README

   1 systemd System and Service Manager
   2
   3 DETAILS:
   4         http://0pointer.de/blog/projects/systemd.html
   5
   6 WEB SITE:
   7         http://www.freedesktop.org/wiki/Software/systemd
   8
   9 GIT:
  10         git://anongit.freedesktop.org/systemd/systemd
  11         ssh://git.freedesktop.org/git/systemd/systemd
  12
  13 GITWEB:
  14         http://cgit.freedesktop.org/systemd/systemd
  15
  16 MAILING LIST:
  17         http://lists.freedesktop.org/mailman/listinfo/systemd-devel
  18         http://lists.freedesktop.org/mailman/listinfo/systemd-commits
  19
  20 IRC:
  21         #systemd on irc.freenode.org
  22
  23 BUG REPORTS:
  24         https://bugs.freedesktop.org/enter_bug.cgi?product=systemd
  25
  26 AUTHOR:
  27         Lennart Poettering
  28         Kay Sievers
  29         ...and many others
  30
  31 LICENSE:
  32         LGPLv2.1+ for all code
  33         - except src/shared/MurmurHash2.c which is Public Domain
  34         - except src/shared/siphash24.c which is CC0 Public Domain
  35         - except src/journal/lookup3.c which is Public Domain
  36         - except src/udev/* which is (currently still) GPLv2, GPLv2+
  37
  38 REQUIREMENTS:
  39         Linux kernel >= 3.7
  40         Linux kernel >= 3.8 for Smack support
  41
  42         Kernel Config Options:
  43           CONFIG_DEVTMPFS
  44           CONFIG_CGROUPS (it is OK to disable all controllers)
  45           CONFIG_INOTIFY_USER
  46           CONFIG_SIGNALFD
  47           CONFIG_TIMERFD
  48           CONFIG_EPOLL
  49           CONFIG_NET
  50           CONFIG_SYSFS
  51           CONFIG_PROC_FS
  52           CONFIG_FHANDLE (libudev, mount and bind mount handling)
  53
  54         udev will fail to work with the legacy sysfs layout:
  55           CONFIG_SYSFS_DEPRECATED=n
  56
  57         Legacy hotplug slows down the system and confuses udev:
  58           CONFIG_UEVENT_HELPER_PATH=""
  59
  60         Userspace firmware loading is not supported and should
  61         be disabled in the kernel:
  62           CONFIG_FW_LOADER_USER_HELPER=n
  63
  64         Some udev rules and virtualization detection relies on it:
  65           CONFIG_DMIID
  66
  67         Support for some SCSI devices serial number retrieval, to
  68         create additional symlinks in /dev/disk/ and /dev/tape:
  69           CONFIG_BLK_DEV_BSG
  70
  71         Required for PrivateNetwork and PrivateDevices in service units:
  72           CONFIG_NET_NS
  73           CONFIG_DEVPTS_MULTIPLE_INSTANCES
  74         Note that systemd-localed.service and other systemd units use
  75         PrivateNetwork and PrivateDevices so this is effectively required.
  76
  77         Optional but strongly recommended:
  78           CONFIG_IPV6
  79           CONFIG_AUTOFS4_FS
  80           CONFIG_TMPFS_XATTR
  81           CONFIG_{TMPFS,EXT4,XFS,BTRFS_FS,...}_POSIX_ACL
  82           CONFIG_SECCOMP
  83           CONFIG_CHECKPOINT_RESTORE (for the kcmp() syscall)
  84
  85         Required for CPUShares in resource control unit settings
  86           CONFIG_CGROUP_SCHED
  87           CONFIG_FAIR_GROUP_SCHED
  88
  89         Required for CPUQuota in resource control unit settings
  90           CONFIG_CFS_BANDWIDTH
  91
  92         For systemd-bootchart, several proc debug interfaces are required:
  93           CONFIG_SCHEDSTATS
  94           CONFIG_SCHED_DEBUG
  95
  96         For UEFI systems:
  97           CONFIG_EFIVAR_FS
  98           CONFIG_EFI_PARTITION
  99
 100         Note that kernel auditing is broken when used with systemd's
 101         container code. When using systemd in conjunction with
 102         containers, please make sure to either turn off auditing at
 103         runtime using the kernel command line option "audit=0", or
 104         turn it off at kernel compile time using:
 105           CONFIG_AUDIT=n
 106         If systemd is compiled with libseccomp support on
 107         architectures which do not use socketcall() and where seccomp
 108         is supported (this effectively means x86-64 and ARM, but
 109         excludes 32-bit x86!), then nspawn will now install a
 110         work-around seccomp filter that makes containers boot even
 111         with audit being enabled. This works correctly only on kernels
 112         3.14 and newer though. TL;DR: turn audit off, still.
