X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=README;h=0cd868ade28b70e40163bbb3ddfca44f0e536b8c;hp=54cee659a833206953dc521f7ff8f59d4996a673;hb=cac2e345596b2743053c0285280b81794b3aaf10;hpb=e5e322bc627a07d29a07e08f7c96bd644a3ae057 diff --git a/README b/README index 54cee659a..0cd868ade 100644 --- a/README +++ b/README @@ -1,94 +1,183 @@ +Elogind User, Seat and Session Manager -udev - a userspace implementation of devfs - -For more information on the design, and structure of this project, see the -files in the docs/ directory. - -To use: - -- You must be running a 2.6 version of the Linux kernel. - -- Your 2.6 kernel must have had CONFIG_HOTPLUG enabled when it was built. - -- Make sure sysfs is mounted. udev will figure out where sysfs is mounted, but - the traditional place for it is at /sys. You can mount it by hand by running: - mount -t sysfs none /sys - -- Make sure you have the latest version of the linux-hotplug scripts. They are - available at linux-hotplug.sf.net or from your local kernel.org mirror at: - kernel.org/pub/linux/utils/kernel/hotplug/ - They are required in order for udev to work properly. - - If for some reason you do not install the hotplug scripts, you must tell the - kernel to point the hotplug binary at wherever you install udev at. This can - be done by: - echo "/sbin/udev" > /proc/sys/kernel/hotplug - -- Build the project: - make - - Note: - There are a number of different flags that you can use when building - udev. They are as follows: - prefix - set this to the default root that you want udev to be - installed into. This works just like the 'configure --prefix' - script does. Default value is ''. Only override this if you - really know what you are doing. - USE_KLIBC - if set to 'true', udev is built and linked against the - included version of klibc. Default value is 'false'. - USE_LOG - if set to 'true', udev will emit messages to the syslog when - it creates or removes device nodes. This is helpful to see - what udev is doing. This is enabled by default. Note, if you - are building udev against klibc it is recommended that you - disable this option (due to klibc's syslog implementation.) - USE_SELINUX - if set to 'true', udev will be built with SELinux support - enabled. This is disabled by default. - DEBUG - if set to 'true', debugging messages will be sent to the syslog - as udev is run. Default value is 'false'. - KERNEL_DIR - If this is not set it will default to /lib/modules/`uname -r`/build - This is used if USE_KLIBC=true to find the kernel include - directory that klibc needs to build against. This must be set - if you are not building udev while running a 2.6 kernel. - - So, if you want to build udev using klibc with debugging messages, you - would do: - make USE_KLIBC=true DEBUG=true - -- Install the project: - make install - - This will put the udev binary in /sbin, create the /udev and /etc/udev - directories, and place the udev configuration files in /etc/udev. You - will probably want to edit the *.rules files to create custom naming - rules. More info on how the config files are set up are contained in - comments in the files, and is located in the documentation. - -- Add and remove devices from the system and marvel as nodes are created - and removed in /udev/ based on the device types. - -- If you later get sick of it, uninstall it: - make uninstall - - -Things are still quite rough, but it should work properly. If nothing -seems to happen, make sure your build worked properly by running the -udev-test.pl script as root in the test/ subdirectory of the udev source -tree. - -Development and documentation help is very much appreciated, see the TODO -file for a list of things left to be done. - - -Any comment/questions/concerns please let me and the other udev developers -know by sending a message to the linux-hotplug-devel mailing list at: - linux-hotplug-devel@lists.sourceforge.net - -greg k-h -greg@kroah.com +Introduction +------------ +Elogind is the systemd project's "logind", extracted out to be a +standalone daemon. It integrates with PAM to know the set of users +that are logged in to a system and whether they are logged in +graphically, on the console, or remotely. Elogind exposes this +information via the standard org.freedesktop.login1 D-Bus interface, +as well as through the file system using systemd's standard +/run/systemd layout. Elogind also provides "libelogind", which is a +subset of the facilities offered by "libsystemd". There is a +"libelogind.pc" pkg-config file as well. + +All of the credit for elogind should go to the systemd developers. +For more on systemd, see +http://www.freedesktop.org/wiki/Software/systemd. All of the blame +should go to Andy Wingo, who extracted elogind from systemd. + +Contributing +------------ + +Elogind was branched from systemd version 219, and preserves the git +history of the systemd project. The version of elogind is the +upstream systemd version, followed by the patchlevel of elogind. For +example version 219.12 is the twelfth elogind release, which aims to +provide a subset of the interfaces of systemd 219. + +To contribute to elogind, fork the current source code from github: + + https://github.com/elogind/elogind + +Send a pull request for the changes you like. + +To chat about elogind: + + #guix on irc.freenode.org + +Finally, bug reports: + + https://github.com/elogind/elogind/issues + +Why bother? +----------- + +Elogind has been developed for use in GuixSD, the OS distribution of +GNU Guix. See http://gnu.org/s/guix for more on Guix. GuixSD uses a +specific init manager (DMD), for reasons that are not relevant here, +but still aims to eventually be a full-featured distribution that can +run GNOME and other desktop environments. However, to run GNOME these +days means that you need to have support for the login1 D-Bus +interface, which is currently only provided by systemd. That is the +origin of this project: to take the excellent logind functionality +from systemd and provide it as a standalone package. + +We like systemd. We realize that there are people out there that hate +it. You're welcome to use elogind for whatever purpose you like -- +as-is, or as a jumping-off point for other things -- but please don't +use it as part of some anti-systemd vendetta. Systemd hackers are +smart folks that are trying to solve interesting problems on the free +desktop, and their large adoption is largely because they solve +problems that users and developers of user-focused applications care +about. We are appreciative of their logind effort and think that +everyone deserves to run it if they like, even if they use a different +PID 1. + +Differences relative to systemd +------------------------------- + +The pkg-config file is called libelogind, not libsystemd or +libsystemd-logind. + +The headers are in , so like instead +of . + +Libelogind just implements login-related functionality. It also +provides the sd-bus API. + +Unlike systemd, whose logind arranges to manage resources for user +sessions via RPC calls to systemd, in elogind there is no systemd so +there is no global cgroup-based resource management. This has a few +implications: + + * Elogind does not create "slices" for users. Elogind will not + record that users are associated with slices. + + * The /run/systemd/slices directory will always be empty. + + * Elogind does not have the concept of a "scope", internally, as + it's the same as a session. Any API that refers to scopes will + always return an error code. + +On the other hand, elogind does use a similar strategy to systemd in +that it places processes in a private cgroup for organizational +purposes, without installing any controllers (see +http://0pointer.de/blog/projects/cgroups-vs-cgroups.html). This +allows elogind to map arbitrary processes to sessions, even if the +process does the usual double-fork to be reparented to PID 1. + +Elogind does not manage virtual terminals. + +Elogind does monitor power button and the lid switch, like systemd, +but instead of doing RPC to systemd to suspend, poweroff, or restart +the machine, elogind just does this directly. For suspend, hibernate, +and hybrid-sleep, elogind uses the same code as systemd-sleep. +Instead of using a separate sleep.conf file to configure the sleep +behavior, this is included in the [Sleep] section of +/etc/elogind/login.conf. See the example login.conf for more. For +shutdown, reboot, and kexec, elogind shells out to "halt", "reboot", +and "kexec" binaries. + +The loginctl command has the poweroff, reboot, sleep, hibernate, and +hybrid-sleep commands from systemd, as well as the --ignore-inhibitors +flag. + +The PAM module is called pam_elogind.so, not pam_systemd.so. + +Elogind and the running cgroup controller +----------------------------------------- +While 'configure' runs, it will detect which controller is in place. +If no controller is in place, configure will determine, that elogind +should be its own controller, which will be a very limited one. + +This approach should generally work, but if you just have no cgroup +controller in place, yet, or if you are currently switching to +another one, this approach will fail. + +In this case you can do one of the two following things: + + 1) Boot your system with the target init system and cgroup + controller, before configuring and building elogind, or + 2) Use the --with-cgroup-controller=name option. + +Example: If you plan to use openrc, but openrc has not yet booted + the machine, you can use + --with-cgroup-controller=openrc + to let elogind know that openrc will be the controller + in charge. + +However, if you set the controller at configure time to something +different than what is in place, elogind will not start until that +controller is actively used as the primary controller. + +License +------- + +LGPLv2.1+ for all code + + - except src/shared/MurmurHash2.c which is Public Domain + - except src/shared/siphash24.c which is CC0 Public Domain + - except src/journal/lookup3.c which is Public Domain + +Dependencies +------------ + + glibc >= 2.14 + libcap + libmount >= 2.20 (from util-linux) + libseccomp >= 1.0.0 (optional) + libblkid >= 2.24 (from util-linux) (optional) + PAM >= 1.1.2 (optional) + libacl (optional) + libselinux (optional) + make, gcc, and similar tools + +During runtime, you need the following additional dependencies: + + dbus >= 1.4.0 (strictly speaking optional, but recommended) + PolicyKit (optional) + +When building from git, you need the following additional +dependencies: + + pkg-config + docbook-xsl + xsltproc + automake + autoconf + libtool + intltool + gperf + gtkdocize (optional)