Arch Knowledge Patch

Arch Linux Knowledge Patch

Reference index

Use this patch

1. Read the package-management reference before changing pacman.conf, maintaining PKGBUILDs, running private repositories, or automating pacman 7.0.0 or 7.1.0.
2. Check the intervention tables before a full system upgrade, especially on remote hosts, servers, and graphical workstations.
3. Read the relevant migration reference before accepting renamed packages, accounts, directories, units, or configuration formats.
4. Review .pacnew and .pacsave files instead of assuming package upgrades preserve local configuration.
5. Perform Arch upgrades as full upgrades; do not turn an intervention into a partial-upgrade workflow.

Breaking changes and required interventions

Restart OpenSSH after the 9.8p1 upgrade

Restart the daemon immediately after upgrading openssh to 9.8p1 because the old daemon cannot accept new connections:

systemctl try-restart sshd

On a remote host, preserve an existing session until the restarted daemon accepts a new connection.

Upgrade rsync everywhere

Upgrade every rsync daemon and client to Arch package 3.4.0-1 or newer, then reboot. Treat public mirrors as urgent: vulnerable anonymous servers can permit remote code execution, and hostile servers can attack connecting clients and sensitive files.

Remove retired pacman repositories

Remove [community], [community-testing], [testing], [testing-debug], [staging], and [staging-debug] from /etc/pacman.conf. Merge the .pacnew from pacman>=6.0.2-7; stale entries cause database synchronization to fail.

Resolve the split linux-firmware upgrade

For upgrades from linux-firmware 20250508.788aadc8-2 or earlier to 20250613.12fe085f-5 or newer, remove the old package without dependency checks and reinstall it during the full upgrade:

pacman -Rdd linux-firmware
pacman -Syu linux-firmware

Expect linux-firmware to become an empty dependency package backed by hardware-specific firmware packages.

Prepare Plasma X11 before Plasma 6.4

Install plasma-x11-session before upgrading an X11 workstation. Plasma 6.4 installs only the Wayland session by default after kwin splits into kwin-wayland and kwin-x11.

Rebuild 32-bit Wine prefixes

Recreate existing 32-bit prefixes and reinstall their applications after wine and wine-staging move to pure WoW64. Do not expect [multilib] to remain a dependency; anticipate slower direct OpenGL from some 32-bit applications.

Migrate Dovecot or pin the maintained 2.3 branch

Do not start Dovecot 2.4 with a 2.3-or-earlier configuration. Migrate it first, or install dovecot23 and the matching pigeonhole23 or dovecot23-fts-* packages when replication or delayed migration is required.

Handle transition-specific package conflicts

• Overwrite stale Waydroid .pyc files below /usr/lib/waydroid/tools/ when upgrading from before 1.5.4-3.
• Install the required -9.0 .NET package during the .NET 10 full upgrade, then remove its unversioned counterpart if version 9 must remain.
• Move Pascal, Maxwell, and older NVIDIA GPUs to AUR package nvidia-580xx-dkms before NVIDIA 590 replaces the closed modules with open kernel-module packages.
• Let Turing and newer GPUs transition automatically; do not apply the legacy-driver intervention to them.

Switch iptables backends deliberately

Treat iptables as the nft-backed package. Use iptables-legacy only for legacy-only behavior, inspect both rules .pacsave files when switching packages, restore rules as needed, and test uncommon xtables extensions.

Re-own Kea runtime state

After upgrading to kea>=1:3.0.3-6, assign existing state to the dedicated kea account and restart the services:

chown kea: /var/lib/kea/* /var/log/kea/* /run/lock/kea/logger_lockfile
systemctl try-restart kea-ctrl-agent.service kea-dhcp{4,6,-ddns}.service

Add interactive or service accounts to the kea group only when they require access to Kea leases, logs, or configuration.

Rename Varnish installations to Vinyl Cache

Migrate directories, accounts, commands, and systemd units from varnish names to vinyl names. Disable varnish.service and varnishncsa.service; enable vinyl-cache.service and vinylncsa.service after correcting state ownership.

Deprecations and platform migrations

Replace Redis with Valkey

Plan to move Arch-managed deployments from redis to Valkey. The Redis package was deprecated after its brief April 2025 transition in [extra], moved to the AUR, and stopped receiving Arch updates.

Move custom Zabbix files to the shared account

Change ownership and embedded account names in custom PSK files, scripts, sudoers rules, and configuration to the shared zabbix account introduced by zabbix-common. Complete this before deleting the old component-specific accounts.

Audit AUR changes before every update

During the ongoing malicious-package incident, inspect every change to each AUR package's PKGBUILD and install scripts before updating. Report suspicious commits for packages in use through the aur-general mailing list.

Pacman 7.0.0 and 7.1.0 defaults and sandboxing

Apply privilege-separated downloads

Merge pacman's .pacnew so Arch's DownloadUser default can take effect. Make each local repository traversable by the alpm group:

chown :alpm -R /path/to/local/repo
find /path/to/local/repo -type d -exec chmod g+x {} +

On Linux, expect the downloader to be unable to write outside its download directory. Prefer the fine-grained pacman 7.1.0 sandbox controls when one restriction is incompatible; use DisableSandbox or --disable-sandbox only when wholesale disablement is necessary.

Require signatures explicitly

Expect pacman 7.1.0's default SigLevel to be Required for packages and databases. Configure an intentional exception for unsigned local content; do not rely on the previous permissive default.

makepkg and PKGBUILD quick reference

Remove obsolete overrides

• Remove GITFLAGS; makepkg no longer supports it.
• Do not override BUILDENV or OPTIONS from a PKGBUILD.
• Do not use options=(!buildenv) to suppress MAKEFLAGS or CHOST.
• Expect Git operations to use /etc/makepkg.d/gitconfig while ignoring system Git configuration.

Use new packaging controls

• Set makepkg's own parallel-operation limit with NPROC; keep build-system parallelism separate.
• Store generic tracked data in xdata.
• Set per-architecture options with options_$arch.
• Use architecture-specific split packages where appropriate.
• Update Git-source checksums once when the stable, configuration-independent checksum logic changes an existing value, including for repositories using .gitattributes.

Serialize repository maintenance

Use repo-add --wait-for-lock when multiple writers may update a repository. Use repo-add --remove when the update should also delete old package files.

Detailed guidance

Load only the reference that matches the task:

• Read Package management for complete pacman, makepkg, repository, licensing, and firmware details.
• Read Service migrations for service-specific impact, package alternatives, account changes, directories, and unit names.
• Read Runtime and desktop transitions before upgrading affected graphical applications or language runtimes.
• Read Operations and security during Arch infrastructure outages or before any AUR update.