37 files changed, 1303 insertions, 50 deletions

diff --git a/src/common/common_paths.h b/src/common/common_paths.h
index df2ce80b1..4f88de768 100644
--- a/src/common/common_paths.h
+++ b/src/common/common_paths.h
@@ -33,6 +33,8 @@
 #define NAND_DIR "nand"
 #define SYSDATA_DIR "sysdata"
 #define KEYS_DIR "keys"
+#define LOAD_DIR "load"
+#define DUMP_DIR "dump"
 #define LOG_DIR "log"
 
 // Filenames
diff --git a/src/common/file_util.cpp b/src/common/file_util.cpp
index 21a0b9738..548463787 100644
--- a/src/common/file_util.cpp
+++ b/src/common/file_util.cpp
@@ -705,6 +705,8 @@ const std::string& GetUserPath(UserPath path, const std::string& new_path) {
 #endif
         paths.emplace(UserPath::SDMCDir, user_path + SDMC_DIR DIR_SEP);
         paths.emplace(UserPath::NANDDir, user_path + NAND_DIR DIR_SEP);
+        paths.emplace(UserPath::LoadDir, user_path + LOAD_DIR DIR_SEP);
+        paths.emplace(UserPath::DumpDir, user_path + DUMP_DIR DIR_SEP);
         paths.emplace(UserPath::SysDataDir, user_path + SYSDATA_DIR DIR_SEP);
         paths.emplace(UserPath::KeysDir, user_path + KEYS_DIR DIR_SEP);
         // TODO: Put the logs in a better location for each OS
diff --git a/src/common/file_util.h b/src/common/file_util.h
index 24c1e413c..3d8fe6264 100644
--- a/src/common/file_util.h
+++ b/src/common/file_util.h
@@ -29,6 +29,8 @@ enum class UserPath {
     NANDDir,
     RootDir,
     SDMCDir,
+    LoadDir,
+    DumpDir,
     SysDataDir,
     UserDir,
 };
diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index 26f727d96..23fd6e920 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -32,6 +32,8 @@ add_library(core STATIC
     file_sys/control_metadata.h
     file_sys/directory.h
     file_sys/errors.h
+    file_sys/fsmitm_romfsbuild.cpp
+    file_sys/fsmitm_romfsbuild.h
     file_sys/mode.h
     file_sys/nca_metadata.cpp
     file_sys/nca_metadata.h
@@ -59,10 +61,13 @@ add_library(core STATIC
     file_sys/vfs.h
     file_sys/vfs_concat.cpp
     file_sys/vfs_concat.h
+    file_sys/vfs_layered.cpp
+    file_sys/vfs_layered.h
     file_sys/vfs_offset.cpp
     file_sys/vfs_offset.h
     file_sys/vfs_real.cpp
     file_sys/vfs_real.h
+    file_sys/vfs_static.h
     file_sys/vfs_vector.cpp
     file_sys/vfs_vector.h
     file_sys/xts_archive.cpp
diff --git a/src/core/core.cpp b/src/core/core.cpp
index 50f0a42fb..7666354dc 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -64,7 +64,7 @@ FileSys::VirtualFile GetGameFileFromPath(const FileSys::VirtualFilesystem& vfs,
         if (concat.empty())
             return nullptr;
 
-        return FileSys::ConcatenateFiles(concat, dir->GetName());
+        return FileSys::ConcatenatedVfsFile::MakeConcatenatedFile(concat, dir->GetName());
     }
 
     return vfs->OpenFile(path, FileSys::Mode::Read);
diff --git a/src/core/file_sys/bis_factory.cpp b/src/core/file_sys/bis_factory.cpp
index 205492897..6102ef476 100644
--- a/src/core/file_sys/bis_factory.cpp
+++ b/src/core/file_sys/bis_factory.cpp
@@ -2,13 +2,14 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <fmt/format.h>
 #include "core/file_sys/bis_factory.h"
 #include "core/file_sys/registered_cache.h"
 
 namespace FileSys {
 
-BISFactory::BISFactory(VirtualDir nand_root_)
-    : nand_root(std::move(nand_root_)),
+BISFactory::BISFactory(VirtualDir nand_root_, VirtualDir load_root_)
+    : nand_root(std::move(nand_root_)), load_root(std::move(load_root_)),
       sysnand_cache(std::make_shared<RegisteredCache>(
           GetOrCreateDirectoryRelative(nand_root, "/system/Contents/registered"))),
       usrnand_cache(std::make_shared<RegisteredCache>(
@@ -24,4 +25,11 @@ std::shared_ptr<RegisteredCache> BISFactory::GetUserNANDContents() const {
     return usrnand_cache;
 }
 
+VirtualDir BISFactory::GetModificationLoadRoot(u64 title_id) const {
+    // LayeredFS doesn't work on updates and title id-less homebrew
+    if (title_id == 0 || (title_id & 0x800) > 0)
+        return nullptr;
+    return GetOrCreateDirectoryRelative(load_root, fmt::format("/{:016X}", title_id));
+}
+
 } // namespace FileSys
diff --git a/src/core/file_sys/bis_factory.h b/src/core/file_sys/bis_factory.h
index 9523dd864..c352e0925 100644
--- a/src/core/file_sys/bis_factory.h
+++ b/src/core/file_sys/bis_factory.h
@@ -17,14 +17,17 @@ class RegisteredCache;
 /// registered caches.
 class BISFactory {
 public:
-    explicit BISFactory(VirtualDir nand_root);
+    explicit BISFactory(VirtualDir nand_root, VirtualDir load_root);
     ~BISFactory();
 
     std::shared_ptr<RegisteredCache> GetSystemNANDContents() const;
     std::shared_ptr<RegisteredCache> GetUserNANDContents() const;
 
+    VirtualDir GetModificationLoadRoot(u64 title_id) const;
+
 private:
     VirtualDir nand_root;
+    VirtualDir load_root;
 
