mirror of
https://github.com/systemd/systemd.git
synced 2024-11-27 12:13:33 +08:00
888e378da2
Let's add an extra-safety net and change UID/GID to the "systemd-coredump" user when processing coredumps from system user. For coredumps of normal users we keep the current logic of processing the coredumps from the user id the coredump was created under. Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=87354
273 lines
10 KiB
Plaintext
273 lines
10 KiB
Plaintext
systemd System and Service Manager
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DETAILS:
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http://0pointer.de/blog/projects/systemd.html
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WEB SITE:
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http://www.freedesktop.org/wiki/Software/systemd
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GIT:
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git@github.com:systemd/systemd.git
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https://github.com/systemd/systemd.git
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GITWEB:
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https://github.com/systemd/systemd
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MAILING LIST:
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http://lists.freedesktop.org/mailman/listinfo/systemd-devel
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IRC:
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#systemd on irc.freenode.org
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BUG REPORTS:
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https://github.com/systemd/systemd/issues
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AUTHOR:
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Lennart Poettering
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Kay Sievers
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...and many others
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LICENSE:
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LGPLv2.1+ for all code
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- except src/basic/MurmurHash2.c which is Public Domain
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- except src/basic/siphash24.c which is CC0 Public Domain
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- except src/journal/lookup3.c which is Public Domain
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- except src/udev/* which is (currently still) GPLv2, GPLv2+
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REQUIREMENTS:
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Linux kernel >= 3.11
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Linux kernel >= 4.2 for unified cgroup hierarchy support
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Kernel Config Options:
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CONFIG_DEVTMPFS
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CONFIG_CGROUPS (it is OK to disable all controllers)
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CONFIG_INOTIFY_USER
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CONFIG_SIGNALFD
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CONFIG_TIMERFD
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CONFIG_EPOLL
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CONFIG_NET
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CONFIG_SYSFS
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CONFIG_PROC_FS
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CONFIG_FHANDLE (libudev, mount and bind mount handling)
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udev will fail to work with the legacy sysfs layout:
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CONFIG_SYSFS_DEPRECATED=n
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Legacy hotplug slows down the system and confuses udev:
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CONFIG_UEVENT_HELPER_PATH=""
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Userspace firmware loading is not supported and should
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be disabled in the kernel:
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CONFIG_FW_LOADER_USER_HELPER=n
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Some udev rules and virtualization detection relies on it:
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CONFIG_DMIID
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Support for some SCSI devices serial number retrieval, to
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create additional symlinks in /dev/disk/ and /dev/tape:
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CONFIG_BLK_DEV_BSG
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Required for PrivateNetwork and PrivateDevices in service units:
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CONFIG_NET_NS
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CONFIG_DEVPTS_MULTIPLE_INSTANCES
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Note that systemd-localed.service and other systemd units use
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PrivateNetwork and PrivateDevices so this is effectively required.
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Optional but strongly recommended:
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CONFIG_IPV6
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CONFIG_AUTOFS4_FS
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CONFIG_TMPFS_XATTR
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CONFIG_{TMPFS,EXT4,XFS,BTRFS_FS,...}_POSIX_ACL
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CONFIG_SECCOMP
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CONFIG_CHECKPOINT_RESTORE (for the kcmp() syscall)
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Required for CPUShares= in resource control unit settings
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CONFIG_CGROUP_SCHED
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CONFIG_FAIR_GROUP_SCHED
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Required for CPUQuota= in resource control unit settings
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CONFIG_CFS_BANDWIDTH
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For systemd-bootchart, several proc debug interfaces are required:
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CONFIG_SCHEDSTATS
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CONFIG_SCHED_DEBUG
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For UEFI systems:
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CONFIG_EFIVAR_FS
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CONFIG_EFI_PARTITION
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We recommend to turn off Real-Time group scheduling in the
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kernel when using systemd. RT group scheduling effectively
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makes RT scheduling unavailable for most userspace, since it
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requires explicit assignment of RT budgets to each unit whose
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processes making use of RT. As there's no sensible way to
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assign these budgets automatically this cannot really be
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fixed, and it's best to disable group scheduling hence.
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CONFIG_RT_GROUP_SCHED=n
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Note that kernel auditing is broken when used with systemd's
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container code. When using systemd in conjunction with
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containers, please make sure to either turn off auditing at
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runtime using the kernel command line option "audit=0", or
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turn it off at kernel compile time using:
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CONFIG_AUDIT=n
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If systemd is compiled with libseccomp support on
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architectures which do not use socketcall() and where seccomp
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is supported (this effectively means x86-64 and ARM, but
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excludes 32-bit x86!), then nspawn will now install a
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work-around seccomp filter that makes containers boot even
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with audit being enabled. This works correctly only on kernels
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3.14 and newer though. TL;DR: turn audit off, still.
