diff --git a/src/entity_manager/overlay.cpp b/src/entity_manager/overlay.cpp
new file mode 100644
index 0000000..8b52fb9
--- /dev/null
+++ b/src/entity_manager/overlay.cpp
@@ -0,0 +1,323 @@
+/*
+// Copyright (c) 2018 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+*/
+/// \file overlay.cpp
+
+#include "overlay.hpp"
+
+#include "../utils.hpp"
+#include "devices.hpp"
+
+#include <boost/algorithm/string/predicate.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/steady_timer.hpp>
+#include <boost/container/flat_map.hpp>
+#include <boost/container/flat_set.hpp>
+#include <boost/process/child.hpp>
+#include <nlohmann/json.hpp>
+#include <phosphor-logging/lg2.hpp>
+
+#include <filesystem>
+#include <iomanip>
+#include <iostream>
+#include <regex>
+#include <string>
+
+constexpr const char* outputDir = "/tmp/overlays";
+constexpr const char* templateChar = "$";
+constexpr const char* i2CDevsDir = "/sys/bus/i2c/devices";
+constexpr const char* muxSymlinkDir = "/dev/i2c-mux";
+
+const std::regex illegalNameRegex("[^A-Za-z0-9_]");
+
+// helper function to make json types into string
+std::string jsonToString(const nlohmann::json& in)
+{
+    if (in.type() == nlohmann::json::value_t::string)
+    {
+        return in.get<std::string>();
+    }
+    if (in.type() == nlohmann::json::value_t::array)
+    {
+        // remove brackets and comma from array
+        std::string array = in.dump();
+        array = array.substr(1, array.size() - 2);
+        boost::replace_all(array, ",", " ");
+        return array;
+    }
+    return in.dump();
+}
+
+static std::string deviceDirName(uint64_t bus, uint64_t address)
+{
+    std::ostringstream name;
+    name << bus << "-" << std::hex << std::setw(4) << std::setfill('0')
+         << address;
+    return name.str();
+}
+
+void linkMux(const std::string& muxName, uint64_t busIndex, uint64_t address,
+             const std::vector<std::string>& channelNames)
+{
+    std::error_code ec;
+    std::filesystem::path muxSymlinkDirPath(muxSymlinkDir);
+    std::filesystem::create_directory(muxSymlinkDirPath, ec);
+    // ignore error codes here if the directory already exists
+    ec.clear();
+    std::filesystem::path linkDir = muxSymlinkDirPath / muxName;
+    std::filesystem::create_directory(linkDir, ec);
+
+    std::filesystem::path devDir(i2CDevsDir);
+    devDir /= deviceDirName(busIndex, address);
+
+    for (std::size_t channelIndex = 0; channelIndex < channelNames.size();
+         channelIndex++)
+    {
+        const std::string& channelName = channelNames[channelIndex];
+        if (channelName.empty())
+        {
+            continue;
+        }
+
+        std::filesystem::path channelPath =
+            devDir / ("channel-" + std::to_string(channelIndex));
+        if (!is_symlink(channelPath))
+        {
+            std::cerr << channelPath << " for mux channel " << channelName
+                      << " doesn't exist!\n";
+            continue;
+        }
+        std::filesystem::path bus = std::filesystem::read_symlink(channelPath);
+
+        std::filesystem::path fp("/dev" / bus.filename());
+        std::filesystem::path link(linkDir / channelName);
+
+        std::filesystem::create_symlink(fp, link, ec);
+        if (ec)
+        {
+            std::cerr << "Failure creating symlink for " << fp << " to " << link
+                      << "\n";
+        }
+    }
+}
+
+static int deleteDevice(const std::string& busPath, uint64_t address,
+                        const std::string& destructor)
+{
+    std::filesystem::path deviceDestructor(busPath);
+    deviceDestructor /= destructor;
+    std::ofstream deviceFile(deviceDestructor);
+    if (!deviceFile.good())
+    {
+        std::cerr << "Error writing " << deviceDestructor << "\n";
+        return -1;
+    }
+    deviceFile << std::to_string(address);
+    deviceFile.close();
+    return 0;
+}
+
+static int createDevice(const std::string& busPath,
+                        const std::string& parameters,
+                        const std::string& constructor)
+{
+    std::filesystem::path deviceConstructor(busPath);
+    deviceConstructor /= constructor;
+    std::ofstream deviceFile(deviceConstructor);
+    if (!deviceFile.good())
+    {
+        std::cerr << "Error writing " << deviceConstructor << "\n";
+        return -1;
+    }
+    deviceFile << parameters;
+    deviceFile.close();
+
+    return 0;
+}
+
+static bool deviceIsCreated(const std::string& busPath, uint64_t bus,
+                            uint64_t address,
+                            const devices::createsHWMon hasHWMonDir)
+{
+    std::filesystem::path dirPath = busPath;
+    dirPath /= deviceDirName(bus, address);
+    if (hasHWMonDir == devices::createsHWMon::hasHWMonDir)
+    {
+        dirPath /= "hwmon";
+    }
+
+    std::error_code ec;
+    // Ignore errors; anything but a clean 'true' is just fine as 'false'
+    return std::filesystem::exists(dirPath, ec);
+}
+
+static int buildDevice(
+    const std::string& name, const std::string& busPath,
+    const std::string& parameters, uint64_t bus, uint64_t address,
+    const std::string& constructor, const std::string& destructor,
+    const devices::createsHWMon hasHWMonDir,
+    std::vector<std::string> channelNames, const size_t retries = 5)
+{
+    if (retries == 0U)
+    {
+        return -1;
+    }
+
+    // If it's already instantiated, we don't need to create it again.