     std::shared_ptr<RegisteredCache> sysnand_cache;
     std::shared_ptr<RegisteredCache> usrnand_cache;
diff --git a/src/core/file_sys/fsmitm_romfsbuild.cpp b/src/core/file_sys/fsmitm_romfsbuild.cpp
new file mode 100644
index 000000000..07b074817
--- /dev/null
+++ b/src/core/file_sys/fsmitm_romfsbuild.cpp
@@ -0,0 +1,367 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * Adapted by DarkLordZach for use/interaction with yuzu
+ *
+ * Modifications Copyright 2018 yuzu emulator team
+ * Licensed under GPLv2 or any later version
+ * Refer to the license.txt file included.
+ */
+
+#include <cstring>
+#include "common/assert.h"
+#include "core/file_sys/fsmitm_romfsbuild.h"
+#include "core/file_sys/vfs.h"
+#include "core/file_sys/vfs_vector.h"
+
+namespace FileSys {
+
+constexpr u64 FS_MAX_PATH = 0x301;
+
+constexpr u32 ROMFS_ENTRY_EMPTY = 0xFFFFFFFF;
+constexpr u32 ROMFS_FILEPARTITION_OFS = 0x200;
+
+// Types for building a RomFS.
+struct RomFSHeader {
+    u64 header_size;
+    u64 dir_hash_table_ofs;
+    u64 dir_hash_table_size;
+    u64 dir_table_ofs;
+    u64 dir_table_size;
+    u64 file_hash_table_ofs;
+    u64 file_hash_table_size;
+    u64 file_table_ofs;
+    u64 file_table_size;
+    u64 file_partition_ofs;
+};
+static_assert(sizeof(RomFSHeader) == 0x50, "RomFSHeader has incorrect size.");
+
+struct RomFSDirectoryEntry {
+    u32 parent;
+    u32 sibling;
+    u32 child;
+    u32 file;
+    u32 hash;
+    u32 name_size;
+};
+static_assert(sizeof(RomFSDirectoryEntry) == 0x18, "RomFSDirectoryEntry has incorrect size.");
+
+struct RomFSFileEntry {
+    u32 parent;
+    u32 sibling;
+    u64 offset;
+    u64 size;
+    u32 hash;
+    u32 name_size;
+};
+static_assert(sizeof(RomFSFileEntry) == 0x20, "RomFSFileEntry has incorrect size.");
+
+struct RomFSBuildFileContext;
+
+struct RomFSBuildDirectoryContext {
+    std::string path;
+    u32 cur_path_ofs = 0;
+    u32 path_len = 0;
+    u32 entry_offset = 0;
+    std::shared_ptr<RomFSBuildDirectoryContext> parent;
+    std::shared_ptr<RomFSBuildDirectoryContext> child;
+    std::shared_ptr<RomFSBuildDirectoryContext> sibling;
+    std::shared_ptr<RomFSBuildFileContext> file;
+};
+
+struct RomFSBuildFileContext {
+    std::string path;
+    u32 cur_path_ofs = 0;
+    u32 path_len = 0;
+    u32 entry_offset = 0;
+    u64 offset = 0;
+    u64 size = 0;
+    std::shared_ptr<RomFSBuildDirectoryContext> parent;
+    std::shared_ptr<RomFSBuildFileContext> sibling;
+    VirtualFile source;
+};
+
+static u32 romfs_calc_path_hash(u32 parent, std::string path, u32 start, std::size_t path_len) {
+    u32 hash = parent ^ 123456789;
+    for (u32 i = 0; i < path_len; i++) {
+        hash = (hash >> 5) | (hash << 27);
+        hash ^= path[start + i];
+    }
+
+    return hash;
+}
+
+static u64 romfs_get_hash_table_count(u64 num_entries) {
+    if (num_entries < 3) {
+        return 3;
+    }
+
+    if (num_entries < 19) {
+        return num_entries | 1;
+    }
+
+    u64 count = num_entries;
+    while (count % 2 == 0 || count % 3 == 0 || count % 5 == 0 || count % 7 == 0 ||
+           count % 11 == 0 || count % 13 == 0 || count % 17 == 0) {
+        count++;
+    }
+    return count;
+}
+
+void RomFSBuildContext::VisitDirectory(VirtualDir root_romfs,
+                                       std::shared_ptr<RomFSBuildDirectoryContext> parent) {
+    std::vector<std::shared_ptr<RomFSBuildDirectoryContext>> child_dirs;
+
+    VirtualDir dir;
+
+    if (parent->path_len == 0)
+        dir = root_romfs;
+    else
+        dir = root_romfs->GetDirectoryRelative(parent->path);
+
+    const auto entries = dir->GetEntries();
+
+    for (const auto& kv : entries) {
+        if (kv.second == VfsEntryType::Directory) {
+            const auto child = std::make_shared<RomFSBuildDirectoryContext>();
+            // Set child's path.
+            child->cur_path_ofs = parent->path_len + 1;
+            child->path_len = child->cur_path_ofs + static_cast<u32>(kv.first.size());
+            child->path = parent->path + "/" + kv.first;
+
+            // Sanity check on path_len
+            ASSERT(child->path_len < FS_MAX_PATH);
+
+            if (AddDirectory(parent, child)) {
+                child_dirs.push_back(child);
+            }
+        } else {
+            const auto child = std::make_shared<RomFSBuildFileContext>();
+            // Set child's path.
+            child->cur_path_ofs = parent->path_len + 1;
+            child->path_len = child->cur_path_ofs + static_cast<u32>(kv.first.size());
+            child->path = parent->path + "/" + kv.first;
+
+            // Sanity check on path_len
+            ASSERT(child->path_len < FS_MAX_PATH);
+
+            child->source = root_romfs->GetFileRelative(child->path);
+
+            child->size = child->source->GetSize();
+
+            AddFile(parent, child);
+        }
+    }
+
+    for (auto& child : child_dirs) {
+        this->VisitDirectory(root_romfs, child);
+    }
+}
+
+bool RomFSBuildContext::AddDirectory(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                                     std::shared_ptr<RomFSBuildDirectoryContext> dir_ctx) {
+    // Check whether it's already in the known directories.
+    const auto existing = directories.find(dir_ctx->path);
+    if (existing != directories.end())
+        return false;
+
+    // Add a new directory.
+    num_dirs++;
+    dir_table_size +=
+        sizeof(RomFSDirectoryEntry) + ((dir_ctx->path_len - dir_ctx->cur_path_ofs + 3) & ~3);
+    dir_ctx->parent = parent_dir_ctx;
+    directories.emplace(dir_ctx->path, dir_ctx);
+
+    return true;
+}
+
+bool RomFSBuildContext::AddFile(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                                std::shared_ptr<RomFSBuildFileContext> file_ctx) {
+    // Check whether it's already in the known files.
+    const auto existing = files.find(file_ctx->path);
+    if (existing != files.end()) {
+        return false;
+    }
+
+    // Add a new file.
+    num_files++;
+    file_table_size +=
+        sizeof(RomFSFileEntry) + ((file_ctx->path_len - file_ctx->cur_path_ofs + 3) & ~3);
+    file_ctx->parent = parent_dir_ctx;
+    files.emplace(file_ctx->path, file_ctx);
+
+    return true;
+}
+
+RomFSBuildContext::RomFSBuildContext(VirtualDir base_) : base(std::move(base_)) {
+    root = std::make_shared<RomFSBuildDirectoryContext>();
+    root->path = "\0";
+    directories.emplace(root->path, root);
+    num_dirs = 1;
+    dir_table_size = 0x18;
+
+    VisitDirectory(base, root);
+}
+
+RomFSBuildContext::~RomFSBuildContext() = default;
+
+std::map<u64, VirtualFile> RomFSBuildContext::Build() {
+    const u64 dir_hash_table_entry_count = romfs_get_hash_table_count(num_dirs);
+    const u64 file_hash_table_entry_count = romfs_get_hash_table_count(num_files);
+    dir_hash_table_size = 4 * dir_hash_table_entry_count;
+    file_hash_table_size = 4 * file_hash_table_entry_count;
+
+    // Assign metadata pointers
+    RomFSHeader header{};
+
+    std::vector<u32> dir_hash_table(dir_hash_table_entry_count, ROMFS_ENTRY_EMPTY);
+    std::vector<u32> file_hash_table(file_hash_table_entry_count, ROMFS_ENTRY_EMPTY);
+
+    std::vector<u8> dir_table(dir_table_size);
+    std::vector<u8> file_table(file_table_size);
+
+    std::shared_ptr<RomFSBuildFileContext> cur_file;
+
+    // Determine file offsets.
+    u32 entry_offset = 0;
+    std::shared_ptr<RomFSBuildFileContext> prev_file = nullptr;
+    for (const auto& it : files) {
+        cur_file = it.second;
+        file_partition_size = (file_partition_size + 0xFULL) & ~0xFULL;
+        cur_file->offset = file_partition_size;
+        file_partition_size += cur_file->size;
+        cur_file->entry_offset = entry_offset;
+        entry_offset +=
+            sizeof(RomFSFileEntry) + ((cur_file->path_len - cur_file->cur_path_ofs + 3) & ~3);
+        prev_file = cur_file;
+    }
+    // Assign deferred parent/sibling ownership.
+    for (auto it = files.rbegin(); it != files.rend(); ++it) {
+        cur_file = it->second;
+        cur_file->sibling = cur_file->parent->file;
+        cur_file->parent->file = cur_file;
+    }
+
+    std::shared_ptr<RomFSBuildDirectoryContext> cur_dir;
+
+    // Determine directory offsets.
+    entry_offset = 0;
+    for (const auto& it : directories) {
+        cur_dir = it.second;
+        cur_dir->entry_offset = entry_offset;
+        entry_offset +=
+            sizeof(RomFSDirectoryEntry) + ((cur_dir->path_len - cur_dir->cur_path_ofs + 3) & ~3);
+    }
+    // Assign deferred parent/sibling ownership.
+    for (auto it = directories.rbegin(); it->second != root; ++it) {
+        cur_dir = it->second;
+        cur_dir->sibling = cur_dir->parent->child;
+        cur_dir->parent->child = cur_dir;
+    }
+
+    std::map<u64, VirtualFile> out;
+
+    // Populate file tables.
+    for (const auto& it : files) {
+        cur_file = it.second;
+        RomFSFileEntry cur_entry{};
+
+        cur_entry.parent = cur_file->parent->entry_offset;
+        cur_entry.sibling =
+            cur_file->sibling == nullptr ? ROMFS_ENTRY_EMPTY : cur_file->sibling->entry_offset;
+        cur_entry.offset = cur_file->offset;
+        cur_entry.size = cur_file->size;
+
+        const auto name_size = cur_file->path_len - cur_file->cur_path_ofs;
+        const auto hash = romfs_calc_path_hash(cur_file->parent->entry_offset, cur_file->path,
+                                               cur_file->cur_path_ofs, name_size);
+        cur_entry.hash = file_hash_table[hash % file_hash_table_entry_count];
+        file_hash_table[hash % file_hash_table_entry_count] = cur_file->entry_offset;
+
+        cur_entry.name_size = name_size;
+
+        out.emplace(cur_file->offset + ROMFS_FILEPARTITION_OFS, cur_file->source);
+        std::memcpy(file_table.data() + cur_file->entry_offset, &cur_entry, sizeof(RomFSFileEntry));
+        std::memset(file_table.data() + cur_file->entry_offset + sizeof(RomFSFileEntry), 0,
+                    (cur_entry.name_size + 3) & ~3);
+        std::memcpy(file_table.data() + cur_file->entry_offset + sizeof(RomFSFileEntry),
+                    cur_file->path.data() + cur_file->cur_path_ofs, name_size);
+    }
+
+    // Populate dir tables.
+    for (const auto& it : directories) {
+        cur_dir = it.second;
+        RomFSDirectoryEntry cur_entry{};
+
+        cur_entry.parent = cur_dir == root ? 0 : cur_dir->parent->entry_offset;
+        cur_entry.sibling =
+            cur_dir->sibling == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->sibling->entry_offset;
+        cur_entry.child =
+            cur_dir->child == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->child->entry_offset;
+        cur_entry.file = cur_dir->file == nullptr ? ROMFS_ENTRY_EMPTY : cur_dir->file->entry_offset;
+
+        const auto name_size = cur_dir->path_len - cur_dir->cur_path_ofs;
+        const auto hash = romfs_calc_path_hash(cur_dir == root ? 0 : cur_dir->parent->entry_offset,
+                                               cur_dir->path, cur_dir->cur_path_ofs, name_size);
+        cur_entry.hash = dir_hash_table[hash % dir_hash_table_entry_count];
+        dir_hash_table[hash % dir_hash_table_entry_count] = cur_dir->entry_offset;
+
+        cur_entry.name_size = name_size;
+
+        std::memcpy(dir_table.data() + cur_dir->entry_offset, &cur_entry,
+                    sizeof(RomFSDirectoryEntry));
+        std::memcpy(dir_table.data() + cur_dir->entry_offset, &cur_entry,
+                    sizeof(RomFSDirectoryEntry));
+        std::memset(dir_table.data() + cur_dir->entry_offset + sizeof(RomFSDirectoryEntry), 0,
+                    (cur_entry.name_size + 3) & ~3);
+        std::memcpy(dir_table.data() + cur_dir->entry_offset + sizeof(RomFSDirectoryEntry),
+                    cur_dir->path.data() + cur_dir->cur_path_ofs, name_size);
+    }
+
+    // Set header fields.
+    header.header_size = sizeof(RomFSHeader);
+    header.file_hash_table_size = file_hash_table_size;
+    header.file_table_size = file_table_size;
+    header.dir_hash_table_size = dir_hash_table_size;
+    header.dir_table_size = dir_table_size;
+    header.file_partition_ofs = ROMFS_FILEPARTITION_OFS;
+    header.dir_hash_table_ofs = (header.file_partition_ofs + file_partition_size + 3ULL) & ~3ULL;
+    header.dir_table_ofs = header.dir_hash_table_ofs + header.dir_hash_table_size;
+    header.file_hash_table_ofs = header.dir_table_ofs + header.dir_table_size;
+    header.file_table_ofs = header.file_hash_table_ofs + header.file_hash_table_size;
+
+    std::vector<u8> header_data(sizeof(RomFSHeader));
+    std::memcpy(header_data.data(), &header, header_data.size());
+    out.emplace(0, std::make_shared<VectorVfsFile>(header_data));
+
+    std::vector<u8> metadata(file_hash_table_size + file_table_size + dir_hash_table_size +
+                             dir_table_size);
+    std::size_t index = 0;
+    std::memcpy(metadata.data(), dir_hash_table.data(), dir_hash_table.size() * sizeof(u32));
+    index += dir_hash_table.size() * sizeof(u32);
+    std::memcpy(metadata.data() + index, dir_table.data(), dir_table.size());
+    index += dir_table.size();
+    std::memcpy(metadata.data() + index, file_hash_table.data(),
+                file_hash_table.size() * sizeof(u32));
+    index += file_hash_table.size() * sizeof(u32);
+    std::memcpy(metadata.data() + index, file_table.data(), file_table.size());
+    out.emplace(header.dir_hash_table_ofs, std::make_shared<VectorVfsFile>(metadata));
+
+    return out;
+}
+
+} // namespace FileSys
diff --git a/src/core/file_sys/fsmitm_romfsbuild.h b/src/core/file_sys/fsmitm_romfsbuild.h
new file mode 100644
index 000000000..b0c3c123b
--- /dev/null
+++ b/src/core/file_sys/fsmitm_romfsbuild.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * Adapted by DarkLordZach for use/interaction with yuzu
+ *
+ * Modifications Copyright 2018 yuzu emulator team
+ * Licensed under GPLv2 or any later version
+ * Refer to the license.txt file included.
+ */
+
+#pragma once
+
+#include <map>
+#include <memory>
+#include <string>
+#include <boost/detail/container_fwd.hpp>
+#include "common/common_types.h"
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+struct RomFSBuildDirectoryContext;
+struct RomFSBuildFileContext;
+struct RomFSDirectoryEntry;
+struct RomFSFileEntry;
+
+class RomFSBuildContext {
+public:
+    explicit RomFSBuildContext(VirtualDir base);
+    ~RomFSBuildContext();
+
+    // This finalizes the context.
+    std::map<u64, VirtualFile> Build();
+
+private:
+    VirtualDir base;
+    std::shared_ptr<RomFSBuildDirectoryContext> root;
+    std::map<std::string, std::shared_ptr<RomFSBuildDirectoryContext>, std::less<>> directories;
+    std::map<std::string, std::shared_ptr<RomFSBuildFileContext>, std::less<>> files;
+    u64 num_dirs = 0;
+    u64 num_files = 0;
+    u64 dir_table_size = 0;
+    u64 file_table_size = 0;
+    u64 dir_hash_table_size = 0;
+    u64 file_hash_table_size = 0;
+    u64 file_partition_size = 0;
+
+    void VisitDirectory(VirtualDir filesys, std::shared_ptr<RomFSBuildDirectoryContext> parent);
+
+    bool AddDirectory(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                      std::shared_ptr<RomFSBuildDirectoryContext> dir_ctx);
+    bool AddFile(std::shared_ptr<RomFSBuildDirectoryContext> parent_dir_ctx,
+                 std::shared_ptr<RomFSBuildFileContext> file_ctx);
+};
+
+} // namespace FileSys
diff --git a/src/core/file_sys/patch_manager.cpp b/src/core/file_sys/patch_manager.cpp
index aebc69d52..4b3b5e665 100644
--- a/src/core/file_sys/patch_manager.cpp
+++ b/src/core/file_sys/patch_manager.cpp
@@ -11,6 +11,7 @@
 #include "core/file_sys/patch_manager.h"
 #include "core/file_sys/registered_cache.h"
 #include "core/file_sys/romfs.h"
+#include "core/file_sys/vfs_layered.h"
 #include "core/hle/service/filesystem/filesystem.h"
 #include "core/loader/loader.h"
 
