@@ -294,6 +294,18 @@ function max_vcpus {

     # Assert ithas a numeric nonzero value

     expr "$cpu_count" + 0

+    # 8 VCPUs should be enough for devstack VM; avoid using too

+    # many VCPUs:

+    # 1. too many VCPUs may trigger a kernel bug which result VM

+    #    not able to boot:

+    #    https://kernel.googlesource.com/pub/scm/linux/kernel/git/wsa/linux/+/e2e004acc7cbe3c531e752a270a74e95cde3ea48

+    # 2. The remaining CPUs can be used for other purpose:

+    #    e.g. boot test VMs.

+    MAX_VCPUS=8

+    if [ $cpu_count -ge $MAX_VCPUS ]; then

+        cpu_count=$MAX_VCPUS

+    fi

+

     xe vm-param-set uuid=$vm VCPUs-max=$cpu_count

     xe vm-param-set uuid=$vm VCPUs-at-startup=$cpu_count

 }