95 lines
3.2 KiB
Markdown
95 lines
3.2 KiB
Markdown
---
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title: Porting systemd To New Distributions
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category: Concepts
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layout: default
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---
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# Porting systemd To New Distributions
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## HOWTO
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You need to make the follow changes to adapt systemd to your
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distribution:
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1. Find the right configure parameters for:
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* `-Drootprefix=`
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* `-Dsysvinit-path=`
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* `-Dsysvrcnd-path=`
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* `-Drc-local=`
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* `-Dloadkeys-path=`
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* `-Dsetfont-path=`
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* `-Dtty-gid=`
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* `-Dntp-servers=`
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* `-Ddns-servers=`
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* `-Dsupport-url=`
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2. Try it out.
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Play around (as an ordinary user) with
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`/usr/lib/systemd/systemd --test --system` for a test run
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of systemd without booting. This will read the unit files and
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print the initial transaction it would execute during boot-up.
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This will also inform you about ordering loops and suchlike.
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## Compilation options
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The default configuration does not enable any optimization or hardening
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options. This is suitable for development and testing, but not for end-user
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installations.
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For deployment, optimization (`-O2` or `-O3` compiler options), link time
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optimization (`-Db_lto=true` meson option), and hardening (e.g.
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`-D_FORTIFY_SOURCE=2`, `-fstack-protector-strong`, `-fstack-clash-protection`,
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`-fcf-protection`, `-pie` compiler options, and `-z relro`, `-z now`,
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`--as-needed` linker options) are recommended. The most appropriate set of
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options depends on the architecture and distribution specifics so no default is
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provided.
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## NTP Pool
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By default, systemd-timesyncd uses the Google Public NTP servers
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`time[1-4].google.com`, if no other NTP configuration is available.
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They serve time that uses a
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[leap second smear](https://developers.google.com/time/smear)
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and can be up to .5s off from servers that use stepped leap seconds.
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If you prefer to use leap second steps, please register your own
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vendor pool at ntp.org and make it the built-in default by
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passing `-Dntp-servers=` to meson. Registering vendor
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pools is [free](http://www.pool.ntp.org/en/vendors.html).
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Use `-Dntp-servers=` to direct systemd-timesyncd to different fallback
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NTP servers.
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## DNS Servers
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By default, systemd-resolved uses Cloudflare and Google Public DNS servers
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`1.1.1.1`, `8.8.8.8`, `1.0.0.1`, `8.8.4.4`, `2606:4700:4700::1111`, `2001:4860:4860::8888`, `2606:4700:4700::1001`, `2001:4860:4860::8844`
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as fallback, if no other DNS configuration is available.
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Use `-Ddns-servers=` to direct systemd-resolved to different fallback
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DNS servers.
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## PAM
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The default PAM config shipped by systemd is really bare bones.
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It does not include many modules your distro might want to enable
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to provide a more seamless experience. For example, limits set in
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`/etc/security/limits.conf` will not be read unless you load `pam_limits`.
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Make sure you add modules your distro expects from user services.
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Pass `-Dpamconfdir=no` to meson to avoid installing this file and
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instead install your own.
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## Contributing Upstream
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We generally do no longer accept distribution-specific patches to
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systemd upstream. If you have to make changes to systemd's source code
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to make it work on your distribution, unless your code is generic
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enough to be generally useful, we are unlikely to merge it. Please
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always consider adopting the upstream defaults. If that is not
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possible, please maintain the relevant patches downstream.
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Thank you for understanding.
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