DF-3170/DF-3171 fix validation kernel build (guest /usr/src, in-guest logs lost to
post-install reboot of tmpfs /tmp — this file assembles the decisive lines
captured in the build/install ssh sessions, 2026-09-07 16:04-16:19 UTC).

Applied in-guest to /usr/src:
  patch -p1 < /tmp/fix3170.diff          (DF-3170 spinlock fix; applied clean, 5 hunks)
  patch -p1 < /tmp/fix3171b.diff         (DF-3171 si_mountpoint guard; applied clean)

Build:
  cd /usr/src && make -j6 nativekernel
  ...
  CCVER=gcc80 CC=cc mkdep -f .depend -a ... /usr/src/sys/vfs/mfs/mfs_vfsops.c
  --- mfs_vfsops.o ---
  cc -c -O2 -pipe -Wall ... -Werror /usr/src/sys/vfs/mfs/mfs_vfsops.c     [kernel]
  cc -O2 -pipe -D_KERNEL -Wall ... -Werror -DKLD_MODULE ... mfs_vfsops.c  [module]
  (both compiled clean with -Werror; no warnings, no errors)
  ...
  >>> Kernel build for X86_64_GENERIC completed on Mon Sep  7 16:14:13 UTC 2026
  --------------------------------------------------------------
  cd /usr/src && make installkernel
  >>> Kernel install for X86_64_GENERIC completed on Mon Sep  7 16:19:46 UTC 2026
  /boot/kernel/kernel -> 119352624 bytes Sep  7 16:18

Patched kernel booted after reboot:
  DragonFly dfbsd 6.5-DEVELOPMENT #1: Mon Sep  7 16:11:15 UTC 2026
  root@dfbsd:/usr/obj/usr/src/sys/X86_64_GENERIC  x86_64
  (stock baseline was #0: Thu Jul 2 06:02:54 UTC 2026)