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glibc >= 2.16
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libcap
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libmount >= 2.27.1 (from util-linux)
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libseccomp >= 1.0.0 (optional)
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libblkid >= 2.24 (from util-linux) (optional)
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libkmod >= 15 (optional)
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PAM >= 1.1.2 (optional)
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libcryptsetup (optional)
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libaudit (optional)
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libacl (optional)
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libselinux (optional)
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liblzma (optional)
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liblz4 >= 119 (optional)
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libgcrypt (optional)
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libqrencode (optional)
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libmicrohttpd (optional)
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libpython (optional)
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libidn (optional)
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elfutils >= 158 (optional)
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make, gcc, and similar tools
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During runtime, you need the following additional
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dependencies:
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util-linux >= v2.27.1 required
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dbus >= 1.4.0 (strictly speaking optional, but recommended)
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dracut (optional)
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PolicyKit (optional)
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When building from git, the following tools are needed:
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pkg-config
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docbook-xsl
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xsltproc
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automake
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autoconf
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libtool
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intltool
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gperf
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python (optional)
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python-lxml (optional, but required to build the indices)
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The build system is initialized with ./autogen.sh. A tar ball
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can be created with:
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git archive --format=tar --prefix=systemd-222/ v222 | xz > systemd-222.tar.xz
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When systemd-hostnamed is used, it is strongly recommended to
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install nss-myhostname to ensure that, in a world of
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dynamically changing hostnames, the hostname stays resolvable
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under all circumstances. In fact, systemd-hostnamed will warn
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if nss-myhostname is not installed.
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USERS AND GROUPS:
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Default udev rules use the following standard system group
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names, which need to be resolvable by getgrnam() at any time,
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even in the very early boot stages, where no other databases
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and network are available:
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audio, cdrom, dialout, disk, input, kmem, lp, tape, tty, video
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During runtime, the journal daemon requires the
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"systemd-journal" system group to exist. New journal files will
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be readable by this group (but not writable), which may be used
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to grant specific users read access. In addition, system
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groups "wheel" and "adm" will be given read-only access to
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journal files using systemd-tmpfiles.service.
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The journal gateway daemon requires the
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"systemd-journal-gateway" system user and group to
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exist. During execution this network facing service will drop
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privileges and assume this uid/gid for security reasons.
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Similarly, the NTP daemon requires the "systemd-timesync" system
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user and group to exist.
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Similarly, the network management daemon requires the
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"systemd-network" system user and group to exist.
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Similarly, the name resolution daemon requires the
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"systemd-resolve" system user and group to exist.
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Similarly, the kdbus dbus1 proxy daemon requires the
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"systemd-bus-proxy" system user and group to exist.
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Similarly, the coredump support requires the
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"systemd-coredump" system user and group to exist.
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NSS:
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systemd ships with three NSS modules:
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nss-myhostname resolves the local hostname to locally
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configured IP addresses, as well as "localhost" to
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127.0.0.1/::1.
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nss-resolve enables DNS resolution via the systemd-resolved
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DNS/LLMNR caching stub resolver "systemd-resolved".
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nss-mymachines enables resolution of all local containers
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registered with machined to their respective IP addresses.
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To make use of these NSS modules, please add them to the
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"hosts: " line in /etc/nsswitch.conf. The "resolve" module
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should replace the glibc "dns" module in this file.
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The three modules should be used in the following order:
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hosts: files mymachines resolve myhostname
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SYSV INIT.D SCRIPTS:
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When calling "systemctl enable/disable/is-enabled" on a unit which is a
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SysV init.d script, it calls /usr/lib/systemd/systemd-sysv-install;
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this needs to translate the action into the distribution specific
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mechanism such as chkconfig or update-rc.d. Packagers need to provide
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this script if you need this functionality (you don't if you disabled
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SysV init support).
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Please see src/systemctl/systemd-sysv-install.SKELETON for how this
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needs to look like, and provide an implementation at the marked places.
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WARNINGS:
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systemd will warn you during boot if /usr is on a different
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file system than /. While in systemd itself very little will
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break if /usr is on a separate partition, many of its
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dependencies very likely will break sooner or later in one
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form or another. For example, udev rules tend to refer to
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binaries in /usr, binaries that link to libraries in /usr or
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binaries that refer to data files in /usr. Since these
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breakages are not always directly visible, systemd will warn
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about this, since this kind of file system setup is not really
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supported anymore by the basic set of Linux OS components.
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systemd requires that the /run mount point exists. systemd also
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requires that /var/run is a symlink to /run.
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For more information on this issue consult
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http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
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To run systemd under valgrind, compile with VALGRIND defined
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(e.g. ./configure CPPFLAGS='... -DVALGRIND=1'). Otherwise,
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false positives will be triggered by code which violates
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some rules but is actually safe.
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Currently, systemd-timesyncd defaults to use the Google NTP
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servers if not specified otherwise at configure time. You
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really should not ship an OS or device with this default
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setting. See DISTRO_PORTING for details.
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ENGINEERING AND CONSULTING SERVICES:
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Kinvolk (https://kinvolk.io) offers professional engineering
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and consulting services for systemd. Please contact Chris Kühl
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<chris@kinvolk.io> for more information.
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