X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=README;h=27cc9a01681829af75365e8c06272be4ffbe7dc9;hp=9891c696d374c95765dabc307dbb37db57bc106c;hb=d228dab58edda06f13e9637cffb16f48a6a615cb;hpb=da4aec2fb4e3c9f1f73a67a5e326c90220fb0c59 diff --git a/README b/README index 9891c696d..27cc9a016 100644 --- a/README +++ b/README @@ -1,107 +1,276 @@ +systemd System and Service Manager -udev - a userspace device manager - -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 at /sys. No other location is supported. - You can mount it by running: - mount -t sysfs none /sys - -- Make sure you integrate udev with your hotplug setup. There is a copy of - the rules files for all major distros in the etc/udev folder. You may look - there how others are doing it. - -- Make sure you integrate with the kernel hotplug events. Later versions of - udev are able to listen directly to a netlink socket, older versions used - udevsend to feed the udev daemon with the kernel event. The most basic - setup to run udev is to let the kernel for the udev binary directly: - echo "/sbin/udev" > /proc/sys/kernel/hotplug - - While this may work in some setups, it is not recommended to do. A recent - kernel and udev version is able to operate with the event serializing daemon - udevd, that makes sure, that no "remove" event will beat a "add" event for - the same device. - -- 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. - EXTRAS - if set, will build the "extra" helper programs as specified - as listed (see below for an example.) - - So, if you want to build udev using klibc with debugging messages, you - would do: - make USE_KLIBC=true DEBUG=true - - If you want to build the udev helper program cdrom_id and scsi_id you - would do: - make EXTRAS="extras/cdrom_id extras/scsi_id" - - udev will follow the setting of the debug level in udev.conf. Adapt this - value to see the debug in syslog. - -- Install the project: - make install - - This will put the udev binaries in /sbin, create the 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 /dev based on the device types. - -- If you later get sick of it, uninstall it: - make uninstall - -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. Running udevstart should populate an empty /dev -directory. You may test, if a node is recreated after running udevstart. - -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 +DETAILS: + http://0pointer.de/blog/projects/systemd.html +WEB SITE: + http://www.freedesktop.org/wiki/Software/systemd + +GIT: + git@github.com:systemd/systemd.git + https://github.com/systemd/systemd.git + +GITWEB: + https://github.com/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://github.com/systemd/systemd/issues + +AUTHOR: + Lennart Poettering + Kay Sievers + ...and many others + +LICENSE: + LGPLv2.1+ for all code + - except src/basic/MurmurHash2.c which is Public Domain + - except src/basic/siphash24.c which is CC0 Public Domain + - except src/journal/lookup3.c which is Public Domain + - except src/udev/* which is (currently still) GPLv2, GPLv2+ + +REQUIREMENTS: + Linux kernel >= 3.11 + Linux kernel >= 4.2 for unified cgroup hierarchy support + + Kernel Config Options: + CONFIG_DEVTMPFS + CONFIG_CGROUPS (it is OK to disable all controllers) + CONFIG_INOTIFY_USER + CONFIG_SIGNALFD + CONFIG_TIMERFD + CONFIG_EPOLL + CONFIG_NET + CONFIG_SYSFS + CONFIG_PROC_FS + CONFIG_FHANDLE (libudev, mount and bind mount handling) + + udev will fail to work with the legacy sysfs layout: + CONFIG_SYSFS_DEPRECATED=n + + Legacy hotplug slows down the system and confuses udev: + CONFIG_UEVENT_HELPER_PATH="" + + Userspace firmware loading is not supported and should + be disabled in the kernel: + CONFIG_FW_LOADER_USER_HELPER=n + + Some udev rules and virtualization detection relies on it: + CONFIG_DMIID + + Support for some SCSI devices serial number retrieval, to + create additional symlinks in /dev/disk/ and /dev/tape: + CONFIG_BLK_DEV_BSG + + Required for PrivateNetwork and PrivateDevices in service units: + CONFIG_NET_NS + CONFIG_DEVPTS_MULTIPLE_INSTANCES + Note that systemd-localed.service and other systemd units use + PrivateNetwork and PrivateDevices so this is effectively required. + + Optional but strongly recommended: + CONFIG_IPV6 + CONFIG_AUTOFS4_FS + CONFIG_TMPFS_XATTR + CONFIG_{TMPFS,EXT4,XFS,BTRFS_FS,...}_POSIX_ACL + CONFIG_SECCOMP + CONFIG_CHECKPOINT_RESTORE (for the kcmp() syscall) + + Required for CPUShares= in resource control unit settings + CONFIG_CGROUP_SCHED + CONFIG_FAIR_GROUP_SCHED + + Required for CPUQuota= in resource control unit settings + CONFIG_CFS_BANDWIDTH + + For systemd-bootchart, several proc debug interfaces are required: + CONFIG_SCHEDSTATS + CONFIG_SCHED_DEBUG + + For UEFI systems: + CONFIG_EFIVAR_FS + CONFIG_EFI_PARTITION + + We recommend to turn off Real-Time group scheduling in the + kernel when using systemd. RT group scheduling effectively + makes RT scheduling unavailable for most userspace, since it + requires explicit assignment of RT budgets to each unit whose + processes making use of RT. As there's no sensible way to + assign these budgets automatically this cannot really be + fixed, and it's best to disable group scheduling hence. + CONFIG_RT_GROUP_SCHED=n + + Note that kernel auditing is broken when used with systemd's + container code. When using systemd in conjunction with + containers, please make sure to either turn off auditing at + runtime