@@ -31,8 +32,9 @@ std::string FormatTitleVersion(u32 version, TitleVersionFormat format) {
     return fmt::format("v{}.{}.{}", bytes[3], bytes[2], bytes[1]);
 }
 
-constexpr std::array<const char*, 1> PATCH_TYPE_NAMES{
+constexpr std::array<const char*, 2> PATCH_TYPE_NAMES{
     "Update",
+    "LayeredFS",
 };
 
 std::string FormatPatchTypeName(PatchType type) {
@@ -66,6 +68,44 @@ VirtualDir PatchManager::PatchExeFS(VirtualDir exefs) const {
     return exefs;
 }
 
+static void ApplyLayeredFS(VirtualFile& romfs, u64 title_id, ContentRecordType type) {
+    const auto load_dir = Service::FileSystem::GetModificationLoadRoot(title_id);
+    if (type != ContentRecordType::Program || load_dir == nullptr || load_dir->GetSize() <= 0) {
+        return;
+    }
+
+    auto extracted = ExtractRomFS(romfs);
+    if (extracted == nullptr) {
+        return;
+    }
+
+    auto patch_dirs = load_dir->GetSubdirectories();
+    std::sort(patch_dirs.begin(), patch_dirs.end(),
+              [](const VirtualDir& l, const VirtualDir& r) { return l->GetName() < r->GetName(); });
+
+    std::vector<VirtualDir> layers;
+    layers.reserve(patch_dirs.size() + 1);
+    for (const auto& subdir : patch_dirs) {
+        auto romfs_dir = subdir->GetSubdirectory("romfs");
+        if (romfs_dir != nullptr)
+            layers.push_back(std::move(romfs_dir));
+    }
+    layers.push_back(std::move(extracted));
+
+    auto layered = LayeredVfsDirectory::MakeLayeredDirectory(std::move(layers));
+    if (layered == nullptr) {
+        return;
+    }
+
+    auto packed = CreateRomFS(std::move(layered));
+    if (packed == nullptr) {
+        return;
+    }
+
+    LOG_INFO(Loader, "    RomFS: LayeredFS patches applied successfully");
+    romfs = std::move(packed);
+}
+
 VirtualFile PatchManager::PatchRomFS(VirtualFile romfs, u64 ivfc_offset,
                                      ContentRecordType type) const {
     LOG_INFO(Loader, "Patching RomFS for title_id={:016X}, type={:02X}", title_id,
@@ -89,6 +129,9 @@ VirtualFile PatchManager::PatchRomFS(VirtualFile romfs, u64 ivfc_offset,
         }
     }
 
+    // LayeredFS
+    ApplyLayeredFS(romfs, title_id, type);
+
     return romfs;
 }
 
@@ -114,6 +157,10 @@ std::map<PatchType, std::string> PatchManager::GetPatchVersionNames() const {
         }
     }
 
+    const auto lfs_dir = Service::FileSystem::GetModificationLoadRoot(title_id);
+    if (lfs_dir != nullptr && lfs_dir->GetSize() > 0)
+        out.insert_or_assign(PatchType::LayeredFS, "");
+
     return out;
 }
 
diff --git a/src/core/file_sys/patch_manager.h b/src/core/file_sys/patch_manager.h
index 209cab1dc..464f17515 100644
--- a/src/core/file_sys/patch_manager.h
+++ b/src/core/file_sys/patch_manager.h
@@ -26,6 +26,7 @@ std::string FormatTitleVersion(u32 version,
 
 enum class PatchType {
     Update,
+    LayeredFS,
 };
 
 std::string FormatPatchTypeName(PatchType type);
@@ -42,6 +43,7 @@ public:
 
     // Currently tracked RomFS patches:
     // - Game Updates
+    // - LayeredFS
     VirtualFile PatchRomFS(VirtualFile base, u64 ivfc_offset,
                            ContentRecordType type = ContentRecordType::Program) const;
 
diff --git a/src/core/file_sys/registered_cache.cpp b/src/core/file_sys/registered_cache.cpp
index dad7ae10b..e9b040689 100644
--- a/src/core/file_sys/registered_cache.cpp
+++ b/src/core/file_sys/registered_cache.cpp
@@ -18,6 +18,10 @@
 #include "core/loader/loader.h"
 
 namespace FileSys {
+
+// The size of blocks to use when vfs raw copying into nand.
+constexpr size_t VFS_RC_LARGE_COPY_BLOCK = 0x400000;
+
 std::string RegisteredCacheEntry::DebugInfo() const {
     return fmt::format("title_id={:016X}, content_type={:02X}", title_id, static_cast<u8>(type));
 }
@@ -121,7 +125,7 @@ VirtualFile RegisteredCache::OpenFileOrDirectoryConcat(const VirtualDir& dir,
             if (concat.empty())
                 return nullptr;
 
