Survive kernel updates on a /boot this small

A dnf upgrade to 7.1.8 installed the kernel rpm cleanly, then ran /boot out
of space. dracut wrote no initramfs, and because kernel-install stops at the
first failing plugin, 95-c630-devicetree never ran either — leaving a boot
entry with neither an initrd nor a devicetree line, which on this machine can
never boot. dnf reported success and nothing retried.

A kernel costs ~336 MiB here: a 210 MiB hostonly=no initramfs, a 98 MiB
dtb-<kver> directory carrying every board's device tree, plus vmlinuz and
System.map. Three of those cannot fit 1 GiB, so /boot goes to 2 GiB and
installonly_limit drops to 2.

Also fixes the quieter half of the same trap. snd-soc-wsa881x lives outside
the kernel package, so the speakers go silent after any kernel update with
nothing in the logs to explain it. c630-wsa881x rebuilds it and
96-c630-wsa881x.install calls it on each kernel-install add — always exiting
0, since a plugin failure is precisely what caused the damage above.

grub.cfg gains the next_entry one-shot block that has been carried by hand all
along, so testing a kernel costs a power cycle rather than a rescue.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011XgGF5wfxLDAybVnNz6eNQ

overlay/etc/dnf/libdnf5.conf.d/50-c630-installonly.conf

@@ -0,0 +1,23 @@
+# Keep two kernels, not the stock three.
+#
+# This machine's initramfs is unusually large — hostonly is off (see
+# /etc/dracut.conf.d/10-c630.conf) so every image carries the full driver and
+# firmware set, and each installed kernel costs roughly:
+#
+#     initramfs  ~210 MiB
+#     dtb-<kver>  ~98 MiB   (kernel-core ships every board's device tree)
+#     vmlinuz     ~17 MiB
+#     System.map  ~11 MiB
+#     ---------------------
+#     total      ~336 MiB
+#
+# Three of those is ~1008 MiB, which does not fit a 1 GiB /boot. The failure is
+# nastier than a full disk: dnf installs the kernel rpm successfully, then
+# dracut dies on ENOSPC, and because kernel-install stops at the first failing
+# plugin, 95-c630-devicetree never runs either. The result is a boot entry with
+# no initrd and no devicetree — unbootable — while dnf reports success and
+# never retries.
+#
+# Two kernels is ~672 MiB, which leaves comfortable headroom.
+[main]
+installonly_limit=2

overlay/etc/kernel/install.d/96-c630-wsa881x.install

@@ -0,0 +1,37 @@
+#!/usr/bin/bash
+#
+# Rebuild the speaker-amplifier module for each new kernel.
+#
+# snd-soc-wsa881x is not in any Fedora package (see c630-wsa881x), so it lives
+# in /lib/modules/<kver>/extra and has to be rebuilt whenever a kernel is
+# installed. Without this the speakers go silent the first time you run
+# `dnf upgrade`, and nothing in the logs connects the two events.
+#
+# This runs at 96, after 95-c630-devicetree, because it must not come between
+# 90-loaderentry.install — which rewrites the BLS entry — and the hook that
+# puts the devicetree line back.
+#
+# It always exits 0. kernel-install stops at the first plugin that fails, and
+# this machine has already been bitten once by that: a full /boot made
+# 50-dracut.install fail, which meant 95-c630-devicetree never ran, which left
+# a boot entry with neither an initrd nor a devicetree. Silent speakers are
+# worth a warning; they are not worth an unbootable machine.
+
+set -u
+
+COMMAND="${1:?}"
+KERNEL_VERSION="${2:?}"
+
+[ "$COMMAND" = "add" ] || exit 0
+
+if ! command -v c630-wsa881x >/dev/null; then
+    exit 0
+fi
+
+if ! c630-wsa881x "$KERNEL_VERSION"; then
+    echo "96-c630-wsa881x: could not build snd-soc-wsa881x for ${KERNEL_VERSION};" \
+         "the built-in speakers will be silent on that kernel until you run" \
+         "'sudo c630-wsa881x ${KERNEL_VERSION}'" >&2
+fi
+
+exit 0