diff --git a/tests/vm/README.md b/tests/vm/README.md
index 5e5a91c..628c2dc 100644
--- a/tests/vm/README.md
+++ b/tests/vm/README.md
@@ -76,3 +76,17 @@ start.sh server.
 
 Memory: server 4 GiB + one client 2 GiB (start.sh refuses a second client). Keep other VMs (win11) off while
 both run, and stop them when done.
+
+Blancco needs more client RAM than 2 GiB: blancco-init downloads its
+~850 MB rootfs into a tmpfs, and at 2 GiB it stops at 48% with "No space
+left on device". To test it within the 6 GiB budget, shrink the server and
+grow the client while both are off, and put them back afterwards:
+
+    virsh -c qemu:///system setmaxmem pxetest-server 2048M --config
+    virsh -c qemu:///system setmem    pxetest-server 2048M --config
+    virsh -c qemu:///system setmaxmem pxetest-client 4096M --config
+    virsh -c qemu:///system setmem    pxetest-client 4096M --config
+
+Menu keys from the host: `virsh -c qemu:///system send-key <vm> KEY_DOWN`
+(separator lines are skipped: Down x1 = Blancco, x3 = Clonezilla,
+x4 = Memtest), then KEY_ENTER; startnet answers are KEY_<digit> + KEY_ENTER.