  a devtmpfs.
  (move-essential-file-systems): Add /dev.
  (mount-root-file-system): Mount /rw-root/dev as a devtmpfs instead of
  calling 'make-essential-device-nodes'.
  (boot-system): Remove call to 'make-essential-device-nodes'.
* gnu/system/file-systems.scm (%devtmpfs-file-system): Remove.
* doc/guix.texi (File Systems): Adjust accordingly.

1 files changed, 9 insertions, 11 deletions

diff --git a/gnu/build/linux-boot.scm b/gnu/build/linux-boot.scm
index 3081a93a97..30d6570b04 100644
--- a/gnu/build/linux-boot.scm
+++ b/gnu/build/linux-boot.scm
@@ -48,7 +48,7 @@
 ;;; Code:
 
 (define* (mount-essential-file-systems #:key (root "/"))
-  "Mount /proc and /sys under ROOT."
+  "Mount /dev, /proc, and /sys under ROOT."
   (define (scope dir)
     (string-append root
                    (if (string-suffix? "/" root)
@@ -60,6 +60,10 @@
     (mkdir (scope "proc")))
   (mount "none" (scope "proc") "proc")
 
+  (unless (file-exists? (scope "dev"))
+    (mkdir (scope "dev")))
+  (mount "none" (scope "dev") "devtmpfs")
+
   (unless (file-exists? (scope "sys"))
     (mkdir (scope "sys")))
   (mount "none" (scope "sys") "sysfs"))
@@ -71,7 +75,7 @@
                 (unless (file-exists? target)
                   (mkdir target))
                 (mount dir target "" MS_MOVE)))
-            '("/proc" "/sys")))
+            '("/dev" "/proc" "/sys")))
 
 (define (linux-command-line)
   "Return the Linux kernel command line as a list of strings."
@@ -100,7 +104,7 @@ with the given MAJOR number, starting with MINOR."
 
 (define* (make-essential-device-nodes #:key (root "/"))
   "Make essential device nodes under ROOT/dev."
-  ;; The hand-made udev!
+  ;; The hand-made devtmpfs/udev!
 
   (define (scope dir)
     (string-append root
@@ -255,7 +259,8 @@ UNIONFS."
         (mount "none" "/rw-root" "tmpfs")
 
         ;; We want read-write /dev nodes.
-        (make-essential-device-nodes #:root "/rw-root")
+        (mkdir-p "/rw-root/dev")
+        (mount "none" "/rw-root/dev" "devtmpfs")
 
         ;; Make /root a union of the tmpfs and the actual root.  Use
         ;; 'max_files' to set a high RLIMIT_NOFILE for the unionfs process
@@ -385,9 +390,6 @@ to it are lost."
          (unless (configure-qemu-networking)
            (display "network interface is DOWN\n")))
 
-       ;; Make /dev nodes.
-       (make-essential-device-nodes)
-
        ;; Prepare the real root file system under /root.
        (unless (file-exists? "/root")
          (mkdir "/root"))
@@ -405,10 +407,6 @@ to it are lost."
                                    #:volatile-root? volatile-root?)
            (mount "none" "/root" "tmpfs"))
 
-       (unless (file-exists? "/root/dev")
-         (mkdir "/root/dev")
-         (make-essential-device-nodes #:root "/root"))
-
        ;; Mount the specified file systems.
        (for-each mount-file-system
                  (remove root-mount-point? mounts))