set nextpnr-xilinx seed 1 for deterministic behaviour

may be over-ridden with an argument override adding an additional
--seed {value}

diff --git a/nmigen/vendor/xilinx.py b/nmigen/vendor/xilinx.py
index 98b10bd36873fd08d11987acba559477f5732d21..c72d7289b71e317da53131c59b53cffe599c5c83 100644 (file)
--- a/nmigen/vendor/xilinx.py
+++ b/nmigen/vendor/xilinx.py
@@ -493,6 +493,7 @@ class XilinxPlatform(TemplatedPlatform):
             --json {{name}}.json
             --write {{name}}_routed.json
             --fasm {{name}}.fasm
+            --seed 1
         """,
         r"""
         {{invoke_tool("fasm2frames")}}