From 0b1322d1c68903390c45ed6496dd896e1f93cf3e Mon Sep 17 00:00:00 2001
From: enricobuehler <buehler@unom.io>
Date: Fri, 12 Jun 2026 22:41:45 +0000
Subject: [PATCH] fix(packaging): ship the UDP socket-buffer sysctl in the .deb
 and .rpm
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The host requests a 32 MB SO_SNDBUF, but the kernel clamps it to net.core.wmem_max
(~416 KB on a stock box) — so high-bitrate frames overflow the socket buffer and
the host drops a large fraction of packets on send (measured 28.5% loss / 54k
dropped at 1 Gbps to a clean LAN client on a fresh Bazzite box). scripts/99-punktfunk-net.conf
fixes it (32 MB caps) but the packages never installed it. Ship it to
/usr/lib/sysctl.d/ (auto-applied at boot by systemd-sysctl) and apply it in the
deb/rpm postinst. This is the dominant cause of the sub-Gbps ceiling on an
untuned host.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 packaging/debian/build-deb.sh | 5 +++++
 packaging/rpm/punktfunk.spec  | 8 ++++++++
 2 files changed, 13 insertions(+)

diff --git a/packaging/debian/build-deb.sh b/packaging/debian/build-deb.sh
index 6414105..3c5a5de 100755
--- a/packaging/debian/build-deb.sh
+++ b/packaging/debian/build-deb.sh
@@ -37,6 +37,9 @@ SHAREDIR="$STAGE/usr/share/$PKG"
 # --- file layout (matches the RPM %install) ----------------------------------
 install -Dm0755 "$BIN"                              "$STAGE/usr/bin/$PKG"
 install -Dm0644 scripts/60-punktfunk.rules         "$STAGE/usr/lib/udev/rules.d/60-punktfunk.rules"
+# UDP socket-buffer tuning (32 MB) — without it the kernel clamps the host's SO_SNDBUF to ~416 KB
+# and high-bitrate frames overflow it (send-side packet loss). systemd-sysctl applies it at boot.
+install -Dm0644 scripts/99-punktfunk-net.conf      "$STAGE/usr/lib/sysctl.d/99-punktfunk-net.conf"
 install -Dm0644 scripts/punktfunk-host.service     "$STAGE/usr/lib/systemd/user/punktfunk-host.service"
 install -Dm0755 scripts/headless/run-headless-kde.sh   "$SHAREDIR/headless/run-headless-kde.sh"
 install -Dm0755 scripts/headless/run-headless-sway.sh  "$SHAREDIR/headless/run-headless-sway.sh"
@@ -133,6 +136,8 @@ if [ "$1" = "configure" ]; then
     # Pick up the /dev/uinput rule without a reboot (best-effort, no-op in containers).
     udevadm control --reload-rules 2>/dev/null || true
     udevadm trigger --subsystem-match=misc 2>/dev/null || true
+    # Apply the UDP socket-buffer tuning now (also auto-applied at boot by systemd-sysctl).
+    sysctl -p /usr/lib/sysctl.d/99-punktfunk-net.conf >/dev/null 2>&1 || true
     echo "punktfunk-host installed. Add yourself to the 'input' group for virtual gamepads:"
     echo "    sudo usermod -aG input \"\$USER\"   # then re-login"
     echo "Config:  mkdir -p ~/.config/punktfunk && cp /usr/share/punktfunk-host/host.env.example ~/.config/punktfunk/host.env"
diff --git a/packaging/rpm/punktfunk.spec b/packaging/rpm/punktfunk.spec
index aaf57fa..8ab60da 100644
--- a/packaging/rpm/punktfunk.spec
+++ b/packaging/rpm/punktfunk.spec
@@ -112,6 +112,10 @@ install -Dm0755 target/release/punktfunk-host %{buildroot}%{_bindir}/punktfunk-h
 # udev rule — /dev/uinput access for virtual gamepads (input group).
 install -Dm0644 scripts/60-punktfunk.rules %{buildroot}%{_udevrulesdir}/60-punktfunk.rules
 
+# UDP socket-buffer tuning (32 MB) — without it the kernel clamps the host's SO_SNDBUF to ~416 KB
+# and high-bitrate frames overflow it (send-side loss). systemd-sysctl applies it at boot.
+install -Dm0644 scripts/99-punktfunk-net.conf %{buildroot}%{_prefix}/lib/sysctl.d/99-punktfunk-net.conf
+
 # systemd *user* unit (the host runs in the graphical session, not as root).
 install -Dm0644 scripts/punktfunk-host.service %{buildroot}%{_userunitdir}/punktfunk-host.service
 
@@ -128,6 +132,7 @@ install -Dm0644 docs/api/openapi.json                  %{buildroot}%{_datadir}/%
 %doc README.md docs/implementation-plan.md packaging/README.md
 %{_bindir}/punktfunk-host
 %{_udevrulesdir}/60-punktfunk.rules
+%{_prefix}/lib/sysctl.d/99-punktfunk-net.conf
 %{_userunitdir}/punktfunk-host.service
 %dir %{_datadir}/%{name}
 %{_datadir}/%{name}/*
@@ -136,6 +141,9 @@ install -Dm0644 docs/api/openapi.json                  %{buildroot}%{_datadir}/%
 # Reload udev so /dev/uinput picks up the new rule without a reboot (best-effort).
 udevadm control --reload-rules 2>/dev/null || :
 udevadm trigger --subsystem-match=misc 2>/dev/null || :
+# Apply the UDP socket-buffer tuning (also auto-applied at boot by systemd-sysctl; on rpm-ostree
+# it takes effect on the next boot into the layered deployment).
+sysctl -p %{_prefix}/lib/sysctl.d/99-punktfunk-net.conf >/dev/null 2>&1 || :
 echo "punktfunk installed. Add yourself to the 'input' group (sudo usermod -aG input \$USER)"
 echo "then enable the host: systemctl --user enable --now punktfunk-host"
 echo "Config: cp %{_datadir}/%{name}/host.env.bazzite ~/.config/punktfunk/host.env"