X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=README;h=80e1ab9dcc0f6fb2ed48e26355e38ba937cb492f;hp=2467b1e03ef30c9547e89d50b3f6b90712d751be;hb=33928c053afd0e119828fb52a20979da415c425d;hpb=5430f7f2bc7330f3088b894166bf3524a067e3d8 diff --git a/README b/README index 2467b1e03..80e1ab9dc 100644 --- a/README +++ b/README @@ -1,108 +1,157 @@ -systemd System and Service Manager - -DETAILS: - http://0pointer.de/blog/projects/systemd.html - -WEB SITE: - http://www.freedesktop.org/wiki/Software/systemd - -GIT: - git://anongit.freedesktop.org/systemd/systemd - ssh://git.freedesktop.org/git/systemd/systemd - -GITWEB: - http://cgit.freedesktop.org/systemd/systemd - -MAILING LIST: - http://lists.freedesktop.org/mailman/listinfo/systemd-devel - http://lists.freedesktop.org/mailman/listinfo/systemd-commits - -IRC: - #systemd on irc.freenode.org - -BUG REPORTS: - https://bugs.freedesktop.org/enter_bug.cgi?product=systemd - -AUTHOR: - Lennart Poettering - Kay Sievers - ...and many others - -LICENSE: - LGPLv2.1+ for all code - - except sd-daemon.[ch] and sd-readahead.[ch] which are MIT - - except src/udev/ which is GPLv2.0+, excluding - src/udev/libudev* which is LGPLv2.1+ - -REQUIREMENTS: - Linux kernel >= 2.6.39 - with devtmpfs - with cgroups (but it's OK to disable all controllers) - optional but strongly recommended: autofs4, ipv6 - libudev >= 172 - dbus >= 1.4.0 - libcap - PAM >= 1.1.2 (optional) - libcryptsetup (optional) - libaudit (optional) - libselinux (optional) - tcpwrappers (optional) - - When you build from git you need the following additional dependencies: - - docbook-xsl - xsltproc - automake - autoconf - libtool - gperf - make, gcc, and similar tools - - During runtime you need the following dependencies: - - util-linux > v2.18 (requires fsck -l, agetty -s) - sulogin (from sysvinit-tools, optional but recommended) - plymouth (optional) - dracut (optional) - - When systemd-hostnamed is used it is strongly recommended to - install nss-myhostname to ensure that in a world of - dynamically changing hostnames the hostname stays resolveable - under all circumstances. In fact, systemd-hostnamed will warn - if nss-myhostname is not installed. Packagers are encouraged to - add a dependency on nss-myhostname to the package that - includes systemd-hostnamed. - - Note that D-Bus can link against libsystemd-login.so, which - results in a cyclic build dependency. To accomodate for this - please build D-Bus without systemd first, then build systemd, - then rebuild D-Bus with systemd support. - -WARNINGS: - systemd will warn you during boot if /etc/mtab is not a - symlink to /proc/mounts. Please ensure that /etc/mtab is a - proper symlink. - - systemd will warn you during boot if /usr is on a different - file system than /. While in systemd itself very little will - break if /usr is on a separate partition many of its - dependencies very likely will break sooner or later in one - form or another. For example udev rules tend to refer to - binaries in /usr, binaries that link to libraries in /usr or - binaries that refer to data files in /usr. Since these - breakages are not always directly visible systemd will warn - about this, since this kind of file system setup is not really - supported anymore by the basic set of Linux OS components. - - For more information on this issue consult - http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken - -ENGINEERING AND CONSULTING SERVICES: - ProFUSION offers professional - engineering and consulting services for systemd for embedded - and other use. Please contact Gustavo Barbieri - for more information. - - Disclaimer: This notice is not a recommendation or official - endorsement. However, ProFUSION's upstream work has been very - beneficial for the systemd project. +Elogind User, Seat and Session Manager + +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/wingo/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/wingo/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, hybernate, +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. + +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)