-            file = FileSys::ConcatenateFiles(concat);
+            file = ConcatenatedVfsFile::MakeConcatenatedFile(concat, concat.front()->GetName());
         }
 
         return file;
@@ -480,7 +484,8 @@ InstallResult RegisteredCache::RawInstallNCA(std::shared_ptr<NCA> nca, const Vfs
     auto out = dir->CreateFileRelative(path);
     if (out == nullptr)
         return InstallResult::ErrorCopyFailed;
-    return copy(in, out) ? InstallResult::Success : InstallResult::ErrorCopyFailed;
+    return copy(in, out, VFS_RC_LARGE_COPY_BLOCK) ? InstallResult::Success
+                                                  : InstallResult::ErrorCopyFailed;
 }
 
 bool RegisteredCache::RawInstallYuzuMeta(const CNMT& cnmt) {
diff --git a/src/core/file_sys/registered_cache.h b/src/core/file_sys/registered_cache.h
index f487b0cf0..c0cd59fc5 100644
--- a/src/core/file_sys/registered_cache.h
+++ b/src/core/file_sys/registered_cache.h
@@ -27,7 +27,7 @@ struct ContentRecord;
 
 using NcaID = std::array<u8, 0x10>;
 using RegisteredCacheParsingFunction = std::function<VirtualFile(const VirtualFile&, const NcaID&)>;
-using VfsCopyFunction = std::function<bool(VirtualFile, VirtualFile)>;
+using VfsCopyFunction = std::function<bool(const VirtualFile&, const VirtualFile&, size_t)>;
 
 enum class InstallResult {
     Success,
diff --git a/src/core/file_sys/romfs.cpp b/src/core/file_sys/romfs.cpp
index 9f6e41cdf..5910f7046 100644
--- a/src/core/file_sys/romfs.cpp
+++ b/src/core/file_sys/romfs.cpp
@@ -4,8 +4,10 @@
 
 #include "common/common_types.h"
 #include "common/swap.h"
+#include "core/file_sys/fsmitm_romfsbuild.h"
 #include "core/file_sys/romfs.h"
 #include "core/file_sys/vfs.h"
+#include "core/file_sys/vfs_concat.h"
 #include "core/file_sys/vfs_offset.h"
 #include "core/file_sys/vfs_vector.h"
 
@@ -98,7 +100,7 @@ void ProcessDirectory(VirtualFile file, std::size_t dir_offset, std::size_t file
     }
 }
 
-VirtualDir ExtractRomFS(VirtualFile file) {
+VirtualDir ExtractRomFS(VirtualFile file, RomFSExtractionType type) {
     RomFSHeader header{};
     if (file->ReadObject(&header) != sizeof(RomFSHeader))
         return nullptr;
@@ -117,9 +119,22 @@ VirtualDir ExtractRomFS(VirtualFile file) {
 
     VirtualDir out = std::move(root);
 
-    while (out->GetSubdirectory("") != nullptr)
-        out = out->GetSubdirectory("");
+    while (out->GetSubdirectories().size() == 1 && out->GetFiles().empty()) {
+        if (out->GetSubdirectories().front()->GetName() == "data" &&
+            type == RomFSExtractionType::Truncated)
+            break;
+        out = out->GetSubdirectories().front();
+    }
 
     return out;
 }
+
+VirtualFile CreateRomFS(VirtualDir dir) {
+    if (dir == nullptr)
+        return nullptr;
+
+    RomFSBuildContext ctx{dir};
+    return ConcatenatedVfsFile::MakeConcatenatedFile(0, ctx.Build(), dir->GetName());
+}
+
 } // namespace FileSys
diff --git a/src/core/file_sys/romfs.h b/src/core/file_sys/romfs.h
index e54a7d7a9..ecd1eb725 100644
--- a/src/core/file_sys/romfs.h
+++ b/src/core/file_sys/romfs.h
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <array>
+#include <map>
 #include "common/common_funcs.h"
 #include "common/common_types.h"
 #include "common/swap.h"
@@ -12,6 +13,8 @@
 
 namespace FileSys {
 
+struct RomFSHeader;
+
 struct IVFCLevel {
     u64_le offset;
     u64_le size;
@@ -29,8 +32,18 @@ struct IVFCHeader {
 };
 static_assert(sizeof(IVFCHeader) == 0xE0, "IVFCHeader has incorrect size.");
 
+enum class RomFSExtractionType {
+    Full,      // Includes data directory
+    Truncated, // Traverses into data directory
+};
+
 // Converts a RomFS binary blob to VFS Filesystem
 // Returns nullptr on failure
-VirtualDir ExtractRomFS(VirtualFile file);
+VirtualDir ExtractRomFS(VirtualFile file,
+                        RomFSExtractionType type = RomFSExtractionType::Truncated);
+
+// Converts a VFS filesystem into a RomFS binary
+// Returns nullptr on failure
+VirtualFile CreateRomFS(VirtualDir dir);
 
 } // namespace FileSys
diff --git a/src/core/file_sys/vfs.cpp b/src/core/file_sys/vfs.cpp
index d7b52abfd..bfe50da73 100644
--- a/src/core/file_sys/vfs.cpp
+++ b/src/core/file_sys/vfs.cpp
@@ -399,6 +399,15 @@ bool VfsDirectory::Copy(std::string_view src, std::string_view dest) {
     return f2->WriteBytes(f1->ReadAllBytes()) == f1->GetSize();
 }
 
+std::map<std::string, VfsEntryType, std::less<>> VfsDirectory::GetEntries() const {
+    std::map<std::string, VfsEntryType, std::less<>> out;
+    for (const auto& dir : GetSubdirectories())
+        out.emplace(dir->GetName(), VfsEntryType::Directory);
+    for (const auto& file : GetFiles())
+        out.emplace(file->GetName(), VfsEntryType::File);
+    return out;
+}
+
 std::string VfsDirectory::GetFullPath() const {
     if (IsRoot())
         return GetName();
@@ -454,13 +463,41 @@ bool DeepEquals(const VirtualFile& file1, const VirtualFile& file2, std::size_t
     return true;
 }
 
-bool VfsRawCopy(VirtualFile src, VirtualFile dest) {
-    if (src == nullptr || dest == nullptr)
+bool VfsRawCopy(const VirtualFile& src, const VirtualFile& dest, std::size_t block_size) {
+    if (src == nullptr || dest == nullptr || !src->IsReadable() || !dest->IsWritable())
         return false;
     if (!dest->Resize(src->GetSize()))
         return false;
-    std::vector<u8> data = src->ReadAllBytes();
-    return dest->WriteBytes(data, 0) == data.size();
+
+    std::vector<u8> temp(std::min(block_size, src->GetSize()));
+    for (std::size_t i = 0; i < src->GetSize(); i += block_size) {
+        const auto read = std::min(block_size, src->GetSize() - i);
+        const auto block = src->Read(temp.data(), read, i);
+
+        if (dest->Write(temp.data(), read, i) != read)
+            return false;
+    }
+
+    return true;
+}
+
+bool VfsRawCopyD(const VirtualDir& src, const VirtualDir& dest, std::size_t block_size) {
+    if (src == nullptr || dest == nullptr || !src->IsReadable() || !dest->IsWritable())
+        return false;
+
+    for (const auto& file : src->GetFiles()) {
+        const auto out = dest->CreateFile(file->GetName());
+        if (!VfsRawCopy(file, out, block_size))
+            return false;
+    }
+
+    for (const auto& dir : src->GetSubdirectories()) {
+        const auto out = dest->CreateSubdirectory(dir->GetName());
+        if (!VfsRawCopyD(dir, out, block_size))
+            return false;
+    }
+
+    return true;
 }
 
 VirtualDir GetOrCreateDirectoryRelative(const VirtualDir& rel, std::string_view path) {
diff --git a/src/core/file_sys/vfs.h b/src/core/file_sys/vfs.h
index 74489b452..270291631 100644
--- a/src/core/file_sys/vfs.h
+++ b/src/core/file_sys/vfs.h
@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <map>
 #include <memory>
 #include <string>
 #include <string_view>
@@ -265,6 +266,10 @@ public:
     // dest.
     virtual bool Copy(std::string_view src, std::string_view dest);
 
+    // Gets all of the entries directly in the directory (files and dirs), returning a map between
+    // item name -> type.
+    virtual std::map<std::string, VfsEntryType, std::less<>> GetEntries() const;
+
     // Interprets the file with name file instead as a directory of type directory.
     // The directory must have a constructor that takes a single argument of type
     // std::shared_ptr<VfsFile>. Allows to reinterpret container files (i.e NCA, zip, XCI, etc) as a
@@ -310,13 +315,19 @@ public:
     bool Rename(std::string_view name) override;
 };
 
-// Compare the two files, byte-for-byte, in increments specificed by block_size
-bool DeepEquals(const VirtualFile& file1, const VirtualFile& file2, std::size_t block_size = 0x200);
+// Compare the two files, byte-for-byte, in increments specified by block_size
+bool DeepEquals(const VirtualFile& file1, const VirtualFile& file2,
+                std::size_t block_size = 0x1000);
 
 // A method that copies the raw data between two different implementations of VirtualFile. If you
 // are using the same implementation, it is probably better to use the Copy method in the parent
 // directory of src/dest.
-bool VfsRawCopy(VirtualFile src, VirtualFile dest);
+bool VfsRawCopy(const VirtualFile& src, const VirtualFile& dest, std::size_t block_size = 0x1000);
+
+// A method that performs a similar function to VfsRawCopy above, but instead copies entire
+// directories. It suffers the same performance penalties as above and an implementation-specific
+// Copy should always be preferred.
+bool VfsRawCopyD(const VirtualDir& src, const VirtualDir& dest, std::size_t block_size = 0x1000);
 
 // Checks if the directory at path relative to rel exists. If it does, returns that. If it does not
 // it attempts to create it and returns the new dir or nullptr on failure.
diff --git a/src/core/file_sys/vfs_concat.cpp b/src/core/file_sys/vfs_concat.cpp
index dc7a279a9..16d801c0c 100644
--- a/src/core/file_sys/vfs_concat.cpp
+++ b/src/core/file_sys/vfs_concat.cpp
@@ -5,17 +5,22 @@
 #include <algorithm>
 #include <utility>
 
+#include "common/assert.h"
 #include "core/file_sys/vfs_concat.h"
+#include "core/file_sys/vfs_static.h"
 
 namespace FileSys {
 
-VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name) {
-    if (files.empty())
-        return nullptr;
-    if (files.size() == 1)
-        return files[0];
+static bool VerifyConcatenationMapContinuity(const std::map<u64, VirtualFile>& map) {
+    const auto last_valid = --map.end();
+    for (auto iter = map.begin(); iter != last_valid;) {
+        const auto old = iter++;
+        if (old->first + old->second->GetSize() != iter->first) {
+            return false;
+        }
+    }
 
