patch-2.4.10 linux/Documentation/filesystems/devfs/README

• Lines: 221
• Date: Fri Sep 21 10:55:22 2001
• Orig file: v2.4.9/linux/Documentation/filesystems/devfs/README
• Orig date: Tue Jul 3 17:08:18 2001

diff -u --recursive --new-file v2.4.9/linux/Documentation/filesystems/devfs/README linux/Documentation/filesystems/devfs/README
@@ -3,7 +3,7 @@
 
 Linux Devfs (Device File System) FAQ
 Richard Gooch
-26-APR-2001
+23-AUG-2001
 
 -----------------------------------------------------------------------------
 
@@ -18,17 +18,14 @@
 
 http://www.atnf.csiro.au/~rgooch/linux/
 
-NEWSFLASH: The official 2.3.46 kernel has
-included the devfs patch. Future patches will be released which
-build on this. These patches are rolled into Linus' tree from time to
-time.
-
 A mailing list is available which you may subscribe to. Send
 email
 to majordomo@oss.sgi.com with the following line in the
 body of the message:
 subscribe devfs
-The list is archived at
+To unsubscribe, send the message body:
+unsubscribe devfs
+instead. The list is archived at
 
 http://oss.sgi.com/projects/devfs/archive/.
 
@@ -71,6 +68,8 @@
 
 Other resources
 
+Translations of this document
+
 
 -----------------------------------------------------------------------------
 
@@ -82,7 +81,7 @@
 name rather than major and minor numbers. These devices will appear in
 devfs automatically, with whatever default ownership and
 protection the driver specified. A daemon (devfsd) can be used to
-override these defaults.
+override these defaults. Devfs has been in the kernel since 2.3.46.
 
 NOTE that devfs is entirely optional. If you prefer the old
 disc-based device nodes, then simply leave CONFIG_DEVFS_FS=n (the
@@ -604,6 +603,20 @@
 has problems with symbolic links. Append the following lines to your
 /etc/securetty file:
 
+vc/1
+vc/2
+vc/3
+vc/4
+vc/5
+vc/6
+vc/7
+vc/8
+
+This will not weaken security. If you have a version of util-linux
+earlier than 2.10.h, please upgrade to 2.10.h or later. If you
+absolutely cannot upgrade, then also append the following lines to
+your /etc/securetty file:
+
 1
 2
 3
@@ -618,27 +631,13 @@
 are problems with dealing with symlinks, I'm suspicious of the level
 of security offered in any case.
 
-A better solution is to install util-linux-2.10.h or later, which
-fixes a bug with ttyname handling in the login programme. Then append
-the following lines to your /etc/securetty file:
-
-vc/1
-vc/2
-vc/3
-vc/4
-vc/5
-vc/6
-vc/7
-vc/8
-
-This will not weaken security.
-
 XFree86
 While not essential, it's probably a good idea to upgrade to XFree86
 4.0, as patches went in to make it more devfs-friendly. If you don't,
 you'll probably need to apply the following patch to
 /etc/security/console.perms so that ordinary users can run
-startx.
+startx. Note that not all distributions have this file (e.g. Debian),
+so if it's not present, don't worry about it.
 
 --- /etc/security/console.perms.orig    Sat Apr 17 16:26:47 1999 
 +++ /etc/security/console.perms Fri Feb 25 23:53:55 2000 
@@ -691,9 +690,12 @@
 described above.
 
 The Kernel
-Finally, you need to make sure devfs is compiled into your
-kernel. Set CONFIG_DEVFS_FS=y and CONFIG_DEVFS_MOUNT=y and recompile
-your kernel. At boot, devfs will be mounted onto /dev.
+Finally, you need to make sure devfs is compiled into your kernel. Set
+CONFIG_EXPERIMENTAL=y, CONFIG_DEVFS_FS=y and CONFIG_DEVFS_MOUNT=y by
+using favourite configuration tool (i.e. make config or
+make xconfig) and then make dep; make clean and then
+recompile your kernel and modules. At boot, devfs will be mounted onto
+/dev.
 
 If you encounter problems booting (for example if you forgot a
 configuration step), you can pass devfs=nomount at the kernel
@@ -805,8 +807,17 @@
 directory to store the database. The sample /etc/devfsd.conf
 file above may still be used. You will need to create the
 /dev-state directory prior to installing devfsd. If you have
-old permissions in /dev, then just copy the device nodes over
-to the new directory.
+old permissions in /dev, then just copy (or move) the device
+nodes over to the new directory.
+
+Which method is better?
+
+The best method is to have the permissions database stored in the
+mounted-over /dev. This is because you will not need to copy
+device nodes over to /dev-state, and because it allows you to
+switch between devfs and non-devfs kernels, without requiring you to
+copy permissions between /dev-state (for devfs) and
+/dev (for non-devfs).
 
 
 Dealing with drivers without devfs support
@@ -1038,6 +1049,13 @@
 directory tree that reflects the topology of available devices. The
 topological tree is useful for finding how your devices are arranged.
 
+Below is a list of the naming schemes for the most common drivers. A
+list of reserved device names is
+available for reference. Please send email to
+rgooch@atnf.csiro.au to obtain an allocation. Please be
+patient (the maintainer is busy). An alternative name may be allocated
+instead of the requested name, at the discretion of the maintainer.
+
 Disc Devices
 
 All discs, whether SCSI, IDE or whatever, are placed under the
@@ -1486,6 +1504,47 @@
 namespace, but have had no response.
 
 
+How can I test if I have devfs compiled into my kernel?
+
+All filesystems built-in or currently loaded are listed in
+/proc/filesystems. If you see a devfs entry, then
+you know that devfs was compiled into your kernel. If you have
+correctly configured and rebuilt your kernel, then devfs will be
+built-in. If you think you've configured it in, but
+/proc/filesystems doesn't show it, you've made a mistake.
+Common mistakes include:
+
+Using a 2.2.x kernel without applying the devfs patch (if you
+don't know how to patch your kernel, use 2.4.x instead, don't bother
+asking me how to patch)
+Forgetting to set CONFIG_EXPERIMENTAL=y
+Forgetting to set CONFIG_DEVFS_FS=y
+Forgetting to set CONFIG_DEVFS_MOUNT=y (if you want devfs
+to be automatically mounted at boot)
+Editing your .config manually, instead of using make
+config or make xconfig
+Forgetting to run make dep; make clean after changing the
+configuration and before compiling
+Forgetting to compile your kernel and modules
+Forgetting to install your kernel
+Forgetting to install your modules
+
+Please check twice that you've done all these steps before sending in
+a bug report.
+
+
+
+How can I test if devfs is mounted on /dev?
+
+The device filesystem will always create an entry called
+".devfsd", which is used to communicate with the daemon. Even
+if the daemon is not running, this entry will exist. Testing for the
+existence of this entry is the approved method of determining if devfs
+is mounted or not. Note that the type of entry (i.e. regular file,
+character device, named pipe, etc.) may change without notice. Only
+the existence of the entry should be relied upon.
+
+
 
 
 
@@ -1713,6 +1772,23 @@
 
 2nd Annual Storage Management Workshop held in Miamia, Florida,
 U.S.A. in October 2000.
+
+
+
+
+-----------------------------------------------------------------------------
+
+
+Translations of this document
+
+This document has been translated into other languages.
+
+
+
+
+A Korean translation by viatoris@nownuri.net is available at
+
+http://home.nownuri.net/~viatoris/devfs/devfs.html