DF-5282 fix-build log (guest, fix.diff applied to /usr/src copy; never applied to the read-only audit tree)

$ cd /usr/src && patch --dry-run < /tmp/fix.diff
Patching file sys/bus/u4b/controller/ehci.c using Plan A...
Hunk #1 succeeded at 327.
$ patch < /tmp/fix.diff
Patching file sys/bus/u4b/controller/ehci.c using Plan A...
Hunk #1 succeeded at 327.
done
$ grep -n "invalid register geometry" sys/bus/u4b/controller/ehci.c
346:		device_printf(sc->sc_bus.bdev, "invalid register geometry: "

$ make quickkernel KERNCONF=X86_64_GENERIC   (tail)
>>> Kernel build for X86_64_GENERIC completed on Fri Oct  2 00:58:41 UTC 2026 <<<
$ make installkernel KERNCONF=X86_64_GENERIC (tail)
>>> Kernel install for X86_64_GENERIC completed on Fri Oct  2 00:59:43 UTC 2026 <<<
KERNEL-INSTALLED

post-reboot verification:
  - /boot/kernel/ehci.ko mtime 00:58 (fresh); strings | grep -c "invalid register geometry" => 1
  - kldstat => "2    1 0xffffffff81d01000    760b8 ehci.ko"  (patched module loaded)
  - no-regression: ehci0 attaches, usbus0 480Mbps, ugen0.1 root hub + ugen0.2 keyboard enumerated