-    return std::shared_ptr<VfsFile>(new ConcatenatedVfsFile(std::move(files), std::move(name)));
+    return map.begin()->first == 0;
 }
 
 ConcatenatedVfsFile::ConcatenatedVfsFile(std::vector<VirtualFile> files_, std::string name)
@@ -27,8 +32,48 @@ ConcatenatedVfsFile::ConcatenatedVfsFile(std::vector<VirtualFile> files_, std::s
     }
 }
 
+ConcatenatedVfsFile::ConcatenatedVfsFile(std::map<u64, VirtualFile> files_, std::string name)
+    : files(std::move(files_)), name(std::move(name)) {
+    ASSERT(VerifyConcatenationMapContinuity(files));
+}
+
 ConcatenatedVfsFile::~ConcatenatedVfsFile() = default;
 
+VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(std::vector<VirtualFile> files,
+                                                      std::string name) {
+    if (files.empty())
+        return nullptr;
+    if (files.size() == 1)
+        return files[0];
+
+    return std::shared_ptr<VfsFile>(new ConcatenatedVfsFile(std::move(files), std::move(name)));
+}
+
+VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(u8 filler_byte,
+                                                      std::map<u64, VirtualFile> files,
+                                                      std::string name) {
+    if (files.empty())
+        return nullptr;
+    if (files.size() == 1)
+        return files.begin()->second;
+
+    const auto last_valid = --files.end();
+    for (auto iter = files.begin(); iter != last_valid;) {
+        const auto old = iter++;
+        if (old->first + old->second->GetSize() != iter->first) {
+            files.emplace(old->first + old->second->GetSize(),
+                          std::make_shared<StaticVfsFile>(filler_byte, iter->first - old->first -
+                                                                           old->second->GetSize()));
+        }
+    }
+
+    // Ensure the map starts at offset 0 (start of file), otherwise pad to fill.
+    if (files.begin()->first != 0)
+        files.emplace(0, std::make_shared<StaticVfsFile>(filler_byte, files.begin()->first));
+
+    return std::shared_ptr<VfsFile>(new ConcatenatedVfsFile(std::move(files), std::move(name)));
+}
+
 std::string ConcatenatedVfsFile::GetName() const {
     if (files.empty())
         return "";
@@ -62,7 +107,7 @@ bool ConcatenatedVfsFile::IsReadable() const {
 }
 
 std::size_t ConcatenatedVfsFile::Read(u8* data, std::size_t length, std::size_t offset) const {
-    auto entry = files.end();
+    auto entry = --files.end();
     for (auto iter = files.begin(); iter != files.end(); ++iter) {
         if (iter->first > offset) {
             entry = --iter;
@@ -70,20 +115,17 @@ std::size_t ConcatenatedVfsFile::Read(u8* data, std::size_t length, std::size_t
         }
     }
 
-    // Check if the entry should be the last one. The loop above will make it end().
-    if (entry == files.end() && offset < files.rbegin()->first + files.rbegin()->second->GetSize())
-        --entry;
-
-    if (entry == files.end())
+    if (entry->first + entry->second->GetSize() <= offset)
         return 0;
 
-    const auto remaining = entry->second->GetSize() + offset - entry->first;
-    if (length > remaining) {
-        return entry->second->Read(data, remaining, offset - entry->first) +
-               Read(data + remaining, length - remaining, offset + remaining);
+    const auto read_in =
+        std::min<u64>(entry->first + entry->second->GetSize() - offset, entry->second->GetSize());
+    if (length > read_in) {
+        return entry->second->Read(data, read_in, offset - entry->first) +
+               Read(data + read_in, length - read_in, offset + read_in);
     }
 
-    return entry->second->Read(data, length, offset - entry->first);
+    return entry->second->Read(data, std::min<u64>(read_in, length), offset - entry->first);
 }
 
 std::size_t ConcatenatedVfsFile::Write(const u8* data, std::size_t length, std::size_t offset) {
@@ -93,4 +135,5 @@ std::size_t ConcatenatedVfsFile::Write(const u8* data, std::size_t length, std::
 bool ConcatenatedVfsFile::Rename(std::string_view name) {
     return false;
 }
+
 } // namespace FileSys
diff --git a/src/core/file_sys/vfs_concat.h b/src/core/file_sys/vfs_concat.h
index 717d04bdc..c90f9d5d1 100644
--- a/src/core/file_sys/vfs_concat.h
+++ b/src/core/file_sys/vfs_concat.h
@@ -4,26 +4,30 @@
 
 #pragma once
 
+#include <map>
 #include <memory>
 #include <string_view>
-#include <boost/container/flat_map.hpp>
 #include "core/file_sys/vfs.h"
 
 namespace FileSys {
 
-// Wrapper function to allow for more efficient handling of files.size() == 0, 1 cases.
-VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name = "");
-
 // Class that wraps multiple vfs files and concatenates them, making reads seamless. Currently
 // read-only.
 class ConcatenatedVfsFile : public VfsFile {
-    friend VirtualFile ConcatenateFiles(std::vector<VirtualFile> files, std::string name);
-
     ConcatenatedVfsFile(std::vector<VirtualFile> files, std::string name);
+    ConcatenatedVfsFile(std::map<u64, VirtualFile> files, std::string name);
 
 public:
     ~ConcatenatedVfsFile() override;
 
+    /// Wrapper function to allow for more efficient handling of files.size() == 0, 1 cases.
+    static VirtualFile MakeConcatenatedFile(std::vector<VirtualFile> files, std::string name);
+
+    /// Convenience function that turns a map of offsets to files into a concatenated file, filling
+    /// gaps with a given filler byte.
+    static VirtualFile MakeConcatenatedFile(u8 filler_byte, std::map<u64, VirtualFile> files,
+                                            std::string name);
+
     std::string GetName() const override;
     std::size_t GetSize() const override;
     bool Resize(std::size_t new_size) override;
@@ -36,7 +40,7 @@ public:
 
 private:
     // Maps starting offset to file -- more efficient.
-    boost::container::flat_map<u64, VirtualFile> files;
+    std::map<u64, VirtualFile> files;
     std::string name;
 };
 
diff --git a/src/core/file_sys/vfs_layered.cpp b/src/core/file_sys/vfs_layered.cpp
new file mode 100644
index 000000000..bfee01725
--- /dev/null
+++ b/src/core/file_sys/vfs_layered.cpp
@@ -0,0 +1,132 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <utility>
+#include "core/file_sys/vfs_layered.h"
+
+namespace FileSys {
+
+LayeredVfsDirectory::LayeredVfsDirectory(std::vector<VirtualDir> dirs, std::string name)
+    : dirs(std::move(dirs)), name(std::move(name)) {}
+
+LayeredVfsDirectory::~LayeredVfsDirectory() = default;
+
+VirtualDir LayeredVfsDirectory::MakeLayeredDirectory(std::vector<VirtualDir> dirs,
+                                                     std::string name) {
+    if (dirs.empty())
+        return nullptr;
+    if (dirs.size() == 1)
+        return dirs[0];
+
+    return std::shared_ptr<VfsDirectory>(new LayeredVfsDirectory(std::move(dirs), std::move(name)));
+}
+
+std::shared_ptr<VfsFile> LayeredVfsDirectory::GetFileRelative(std::string_view path) const {
+    for (const auto& layer : dirs) {
+        const auto file = layer->GetFileRelative(path);
+        if (file != nullptr)
+            return file;
+    }
+
+    return nullptr;
+}
+
+std::shared_ptr<VfsDirectory> LayeredVfsDirectory::GetDirectoryRelative(
+    std::string_view path) const {
+    std::vector<VirtualDir> out;
+    for (const auto& layer : dirs) {
+        auto dir = layer->GetDirectoryRelative(path);
+        if (dir != nullptr)
+            out.push_back(std::move(dir));
+    }
+
+    return MakeLayeredDirectory(std::move(out));
+}
+
+std::shared_ptr<VfsFile> LayeredVfsDirectory::GetFile(std::string_view name) const {
+    return GetFileRelative(name);
+}
+
+std::shared_ptr<VfsDirectory> LayeredVfsDirectory::GetSubdirectory(std::string_view name) const {
+    return GetDirectoryRelative(name);
+}
+
+std::string LayeredVfsDirectory::GetFullPath() const {
+    return dirs[0]->GetFullPath();
+}
+
+std::vector<std::shared_ptr<VfsFile>> LayeredVfsDirectory::GetFiles() const {
+    std::vector<VirtualFile> out;
+    for (const auto& layer : dirs) {
+        for (const auto& file : layer->GetFiles()) {
+            if (std::find_if(out.begin(), out.end(), [&file](const VirtualFile& comp) {
+                    return comp->GetName() == file->GetName();
+                }) == out.end()) {
+                out.push_back(file);
+            }
+        }
+    }
+
+    return out;
+}
+
+std::vector<std::shared_ptr<VfsDirectory>> LayeredVfsDirectory::GetSubdirectories() const {
+    std::vector<std::string> names;
+    for (const auto& layer : dirs) {
+        for (const auto& sd : layer->GetSubdirectories()) {
+            if (std::find(names.begin(), names.end(), sd->GetName()) == names.end())
+                names.push_back(sd->GetName());
+        }
+    }
+
+    std::vector<VirtualDir> out;
+    out.reserve(names.size());
+    for (const auto& subdir : names)
+        out.push_back(GetSubdirectory(subdir));
+
+    return out;
+}
+
+bool LayeredVfsDirectory::IsWritable() const {
+    return false;
+}
+
+bool LayeredVfsDirectory::IsReadable() const {
+    return true;
+}
+
+std::string LayeredVfsDirectory::GetName() const {
+    return name.empty() ? dirs[0]->GetName() : name;
+}
+
+std::shared_ptr<VfsDirectory> LayeredVfsDirectory::GetParentDirectory() const {
+    return dirs[0]->GetParentDirectory();
+}
+
+std::shared_ptr<VfsDirectory> LayeredVfsDirectory::CreateSubdirectory(std::string_view name) {
+    return nullptr;
+}
+
+std::shared_ptr<VfsFile> LayeredVfsDirectory::CreateFile(std::string_view name) {
+    return nullptr;
+}
+
+bool LayeredVfsDirectory::DeleteSubdirectory(std::string_view name) {
+    return false;
+}
+
+bool LayeredVfsDirectory::DeleteFile(std::string_view name) {
+    return false;
+}
+
+bool LayeredVfsDirectory::Rename(std::string_view name_) {
+    name = name_;
+    return true;
+}
+
+bool LayeredVfsDirectory::ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) {
+    return false;
+}
+} // namespace FileSys
diff --git a/src/core/file_sys/vfs_layered.h b/src/core/file_sys/vfs_layered.h
new file mode 100644
index 000000000..d85310f57
--- /dev/null
+++ b/src/core/file_sys/vfs_layered.h
@@ -0,0 +1,50 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+// Class that stacks multiple VfsDirectories on top of each other, attempting to read from the first
+// one and falling back to the one after. The highest priority directory (overwrites all others)
+// should be element 0 in the dirs vector.
+class LayeredVfsDirectory : public VfsDirectory {
+    LayeredVfsDirectory(std::vector<VirtualDir> dirs, std::string name);
+
+public:
+    ~LayeredVfsDirectory() override;
+
+    /// Wrapper function to allow for more efficient handling of dirs.size() == 0, 1 cases.
+    static VirtualDir MakeLayeredDirectory(std::vector<VirtualDir> dirs, std::string name = "");
+
+    std::shared_ptr<VfsFile> GetFileRelative(std::string_view path) const override;
+    std::shared_ptr<VfsDirectory> GetDirectoryRelative(std::string_view path) const override;
+    std::shared_ptr<VfsFile> GetFile(std::string_view name) const override;
+    std::shared_ptr<VfsDirectory> GetSubdirectory(std::string_view name) const override;
+    std::string GetFullPath() const override;
+
+    std::vector<std::shared_ptr<VfsFile>> GetFiles() const override;
+    std::vector<std::shared_ptr<VfsDirectory>> GetSubdirectories() const override;
+    bool IsWritable() const override;
+    bool IsReadable() const override;
+    std::string GetName() const override;
+    std::shared_ptr<VfsDirectory> GetParentDirectory() const override;
+    std::shared_ptr<VfsDirectory> CreateSubdirectory(std::string_view name) override;
+    std::shared_ptr<VfsFile> CreateFile(std::string_view name) override;
+    bool DeleteSubdirectory(std::string_view name) override;
+    bool DeleteFile(std::string_view name) override;
+    bool Rename(std::string_view name) override;
+
+protected:
+    bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
+
+private:
+    std::vector<VirtualDir> dirs;
+    std::string name;
+};
+
+} // namespace FileSys
diff --git a/src/core/file_sys/vfs_real.cpp b/src/core/file_sys/vfs_real.cpp
index 5e242e20f..9defad04c 100644
--- a/src/core/file_sys/vfs_real.cpp
+++ b/src/core/file_sys/vfs_real.cpp
@@ -413,6 +413,23 @@ std::string RealVfsDirectory::GetFullPath() const {
     return out;
 }
 
