diff --git a/Makefile b/Makefile
index dadd556..9504c30 100644
--- a/Makefile
+++ b/Makefile
@@ -804,6 +804,7 @@ projects:
 # CFLAGS and make cannot see that.
 # -----------------------------------------------------------------------
 iso:
+	@$(MAKE) --no-print-directory ldls-r8169-if-present
 	$(MAKE) RAMROOT=1 schos.iso
 
 # One El Torito entry, pointing at a FAT image holding the loader and kernel.
@@ -1427,6 +1428,15 @@ ldls-r8169:
 	    *)     cp $$f $(SYSROOT)/lib/firmware/rtl_nic/;; esac; done
 	@echo "staged Linux r8169 ($(shell uname -r)) into $(SYSROOT)"
 
+# `make iso` runs this first: the ISO ships Linux's r8169 set (NOTICE), so stage it whenever
+# this machine has the modules and the BTF to stage it from, and say so when it does not.
+ldls-r8169-if-present:
+	@if ls $(LDLS_KDIR)/drivers/net/ethernet/realtek/r8169.ko* >/dev/null 2>&1 && [ -r /sys/kernel/btf/vmlinux ]; then \
+	    $(MAKE) --no-print-directory ldls-r8169; \
+	else \
+	    echo "iso: no Linux r8169 modules or BTF on this machine ($(LDLS_KDIR)) -- this ISO will not carry them"; \
+	fi
+
 ldls-unstage:
 	rm -rf $(SYSROOT)/lib/modules
 	@echo "removed"
@@ -1497,6 +1507,10 @@ etc-install: $(SCHINIT_JOBS) $(ETC_PLAIN) $(ETC_ZSH) $(LOGO_ASCII) $(SRV_FILES)
 	@mkdir -p $(SYSROOT)/usr/share/hwdata
 	@rm -f $(SYSROOT)/usr/share/usb.ids
 	@for f in usb.ids pci.ids; do [ -f dist/$$f ] && cp -p dist/$$f $(SYSROOT)/usr/share/hwdata/; done; true
+	@# The licences travel with the image: SchOS's, xv6's, and NOTICE, which carries the
+	@# third-party ones -- including Linux's r8169 modules, whose source offer it records.
+	@mkdir -p $(SYSROOT)/usr/share/licenses/schos
+	@cp -p LICENSE LICENSE.MIT NOTICE $(SYSROOT)/usr/share/licenses/schos/
 	@echo "installed $(words $(ETC_PLAIN)) /etc file(s), $(words $(ETC_ZSH)) zsh file(s) and $(words $(SCHINIT_JOBS)) schinit manifest(s)"
 
 # The mount points. Created here rather than by init, because a mkdir on a
@@ -1844,4 +1858,4 @@ distclean: clean
 -include $(shell find $(BUILD) \( -path $(BUILD)/aroot -o -path $(BUILD)/iso -o -path $(BUILD)/ports \) -prune -o -type f -name '*.d' -print 2>/dev/null)
 
 FORCE:
-.PHONY: FORCE
+.PHONY: FORCE ldls-r8169-if-present
diff --git a/docs/architecture/desktop.md b/docs/architecture/desktop.md
index df56968..8be437c 100644
--- a/docs/architecture/desktop.md
+++ b/docs/architecture/desktop.md
@@ -40,11 +40,12 @@ the real program is for.
 ## The four files
 
 - **`/root/.xserverrc`** starts `X` on the VT `startx` was started from (startx works that
-  out only when `uname -s` says Linux, and SchOS's says SchIFT) with **`-dumbSched`**. Xorg
-  normally reads input on a thread of its own; when SchOS had no threads the server crashed
-  the first time a client disconnected, in `pthread_join` on a thread that was never made, and
-  `-dumbSched` is Xorg's own switch for input on the main loop. Threads exist now; the switch
-  is still on, and nobody has run the server without it since.
+  out only when `uname -s` says Linux, and SchOS's says SchIFT). It used to add **`-dumbSched`**,
+  Xorg's switch for reading input on the main loop, because Xorg normally reads input on a
+  thread of its own and, when SchOS had no threads, the server crashed the first time a client
+  disconnected, in `pthread_join` on a thread that was never made. Threads exist now and the switch
+  is gone: under QEMU, X starts with Window Maker, `xclock` and `xeyes` connect and disconnect, an
+  `xterm` runs and exits, and the server stays up.
 - **`/root/.xinitrc`** is `exec wmaker`. Without it xinit falls back to twm and an xterm, which
   are not in the image.
 - **`/etc/X11/xorg.conf.d/10-schos.conf`** names the input devices. Alpine's Xorg asks udev for
diff --git a/tools/posix/mkaroot.sh b/tools/posix/mkaroot.sh
index c0eb688..dcfb269 100644
--- a/tools/posix/mkaroot.sh
+++ b/tools/posix/mkaroot.sh
@@ -97,12 +97,12 @@ mkdir -p "$P/etc/profile.d"
 grep -v '^export \(PATH\|HOME\|TERM\)=' "$P/etc/profile" > "$P/etc/profile.d/schos.sh"
 rm -f "$P/etc/profile"
 
-# How startx starts the X server for root: Alpine's xserverrc, plus
-# -dumbSched. Xorg reads input on a thread of its own; when SchOS had no threads
-# the server crashed on its way out the first time a client disconnected, in
-# pthread_join on a thread that was never made. -dumbSched is Xorg's own switch
-# for input on the main loop. SchOS has threads now (clone, futex), so this may
-# no longer be needed -- it has simply not been tried without it. The file is
+# How startx starts the X server for root: Alpine's xserverrc. (It used to add
+# -dumbSched, Xorg's switch for reading input on the main loop, because when SchOS
+# had no threads the server crashed on its way out the first time a client
+# disconnected, in pthread_join on a thread that was never made. SchOS has threads
+# now; X was run without the switch under QEMU -- clients connecting and
+# disconnecting, an xterm starting and exiting -- and it stays up.) The file is
 # root's own rather than /etc/X11/xinit/xserverrc, which belongs to the xinit
 # package.
 mkdir -p "$P/root"
@@ -111,7 +111,7 @@ cat > "$P/root/.xserverrc" <<'XEOF'
 # The VT X runs on is the one startx was started from. startx works that out
 # only when `uname -s` says Linux, and SchOS's says SchIFT.
 vt=$(tty | sed -n 's|^/dev/tty\([0-9][0-9]*\)$|vt\1|p')
-exec /usr/bin/X -nolisten tcp -dumbSched $vt "$@"
+exec /usr/bin/X -nolisten tcp $vt "$@"
 XEOF
 
 # What startx runs inside it: Window Maker, which world installs. Without this