libudev: allow to store negative values in the udev database

[elogind.git] / README

diff --git a/README b/README
index b4c0ee051faa4f014b6fb454ea7b999d2326b7db..664457de0f9b2f5cfe2dbfca2b07a15e22fa272c 100644 (file)
--- a/README
+++ b/README
@@ -8,11 +8,11 @@ recommend to replace a distro's udev installation with the upstream version.
 Tools and rules shipped by udev are not public API and may change at any time.
 Never call any private tool in /lib/udev from any external application, it might
 just go away in the next release. Access to udev information is only offered
 Tools and rules shipped by udev are not public API and may change at any time.
 Never call any private tool in /lib/udev from any external application, it might
 just go away in the next release. Access to udev information is only offered

-by udevadm and libudev. Tools and rules in /lib/udev and the entire content of
-/dev/.udev/ is private to udev.
+by udevadm and libudev. Tools and rules in /lib/udev, and the entire content of
+the /dev/.udev directory is private to udev and does change whenever needed.

 
 Requirements:
 
 Requirements:

-  - Version 2.6.25 of the Linux kernel with sysfs, procfs, signalfd, inotify,
+  - Version 2.6.27 of the Linux kernel with sysfs, procfs, signalfd, inotify,

     unix domain sockets, networking and hotplug enabled:
       CONFIG_HOTPLUG=y
       CONFIG_UEVENT_HELPER_PATH=""
     unix domain sockets, networking and hotplug enabled:
       CONFIG_HOTPLUG=y
       CONFIG_UEVENT_HELPER_PATH=""


@@ -22,18 +22,19 @@ Requirements:
       CONFIG_SYSFS_DEPRECATED*=n
       CONFIG_PROC_FS=y
       CONFIG_TMPFS=y
       CONFIG_SYSFS_DEPRECATED*=n
       CONFIG_PROC_FS=y
       CONFIG_TMPFS=y

-      CONFIG_TMPFS_POSIX_ACL=y
-      CONFIG_INOTIFY=y
+      CONFIG_INOTIFY_USER=y

       CONFIG_SIGNALFD=y
       CONFIG_SIGNALFD=y

+      CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes)
+      CONFIG_BLK_DEV_BSG=y (SCSI devices)

 
 

-  - For reliable operation, the kernel must not use the CONFIG_SYSFS_DEPRECATED*
+  - For reliable operations, the kernel must not use the CONFIG_SYSFS_DEPRECATED*

     option.
 
     option.
 

-  - Unix domain sockets (CONFIG_UNIX) as a loadable kernel module is not
-    supported.
+  - Unix domain sockets (CONFIG_UNIX) as a loadable kernel module may work,
+    but it is not supported.

 
 

-  - The proc filesystem must be mounted on /proc/, the sysfs filesystem must
-    be mounted at /sys/. No other locations are supported by udev.
+  - The proc filesystem must be mounted on /proc, the sysfs filesystem must
+    be mounted at /sys. No other locations are supported by udev.

 
   - The system must have the following group names resolvable at udev startup:
       disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.
 
   - The system must have the following group names resolvable at udev startup:
       disk, cdrom, floppy, tape, audio, video, lp, tty, dialout, kmem.


@@ -46,29 +47,30 @@ Requirements:
     --disable-extras option.
 
 Operation:
     --disable-extras option.
 
 Operation:

-  Udev creates and removes device nodes in /dev/, based on events the kernel
+  Udev creates and removes device nodes in /dev, based on events the kernel

   sends out on device discovery or removal.
 
   sends out on device discovery or removal.
 

-  - Early in the boot process, the /dev/ directory should get a 'tmpfs'
+  - Early in the boot process, the /dev directory should get a 'tmpfs'

     filesystem mounted, which is maintained by udev. Created nodes or changed
     permissions will not survive a reboot, which is intentional.
 
     filesystem mounted, which is maintained by udev. Created nodes or changed
     permissions will not survive a reboot, which is intentional.
 

-  - The content of /lib/udev/devices/ directory which contains the nodes,
+  - The content of /lib/udev/devices directory which contains the nodes,

     symlinks and directories, which are always expected to be in /dev, should
     be copied over to the tmpfs mounted /dev, to provide the required nodes
     to initialize udev and continue booting.
 
     symlinks and directories, which are always expected to be in /dev, should
     be copied over to the tmpfs mounted /dev, to provide the required nodes
     to initialize udev and continue booting.
 

-  - The old hotplug helper /sbin/hotplug should be disabled in the kernel
-    configuration, it is not needed, and may render the system unusable
-    because of a fork-bombing behavior.
+  - The deprecated hotplug helper /sbin/hotplug should be disabled in the
+    kernel configuration, it is not needed today, and may render the system
+    unusable because the kernel may create too many processes in parallel
+    so that the system runs out-of-memory.

 
   - All kernel events are matched against a set of specified rules in
 
   - All kernel events are matched against a set of specified rules in

-    /lib/udev/rules.d/ which make it possible to hook into the event
+    /lib/udev/rules.d which make it possible to hook into the event

     processing to load required kernel modules and setup devices. For all
     devices the kernel exports a major/minor number, udev will create a
     device node with the default kernel name, or the one specified by a
     matching udev rule.
 
     processing to load required kernel modules and setup devices. For all
     devices the kernel exports a major/minor number, udev will create a
     device node with the default kernel name, or the one specified by a
     matching udev rule.
 

-Please direct any comment/question/concern to the linux-hotplug mailing list at:
+Please direct any comment/question to the linux-hotplug mailing list at:

   linux-hotplug@vger.kernel.org
 
   linux-hotplug@vger.kernel.org