component = {}
function component.list(filter)
        io.stdout:write("listing:"..filter.."\n")
        local ret = {}
        function test(name)
                -- todo, substring search
                if filter == name then
                        return true
                elseif filter == nil then
                        return true
                end
                return false
        end
        if test("eeprom") then ret["56af8068-b597-4336-bfdb-b9df970309d8"] = "eeprom" end
        if test("screen") then ret["73822386-3f58-4d0b-8fad-fdf5a34d0a8a"] = "screen" end
        if test("gpu") then ret["1d721b0c-b681-4b80-ba46-7eacbc6d1cfb"] = "gpu" end
        for k,v in pairs(ret) do print(k,v) end
        return function () return ret end
end