+std::map<std::string, VfsEntryType, std::less<>> RealVfsDirectory::GetEntries() const {
+    if (perms == Mode::Append)
+        return {};
+
+    std::map<std::string, VfsEntryType, std::less<>> out;
+    FileUtil::ForeachDirectoryEntry(
+        nullptr, path,
+        [&out](u64* entries_out, const std::string& directory, const std::string& filename) {
+            const std::string full_path = directory + DIR_SEP + filename;
+            out.emplace(filename, FileUtil::IsDirectory(full_path) ? VfsEntryType::Directory
+                                                                   : VfsEntryType::File);
+            return true;
+        });
+
+    return out;
+}
+
 bool RealVfsDirectory::ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) {
     return false;
 }
diff --git a/src/core/file_sys/vfs_real.h b/src/core/file_sys/vfs_real.h
index 681c43e82..5b61db90d 100644
--- a/src/core/file_sys/vfs_real.h
+++ b/src/core/file_sys/vfs_real.h
@@ -98,6 +98,7 @@ public:
     bool DeleteFile(std::string_view name) override;
     bool Rename(std::string_view name) override;
     std::string GetFullPath() const override;
+    std::map<std::string, VfsEntryType, std::less<>> GetEntries() const override;
 
 protected:
     bool ReplaceFileWithSubdirectory(VirtualFile file, VirtualDir dir) override;
diff --git a/src/core/file_sys/vfs_static.h b/src/core/file_sys/vfs_static.h
new file mode 100644
index 000000000..44fab51d1
--- /dev/null
+++ b/src/core/file_sys/vfs_static.h
@@ -0,0 +1,79 @@
+// Copyright 2018 yuzu emulator team
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <algorithm>
+#include <memory>
+#include <string_view>
+
+#include "core/file_sys/vfs.h"
+
+namespace FileSys {
+
+class StaticVfsFile : public VfsFile {
+public:
+    explicit StaticVfsFile(u8 value, std::size_t size = 0, std::string name = "",
+                           VirtualDir parent = nullptr)
+        : value{value}, size{size}, name{std::move(name)}, parent{std::move(parent)} {}
+
+    std::string GetName() const override {
+        return name;
+    }
+
+    std::size_t GetSize() const override {
+        return size;
+    }
+
+    bool Resize(std::size_t new_size) override {
+        size = new_size;
+        return true;
+    }
+
+    std::shared_ptr<VfsDirectory> GetContainingDirectory() const override {
+        return parent;
+    }
+
+    bool IsWritable() const override {
+        return false;
+    }
+
+    bool IsReadable() const override {
+        return true;
+    }
+
+    std::size_t Read(u8* data, std::size_t length, std::size_t offset) const override {
+        const auto read = std::min(length, size - offset);
+        std::fill(data, data + read, value);
+        return read;
+    }
+
+    std::size_t Write(const u8* data, std::size_t length, std::size_t offset) override {
+        return 0;
+    }
+
+    boost::optional<u8> ReadByte(std::size_t offset) const override {
+        if (offset < size)
+            return value;
+        return boost::none;
+    }
+
+    std::vector<u8> ReadBytes(std::size_t length, std::size_t offset) const override {
+        const auto read = std::min(length, size - offset);
+        return std::vector<u8>(read, value);
+    }
+
+    bool Rename(std::string_view new_name) override {
+        name = new_name;
+        return true;
+    }
+
+private:
+    u8 value;
+    std::size_t size;
+    std::string name;
+    VirtualDir parent;
+};
+
+} // namespace FileSys
diff --git a/src/core/file_sys/vfs_vector.cpp b/src/core/file_sys/vfs_vector.cpp
index ec7f735b5..389c7e003 100644
--- a/src/core/file_sys/vfs_vector.cpp
+++ b/src/core/file_sys/vfs_vector.cpp
@@ -3,10 +3,64 @@
 // Refer to the license.txt file included.
 
 #include <algorithm>
+#include <cstring>
 #include <utility>
 #include "core/file_sys/vfs_vector.h"
 
 namespace FileSys {
+VectorVfsFile::VectorVfsFile(std::vector<u8> initial_data, std::string name, VirtualDir parent)
+    : data(std::move(initial_data)), parent(std::move(parent)), name(std::move(name)) {}
+
+VectorVfsFile::~VectorVfsFile() = default;
+
+std::string VectorVfsFile::GetName() const {
+    return name;
+}
+
+size_t VectorVfsFile::GetSize() const {
+    return data.size();
+}
+
+bool VectorVfsFile::Resize(size_t new_size) {
+    data.resize(new_size);
+    return true;
+}
+
+std::shared_ptr<VfsDirectory> VectorVfsFile::GetContainingDirectory() const {
+    return parent;
+}
+
+bool VectorVfsFile::IsWritable() const {
+    return true;
+}
+
+bool VectorVfsFile::IsReadable() const {
+    return true;
+}
+
+std::size_t VectorVfsFile::Read(u8* data_, std::size_t length, std::size_t offset) const {
+    const auto read = std::min(length, data.size() - offset);
+    std::memcpy(data_, data.data() + offset, read);
+    return read;
+}
+
+std::size_t VectorVfsFile::Write(const u8* data_, std::size_t length, std::size_t offset) {
+    if (offset + length > data.size())
+        data.resize(offset + length);
+    const auto write = std::min(length, data.size() - offset);
+    std::memcpy(data.data(), data_, write);
+    return write;
+}
+
+bool VectorVfsFile::Rename(std::string_view name_) {
+    name = name_;
+    return true;
+}
+
+void VectorVfsFile::Assign(std::vector<u8> new_data) {
+    data = std::move(new_data);
+}
+
 VectorVfsDirectory::VectorVfsDirectory(std::vector<VirtualFile> files_,
                                        std::vector<VirtualDir> dirs_, std::string name_,
                                        VirtualDir parent_)
diff --git a/src/core/file_sys/vfs_vector.h b/src/core/file_sys/vfs_vector.h
index cba44a7a6..48a414c98 100644
--- a/src/core/file_sys/vfs_vector.h
+++ b/src/core/file_sys/vfs_vector.h
@@ -8,6 +8,31 @@
 
 namespace FileSys {
 
+// An implementation of VfsFile that is backed by a vector optionally supplied upon construction
+class VectorVfsFile : public VfsFile {
+public:
+    explicit VectorVfsFile(std::vector<u8> initial_data = {}, std::string name = "",
+                           VirtualDir parent = nullptr);
+    ~VectorVfsFile() override;
+
+    std::string GetName() const override;
+    std::size_t GetSize() const override;
+    bool Resize(std::size_t new_size) override;
+    std::shared_ptr<VfsDirectory> GetContainingDirectory() const override;
+    bool IsWritable() const override;
+    bool IsReadable() const override;
+    std::size_t Read(u8* data, std::size_t length, std::size_t offset) const override;
+    std::size_t Write(const u8* data, std::size_t length, std::size_t offset) override;
+    bool Rename(std::string_view name) override;
+
+    virtual void Assign(std::vector<u8> new_data);
+
+private:
+    std::vector<u8> data;
+    VirtualDir parent;
+    std::string name;
+};
+
 // An implementation of VfsDirectory that maintains two vectors for subdirectories and files.
 // Vector data is supplied upon construction.
 class VectorVfsDirectory : public VfsDirectory {
diff --git a/src/core/hle/service/filesystem/filesystem.cpp b/src/core/hle/service/filesystem/filesystem.cpp
index d349ee686..aed2abb71 100644
--- a/src/core/hle/service/filesystem/filesystem.cpp
+++ b/src/core/hle/service/filesystem/filesystem.cpp
@@ -343,6 +343,15 @@ std::shared_ptr<FileSys::RegisteredCache> GetSDMCContents() {
     return sdmc_factory->GetSDMCContents();
 }
 