+    if (!deviceIsCreated(busPath, bus, address, hasHWMonDir))
+    {
+        // Try to create the device
+        createDevice(busPath, parameters, constructor);
+
+        // If it didn't work, delete it and try again in 500ms
+        if (!deviceIsCreated(busPath, bus, address, hasHWMonDir))
+        {
+            deleteDevice(busPath, address, destructor);
+
+            std::shared_ptr<boost::asio::steady_timer> createTimer =
+                std::make_shared<boost::asio::steady_timer>(io);
+            createTimer->expires_after(std::chrono::milliseconds(500));
+            createTimer->async_wait(
+                [createTimer, name, busPath, parameters, bus, address,
+                 constructor, destructor, hasHWMonDir,
+                 channelNames(std::move(channelNames)),
+                 retries](const boost::system::error_code& ec) mutable {
+                    if (ec)
+                    {
+                        std::cerr << "Timer error: " << ec << "\n";
+                        return -2;
+                    }
+                    return buildDevice(name, busPath, parameters, bus, address,
+                                       constructor, destructor, hasHWMonDir,
+                                       std::move(channelNames), retries - 1);
+                });
+            return -1;
+        }
+    }
+
+    // Link the mux channels if needed once the device is created.
+    if (!channelNames.empty())
+    {
+        linkMux(name, bus, address, channelNames);
+    }
+
+    return 0;
+}
+
+void exportDevice(const std::string& type,
+                  const devices::ExportTemplate& exportTemplate,
+                  const nlohmann::json& configuration)
+{
+    std::string parameters = exportTemplate.parameters;
+    std::string busPath = exportTemplate.busPath;
+    std::string constructor = exportTemplate.add;
+    std::string destructor = exportTemplate.remove;
+    devices::createsHWMon hasHWMonDir = exportTemplate.hasHWMonDir;
+    std::string name = "unknown";
+    std::optional<uint64_t> bus;
+    std::optional<uint64_t> address;
+    std::vector<std::string> channels;
+
+    for (auto keyPair = configuration.begin(); keyPair != configuration.end();
+         keyPair++)
+    {
+        std::string subsituteString;
+
+        if (keyPair.key() == "Name" &&
+            keyPair.value().type() == nlohmann::json::value_t::string)
+        {
+            subsituteString = std::regex_replace(
+                keyPair.value().get<std::string>(), illegalNameRegex, "_");
+            name = subsituteString;
+        }
+        else
+        {
+            subsituteString = jsonToString(keyPair.value());
+        }
+
+        if (keyPair.key() == "Bus")
+        {
+            bus = keyPair.value().get<uint64_t>();
+        }
+        else if (keyPair.key() == "Address")
+        {
+            address = keyPair.value().get<uint64_t>();
+        }
+        else if (keyPair.key() == "ChannelNames" && type.ends_with("Mux"))
+        {
+            channels = keyPair.value().get<std::vector<std::string>>();
+        }
+        boost::replace_all(parameters, templateChar + keyPair.key(),
+                           subsituteString);
+        boost::replace_all(busPath, templateChar + keyPair.key(),
+                           subsituteString);
+    }
+
+    if (!bus || !address)
+    {
+        createDevice(busPath, parameters, constructor);
+        return;
+    }
+
+    buildDevice(name, busPath, parameters, *bus, *address, constructor,
+                destructor, hasHWMonDir, std::move(channels));
+}
+
+bool loadOverlays(const nlohmann::json& systemConfiguration)
+{
+    std::filesystem::create_directory(outputDir);
+    for (auto entity = systemConfiguration.begin();
+         entity != systemConfiguration.end(); entity++)
+    {
+        auto findExposes = entity.value().find("Exposes");
+        if (findExposes == entity.value().end() ||
+            findExposes->type() != nlohmann::json::value_t::array)
+        {
+            continue;
+        }
+
+        for (const auto& configuration : *findExposes)
+        {
+            auto findStatus = configuration.find("Status");
+            // status missing is assumed to be 'okay'
+            if (findStatus != configuration.end() && *findStatus == "disabled")
+            {
+                continue;
+            }
+            auto findType = configuration.find("Type");
+            if (findType == configuration.end() ||
+                findType->type() != nlohmann::json::value_t::string)
+            {
+                continue;
+            }
+            std::string type = findType.value().get<std::string>();
+            auto device = devices::exportTemplates.find(type.c_str());
+            if (device != devices::exportTemplates.end())
+            {
+                exportDevice(type, device->second, configuration);
+                continue;
+            }
+
+            // Because many devices are intentionally not exportable,
+            // this error message is not printed in all situations.
+            // If wondering why your device not appearing, add your type to
+            // the exportTemplates array in the devices.hpp file.
+            lg2::debug("Device type {TYPE} not found in export map allowlist",
+                       "TYPE", type);
+        }
+    }
+
+    return true;
+}