Simmer barley, covered in water, for 30 minutes; cool to lukewarm (about 130°F). Add olive oil.
Combine flours, yeast, salt, sugar and rosemary in food processor with metal blade. Add barley mixture and process until mixture forms a ball. (Add small amount of liquid or flour to ensure soft dough, if needed). Remove and knead in walnuts.
Form into round loaf; place on greased baking sheet. Cover and let rise until doubled (30-45 minutes). Bake at 375°F, 35 to 45 minutes, until hollow sounding when thumped. Slice thinly.