+FileSys::VirtualDir GetModificationLoadRoot(u64 title_id) {
+    LOG_TRACE(Service_FS, "Opening mod load root for tid={:016X}", title_id);
+
+    if (bis_factory == nullptr)
+        return nullptr;
+
+    return bis_factory->GetModificationLoadRoot(title_id);
+}
+
 void CreateFactories(const FileSys::VirtualFilesystem& vfs, bool overwrite) {
     if (overwrite) {
         bis_factory = nullptr;
@@ -354,9 +363,11 @@ void CreateFactories(const FileSys::VirtualFilesystem& vfs, bool overwrite) {
                                              FileSys::Mode::ReadWrite);
     auto sd_directory = vfs->OpenDirectory(FileUtil::GetUserPath(FileUtil::UserPath::SDMCDir),
                                            FileSys::Mode::ReadWrite);
+    auto load_directory = vfs->OpenDirectory(FileUtil::GetUserPath(FileUtil::UserPath::LoadDir),
+                                             FileSys::Mode::ReadWrite);
 
     if (bis_factory == nullptr)
-        bis_factory = std::make_unique<FileSys::BISFactory>(nand_directory);
+        bis_factory = std::make_unique<FileSys::BISFactory>(nand_directory, load_directory);
     if (save_data_factory == nullptr)
         save_data_factory = std::make_unique<FileSys::SaveDataFactory>(std::move(nand_directory));
     if (sdmc_factory == nullptr)
diff --git a/src/core/hle/service/filesystem/filesystem.h b/src/core/hle/service/filesystem/filesystem.h
index aab65a2b8..7039a2247 100644
--- a/src/core/hle/service/filesystem/filesystem.h
+++ b/src/core/hle/service/filesystem/filesystem.h
@@ -52,6 +52,8 @@ std::shared_ptr<FileSys::RegisteredCache> GetSystemNANDContents();
 std::shared_ptr<FileSys::RegisteredCache> GetUserNANDContents();
 std::shared_ptr<FileSys::RegisteredCache> GetSDMCContents();
 
+FileSys::VirtualDir GetModificationLoadRoot(u64 title_id);
+
 // Creates the SaveData, SDMC, and BIS Factories. Should be called once and before any function
 // above is called.
 void CreateFactories(const FileSys::VirtualFilesystem& vfs, bool overwrite = true);
diff --git a/src/video_core/engines/maxwell_3d.h b/src/video_core/engines/maxwell_3d.h
index b81b0723d..16cdfc7e2 100644
--- a/src/video_core/engines/maxwell_3d.h
+++ b/src/video_core/engines/maxwell_3d.h
@@ -461,7 +461,11 @@ public:
                     u32 entry;
                 } macros;
 
-                INSERT_PADDING_WORDS(0x1B8);
+                INSERT_PADDING_WORDS(0x189);
+
+                u32 tfb_enabled;
+
+                INSERT_PADDING_WORDS(0x2E);
 
                 RenderTargetConfig rt[NumRenderTargets];
 
@@ -594,7 +598,9 @@ public:
 
                 u32 depth_write_enabled;
 
-                INSERT_PADDING_WORDS(0x7);
+                u32 alpha_test_enabled;
+
+                INSERT_PADDING_WORDS(0x6);
 
                 u32 d3d_cull_mode;
 
@@ -977,6 +983,7 @@ private:
                   "Field " #field_name " has invalid position")
 
 ASSERT_REG_POSITION(macros, 0x45);
+ASSERT_REG_POSITION(tfb_enabled, 0x1D1);
 ASSERT_REG_POSITION(rt, 0x200);
 ASSERT_REG_POSITION(viewport_transform[0], 0x280);
 ASSERT_REG_POSITION(viewport, 0x300);
@@ -996,6 +1003,7 @@ ASSERT_REG_POSITION(zeta_height, 0x48b);
 ASSERT_REG_POSITION(depth_test_enable, 0x4B3);
 ASSERT_REG_POSITION(independent_blend_enable, 0x4B9);
 ASSERT_REG_POSITION(depth_write_enabled, 0x4BA);
+ASSERT_REG_POSITION(alpha_test_enabled, 0x4BB);
 ASSERT_REG_POSITION(d3d_cull_mode, 0x4C2);
 ASSERT_REG_POSITION(depth_test_func, 0x4C3);
 ASSERT_REG_POSITION(blend, 0x4CF);
diff --git a/src/video_core/engines/maxwell_compute.cpp b/src/video_core/engines/maxwell_compute.cpp
index e4e5f9e5e..59e28b22d 100644
--- a/src/video_core/engines/maxwell_compute.cpp
+++ b/src/video_core/engines/maxwell_compute.cpp
@@ -2,12 +2,29 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include "common/logging/log.h"
+#include "core/core.h"
 #include "video_core/engines/maxwell_compute.h"
 
 namespace Tegra {
 namespace Engines {
 
-void MaxwellCompute::WriteReg(u32 method, u32 value) {}
+void MaxwellCompute::WriteReg(u32 method, u32 value) {
+    ASSERT_MSG(method < Regs::NUM_REGS,
+               "Invalid MaxwellCompute register, increase the size of the Regs structure");
+
+    regs.reg_array[method] = value;
+
+    switch (method) {
+    case MAXWELL_COMPUTE_REG_INDEX(compute): {
+        LOG_CRITICAL(HW_GPU, "Compute shaders are not implemented");
+        UNREACHABLE();
+        break;
+    }
+    default:
+        break;
+    }
+}
 
 } // namespace Engines
 } // namespace Tegra
diff --git a/src/video_core/engines/maxwell_compute.h b/src/video_core/engines/maxwell_compute.h
index 2b3e4ced6..6ea934fb9 100644
--- a/src/video_core/engines/maxwell_compute.h
+++ b/src/video_core/engines/maxwell_compute.h
@@ -4,17 +4,53 @@
 
 #pragma once
 
+#include <array>
+#include "common/assert.h"
+#include "common/bit_field.h"
+#include "common/common_funcs.h"
 #include "common/common_types.h"
 
 namespace Tegra::Engines {
 
+#define MAXWELL_COMPUTE_REG_INDEX(field_name)                                                      \
+    (offsetof(Tegra::Engines::MaxwellCompute::Regs, field_name) / sizeof(u32))
+
 class MaxwellCompute final {
 public:
     MaxwellCompute() = default;
     ~MaxwellCompute() = default;
 
+    struct Regs {
+        static constexpr std::size_t NUM_REGS = 0xCF8;
+
+        union {
+            struct {
+                INSERT_PADDING_WORDS(0x281);
+
+                union {
+                    u32 compute_end;
+                    BitField<0, 1, u32> unknown;
+                } compute;
+
+                INSERT_PADDING_WORDS(0xA76);
+            };
+            std::array<u32, NUM_REGS> reg_array;
+        };
+    } regs{};
+
+    static_assert(sizeof(Regs) == Regs::NUM_REGS * sizeof(u32),
+                  "MaxwellCompute Regs has wrong size");
+
     /// Write the value to the register identified by method.
     void WriteReg(u32 method, u32 value);
 };
 
+#define ASSERT_REG_POSITION(field_name, position)                                                  \
+    static_assert(offsetof(MaxwellCompute::Regs, field_name) == position * 4,                      \
+                  "Field " #field_name " has invalid position")
+
+ASSERT_REG_POSITION(compute, 0x281);
+
+#undef ASSERT_REG_POSITION
+
 } // namespace Tegra::Engines
diff --git a/src/video_core/renderer_opengl/gl_rasterizer.cpp b/src/video_core/renderer_opengl/gl_rasterizer.cpp
index 70fb54507..44850d193 100644
--- a/src/video_core/renderer_opengl/gl_rasterizer.cpp
+++ b/src/video_core/renderer_opengl/gl_rasterizer.cpp
@@ -450,6 +450,8 @@ void RasterizerOpenGL::DrawArrays() {
     SyncBlendState();
     SyncLogicOpState();
     SyncCullMode();
+    SyncAlphaTest();
+    SyncTransformFeedback();
 
     // TODO(bunnei): Sync framebuffer_scale uniform here
     // TODO(bunnei): Sync scissorbox uniform(s) here
@@ -883,4 +885,24 @@ void RasterizerOpenGL::SyncLogicOpState() {
     state.logic_op.operation = MaxwellToGL::LogicOp(regs.logic_op.operation);
 }
 