using the kernel command line option "audit=0", or + turn it off at kernel compile time using: + CONFIG_AUDIT=n + If systemd is compiled with libseccomp support on + architectures which do not use socketcall() and where seccomp + is supported (this effectively means x86-64 and ARM, but + excludes 32-bit x86!), then nspawn will now install a + work-around seccomp filter that makes containers boot even + with audit being enabled. This works correctly only on kernels + 3.14 and newer though. TL;DR: turn audit off, still. + + glibc >= 2.16 + libcap + libmount >= 2.20 (from util-linux) + libseccomp >= 1.0.0 (optional) + libblkid >= 2.24 (from util-linux) (optional) + libkmod >= 15 (optional) + PAM >= 1.1.2 (optional) + libcryptsetup (optional) + libaudit (optional) + libacl (optional) + libselinux (optional) + liblzma (optional) + liblz4 >= 119 (optional) + libgcrypt (optional) + libqrencode (optional) + libmicrohttpd (optional) + libpython (optional) + libidn (optional) + elfutils >= 158 (optional) + make, gcc, and similar tools + + During runtime, you need the following additional + dependencies: + + util-linux >= v2.26 required + dbus >= 1.4.0 (strictly speaking optional, but recommended) + dracut (optional) + PolicyKit (optional) + + When building from git, the following tools are needed: + + pkg-config + docbook-xsl + xsltproc + automake + autoconf + libtool + intltool + gperf + python (optional) + python-lxml (optional, but required to build the indices) + sphinx (optional) + + The build system is initialized with ./autogen.sh. A tar ball + can be created with: + git archive --format=tar --prefix=systemd-222/ v222 | xz > systemd-222.tar.xz + + 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 resolvable + under all circumstances. In fact, systemd-hostnamed will warn + if nss-myhostname is not installed. + + To build HTML documentation for python-systemd using sphinx, + please first install systemd (using 'make install'), and then + invoke sphinx-build with 'make sphinx-', with + being 'html' or 'latexpdf'. If using DESTDIR for installation, + pass the same DESTDIR to 'make sphinx-html' invocation. + +USERS AND GROUPS: + Default udev rules use the following standard system group + names, which need to be resolvable by getgrnam() at any time, + even in the very early boot stages, where no other databases + and network are available: + + audio, cdrom, dialout, disk, input, kmem, lp, tape, tty, video + + During runtime, the journal daemon requires the + "systemd-journal" system group to exist. New journal files will + be readable by this group (but not writable), which may be used + to grant specific users read access. In addition, system + groups "wheel" and "adm" will be given read-only access to + journal files using systemd-tmpfiles.service. + + The journal gateway daemon requires the + "systemd-journal-gateway" system user and group to + exist. During execution this network facing service will drop + privileges and assume this uid/gid for security reasons. + + Similarly, the NTP daemon requires the "systemd-timesync" system + user and group to exist. + + Similarly, the network management daemon requires the + "systemd-network" system user and group to exist. + + Similarly, the name resolution daemon requires the + "systemd-resolve" system user and group to exist. + + Similarly, the kdbus dbus1 proxy daemon requires the + "systemd-bus-proxy" system user and group to exist. + +NSS: + systemd ships with three NSS modules: + + nss-myhostname resolves the local hostname to locally + configured IP addresses, as well as "localhost" to + 127.0.0.1/::1. + + nss-resolve enables DNS resolution via the systemd-resolved + DNS/LLMNR caching stub resolver "systemd-resolved". + + nss-mymachines enables resolution of all local containers + registered with machined to their respective IP addresses. + + To make use of these NSS modules, please add them to the + "hosts: " line in /etc/nsswitch.conf. The "resolve" module + should replace the glibc "dns" module in this file. + + The three modules should be used in the following order: + + hosts: files mymachines resolve myhostname + +SYSV INIT.D SCRIPTS: + When calling "systemctl enable/disable/is-enabled" on a unit which is a + SysV init.d script, it calls /usr/lib/systemd/systemd-sysv-install; + this needs to translate the action into the distribution specific + mechanism such as chkconfig or update-rc.d. Packagers need to provide + this script if you need this functionality (you don't if you disabled + SysV init support). + + Please see src/systemctl/systemd-sysv-install.SKELETON for how this + needs to look like, and provide an implementation at the marked places. + +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. + + systemd requires that the /run mount point exists. systemd also + requires that /var/run is a symlink to /run. + + For more information on this issue consult + http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken + + To run systemd under valgrind, compile with VALGRIND defined + (e.g. ./configure CPPFLAGS='... -DVALGRIND=1'). Otherwise, + false positives will be triggered by code which violates + some rules but is actually safe. + + Currently, systemd-timesyncd defaults to use the Google NTP + servers if not specified otherwise at configure time. You + really should not ship an OS or device with this default + setting. See DISTRO_PORTING for details.