 113
 114         glibc >= 2.16
 115         libcap
 116         libmount >= 2.20 (from util-linux)
 117         libseccomp >= 1.0.0 (optional)
 118         libblkid >= 2.24 (from util-linux) (optional)
 119         libkmod >= 15 (optional)
 120         PAM >= 1.1.2 (optional)
 121         libcryptsetup (optional)
 122         libaudit (optional)
 123         libacl (optional)
 124         libselinux (optional)
 125         liblzma (optional)
 126         liblz4 >= 119 (optional)
 127         libgcrypt (optional)
 128         libqrencode (optional)
 129         libmicrohttpd (optional)
 130         libpython (optional)
 131         libidn (optional)
 132         gobject-introspection > 1.40.0 (optional)
 133         elfutils >= 158 (optional)
 134         make, gcc, and similar tools
 135
 136         During runtime, you need the following additional
 137         dependencies:
 138
 139         util-linux >= v2.26 required
 140         dbus >= 1.4.0 (strictly speaking optional, but recommended)
 141         dracut (optional)
 142         PolicyKit (optional)
 143
 144         When building from git, you need the following additional
 145         dependencies:
 146
 147         pkg-config
 148         docbook-xsl
 149         xsltproc
 150         automake
 151         autoconf
 152         libtool
 153         intltool
 154         gperf
 155         gtkdocize (optional)
 156         python (optional)
 157         python-lxml (optional, but required to build the indices)
 158         sphinx (optional)
 159
 160         When systemd-hostnamed is used, it is strongly recommended to
 161         install nss-myhostname to ensure that, in a world of
 162         dynamically changing hostnames, the hostname stays resolvable
 163         under all circumstances. In fact, systemd-hostnamed will warn
 164         if nss-myhostname is not installed.
 165
 166         To build HTML documentation for python-systemd using sphinx,
 167         please first install systemd (using 'make install'), and then
 168         invoke sphinx-build with 'make sphinx-<target>', with <target>
 169         being 'html' or 'latexpdf'. If using DESTDIR for installation,
 170         pass the same DESTDIR to 'make sphinx-html' invocation.
 171
 172 USERS AND GROUPS:
 173         Default udev rules use the following standard system group
 174         names, which need to be resolvable by getgrnam() at any time,
 175         even in the very early boot stages, where no other databases
 176         and network are available:
 177
 178         audio, cdrom, dialout, disk, input, kmem, lp, tape, tty, video
 179
 180         During runtime, the journal daemon requires the
 181         "systemd-journal" system group to exist. New journal files will
 182         be readable by this group (but not writable), which may be used
 183         to grant specific users read access. In addition, system
 184         groups "wheel" and "adm" will be given read-only access to
 185         journal files using systemd-tmpfiles.service.
 186
 187         The journal gateway daemon requires the
 188         "systemd-journal-gateway" system user and group to
 189         exist. During execution this network facing service will drop
 190         privileges and assume this uid/gid for security reasons.
 191
 192         Similarly, the NTP daemon requires the "systemd-timesync" system
 193         user and group to exist.
 194
 195         Similarly, the network management daemon requires the
 196         "systemd-network" system user and group to exist.
 197
 198         Similarly, the name resolution daemon requires the
 199         "systemd-resolve" system user and group to exist.
 200
 201         Similarly, the kdbus dbus1 proxy daemon requires the
 202         "systemd-bus-proxy" system user and group to exist.
 203
 204 NSS:
 205         systemd ships with three NSS modules:
 206
 207         nss-myhostname resolves the local hostname to locally
 208         configured IP addresses, as well as "localhost" to
 209         127.0.0.1/::1.
 210
 211         nss-resolve enables DNS resolution via the systemd-resolved
 212         DNS/LLMNR caching stub resolver "systemd-resolved".
 213
 214         nss-mymachines enables resolution of all local containers
 215         registered with machined to their respective IP addresses.
 216
 217         To make use of these NSS modules, please add them to the
 218         "hosts: " line in /etc/nsswitch.conf. The "resolve" module
 219         should replace the glibc "dns" module in this file.
 220
 221         The three modules should be used in the following order:
 222
 223                 hosts: files mymachines resolve myhostname
 224
 225 WARNINGS:
 226         systemd will warn you during boot if /etc/mtab is not a
 227         symlink to /proc/mounts. Please ensure that /etc/mtab is a
 228         proper symlink.
 229
 230         systemd will warn you during boot if /usr is on a different
 231         file system than /. While in systemd itself very little will
 232         break if /usr is on a separate partition, many of its
 233         dependencies very likely will break sooner or later in one
 234         form or another. For example, udev rules tend to refer to
 235         binaries in /usr, binaries that link to libraries in /usr or
 236         binaries that refer to data files in /usr. Since these
 237         breakages are not always directly visible, systemd will warn
 238         about this, since this kind of file system setup is not really
 239         supported anymore by the basic set of Linux OS components.
 240
 241         systemd requires that the /run mount point exists. systemd also
 242         requires that /var/run is a a symlink to /run.
 243
 244         For more information on this issue consult
 245         http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
 246
 247         To run systemd under valgrind, compile with VALGRIND defined
 248         (e.g. ./configure CPPFLAGS='... -DVALGRIND=1'). Otherwise,
 249         false positives will be triggered by code which violates
 250         some rules but is actually safe.
 251
 252 ENGINEERING AND CONSULTING SERVICES:
 253         ENDOCODE <https://endocode.com/> offers professional
 254         engineering and consulting services for systemd. Please
 255         contact Chris Kühl <chris@endocode.com> for more information.