+void RasterizerOpenGL::SyncAlphaTest() {
+    const auto& regs = Core::System::GetInstance().GPU().Maxwell3D().regs;
+
+    // TODO(Rodrigo): Alpha testing is a legacy OpenGL feature, but it can be
+    // implemented with a test+discard in fragment shaders.
+    if (regs.alpha_test_enabled != 0) {
+        LOG_CRITICAL(Render_OpenGL, "Alpha testing is not implemented");
+        UNREACHABLE();
+    }
+}
+
+void RasterizerOpenGL::SyncTransformFeedback() {
+    const auto& regs = Core::System::GetInstance().GPU().Maxwell3D().regs;
+
+    if (regs.tfb_enabled != 0) {
+        LOG_CRITICAL(Render_OpenGL, "Transform feedbacks are not implemented");
+        UNREACHABLE();
+    }
+}
+
 } // namespace OpenGL
diff --git a/src/video_core/renderer_opengl/gl_rasterizer.h b/src/video_core/renderer_opengl/gl_rasterizer.h
index bf9560bdc..c3f1e14bf 100644
--- a/src/video_core/renderer_opengl/gl_rasterizer.h
+++ b/src/video_core/renderer_opengl/gl_rasterizer.h
@@ -158,6 +158,12 @@ private:
     /// Syncs the LogicOp state to match the guest state
     void SyncLogicOpState();
 
+    /// Syncs the alpha test state to match the guest state
+    void SyncAlphaTest();
+
+    /// Syncs the transform feedback state to match the guest state
+    void SyncTransformFeedback();
+
     bool has_ARB_direct_state_access = false;
     bool has_ARB_multi_bind = false;
     bool has_ARB_separate_shader_objects = false;
diff --git a/src/yuzu/game_list.cpp b/src/yuzu/game_list.cpp
index e8b2f720a..991ae10cd 100644
--- a/src/yuzu/game_list.cpp
+++ b/src/yuzu/game_list.cpp
@@ -318,9 +318,14 @@ void GameList::PopupContextMenu(const QPoint& menu_location) {
     int row = item_model->itemFromIndex(item)->row();
     QStandardItem* child_file = item_model->invisibleRootItem()->child(row, COLUMN_NAME);
     u64 program_id = child_file->data(GameListItemPath::ProgramIdRole).toULongLong();
+    std::string path = child_file->data(GameListItemPath::FullPathRole).toString().toStdString();
 
     QMenu context_menu;
     QAction* open_save_location = context_menu.addAction(tr("Open Save Data Location"));
+    QAction* open_lfs_location = context_menu.addAction(tr("Open Mod Data Location"));
+    context_menu.addSeparator();
+    QAction* dump_romfs = context_menu.addAction(tr("Dump RomFS"));
+    QAction* copy_tid = context_menu.addAction(tr("Copy Title ID to Clipboard"));
     QAction* navigate_to_gamedb_entry = context_menu.addAction(tr("Navigate to GameDB entry"));
 
     open_save_location->setEnabled(program_id != 0);
@@ -329,6 +334,10 @@ void GameList::PopupContextMenu(const QPoint& menu_location) {
 
     connect(open_save_location, &QAction::triggered,
             [&]() { emit OpenFolderRequested(program_id, GameListOpenTarget::SaveData); });
+    connect(open_lfs_location, &QAction::triggered,
+            [&]() { emit OpenFolderRequested(program_id, GameListOpenTarget::ModData); });
+    connect(dump_romfs, &QAction::triggered, [&]() { emit DumpRomFSRequested(program_id, path); });
+    connect(copy_tid, &QAction::triggered, [&]() { emit CopyTIDRequested(program_id); });
     connect(navigate_to_gamedb_entry, &QAction::triggered,
             [&]() { emit NavigateToGamedbEntryRequested(program_id, compatibility_list); });
 
diff --git a/src/yuzu/game_list.h b/src/yuzu/game_list.h
index 2713e7b54..3bf51870e 100644
--- a/src/yuzu/game_list.h
+++ b/src/yuzu/game_list.h
@@ -28,7 +28,10 @@ namespace FileSys {
 class VfsFilesystem;
 }
 
-enum class GameListOpenTarget { SaveData };
+enum class GameListOpenTarget {
+    SaveData,
+    ModData,
+};
 
 class GameList : public QWidget {
     Q_OBJECT
@@ -89,6 +92,8 @@ signals:
     void GameChosen(QString game_path);
     void ShouldCancelWorker();
     void OpenFolderRequested(u64 program_id, GameListOpenTarget target);
+    void DumpRomFSRequested(u64 program_id, const std::string& game_path);
+    void CopyTIDRequested(u64 program_id);
     void NavigateToGamedbEntryRequested(u64 program_id,
                                         const CompatibilityList& compatibility_list);
 
diff --git a/src/yuzu/main.cpp b/src/yuzu/main.cpp
index 45bb1d1d1..d74489935 100644
--- a/src/yuzu/main.cpp
+++ b/src/yuzu/main.cpp
@@ -7,6 +7,22 @@
 #include <memory>
 #include <thread>
 
+// VFS includes must be before glad as they will conflict with Windows file api, which uses defines.
+#include "core/file_sys/vfs.h"
+#include "core/file_sys/vfs_real.h"
+
+// These are wrappers to avoid the calls to CreateDirectory and CreateFile becuase of the Windows
+// defines.
+static FileSys::VirtualDir VfsFilesystemCreateDirectoryWrapper(
+    const FileSys::VirtualFilesystem& vfs, const std::string& path, FileSys::Mode mode) {
+    return vfs->CreateDirectory(path, mode);
+}
+
+static FileSys::VirtualFile VfsDirectoryCreateFileWrapper(const FileSys::VirtualDir& dir,
+                                                          const std::string& path) {
+    return dir->CreateFile(path);
+}
+
 #include <fmt/ostream.h>
 #include <glad/glad.h>
 
@@ -30,16 +46,18 @@
 #include "common/telemetry.h"
 #include "core/core.h"
 #include "core/crypto/key_manager.h"
+#include "core/file_sys/bis_factory.h"
 #include "core/file_sys/card_image.h"
 #include "core/file_sys/content_archive.h"
 #include "core/file_sys/control_metadata.h"
 #include "core/file_sys/patch_manager.h"
 #include "core/file_sys/registered_cache.h"
+#include "core/file_sys/romfs.h"
 #include "core/file_sys/savedata_factory.h"
 #include "core/file_sys/submission_package.h"
-#include "core/file_sys/vfs_real.h"
 #include "core/hle/kernel/process.h"
 #include "core/hle/service/filesystem/filesystem.h"
+#include "core/hle/service/filesystem/fsp_ldr.h"
 #include "core/loader/loader.h"
 #include "core/perf_stats.h"
 #include "core/settings.h"
@@ -362,6 +380,8 @@ void GMainWindow::RestoreUIState() {
 void GMainWindow::ConnectWidgetEvents() {
     connect(game_list, &GameList::GameChosen, this, &GMainWindow::OnGameListLoadFile);
     connect(game_list, &GameList::OpenFolderRequested, this, &GMainWindow::OnGameListOpenFolder);
+    connect(game_list, &GameList::DumpRomFSRequested, this, &GMainWindow::OnGameListDumpRomFS);
+    connect(game_list, &GameList::CopyTIDRequested, this, &GMainWindow::OnGameListCopyTID);
     connect(game_list, &GameList::NavigateToGamedbEntryRequested, this,
             &GMainWindow::OnGameListNavigateToGamedbEntry);
 
@@ -713,6 +733,12 @@ void GMainWindow::OnGameListOpenFolder(u64 program_id, GameListOpenTarget target
                                                                 program_id, user_id, 0);
         break;
     }
+    case GameListOpenTarget::ModData: {
+        open_target = "Mod Data";
+        const auto load_dir = FileUtil::GetUserPath(FileUtil::UserPath::LoadDir);
+        path = fmt::format("{}{:016X}", load_dir, program_id);
+        break;
+    }
     default:
         UNIMPLEMENTED();
     }
@@ -730,6 +756,120 @@ void GMainWindow::OnGameListOpenFolder(u64 program_id, GameListOpenTarget target
     QDesktopServices::openUrl(QUrl::fromLocalFile(qpath));
 }
 
+static std::size_t CalculateRomFSEntrySize(const FileSys::VirtualDir& dir, bool full) {
+    std::size_t out = 0;
+
+    for (const auto& subdir : dir->GetSubdirectories()) {
+        out += 1 + CalculateRomFSEntrySize(subdir, full);
+    }
+
+    return out + (full ? dir->GetFiles().size() : 0);
+}
+
+static bool RomFSRawCopy(QProgressDialog& dialog, const FileSys::VirtualDir& src,
+                         const FileSys::VirtualDir& dest, std::size_t block_size, bool full) {
+    if (src == nullptr || dest == nullptr || !src->IsReadable() || !dest->IsWritable())
+        return false;
+    if (dialog.wasCanceled())
+        return false;
+
+    if (full) {
+        for (const auto& file : src->GetFiles()) {
+            const auto out = VfsDirectoryCreateFileWrapper(dest, file->GetName());
+            if (!FileSys::VfsRawCopy(file, out, block_size))
+                return false;
+            dialog.setValue(dialog.value() + 1);
+            if (dialog.wasCanceled())
+                return false;
+        }
+    }
+
+    for (const auto& dir : src->GetSubdirectories()) {
+        const auto out = dest->CreateSubdirectory(dir->GetName());
+        if (!RomFSRawCopy(dialog, dir, out, block_size, full))
+            return false;
+        dialog.setValue(dialog.value() + 1);
+        if (dialog.wasCanceled())
+            return false;
+    }
+
+    return true;
+}
+
+void GMainWindow::OnGameListDumpRomFS(u64 program_id, const std::string& game_path) {
+    const auto path = fmt::format("{}{:016X}/romfs",
+                                  FileUtil::GetUserPath(FileUtil::UserPath::DumpDir), program_id);
+
+    const auto failed = [this, &path] {
+        QMessageBox::warning(this, tr("RomFS Extraction Failed!"),
+                             tr("There was an error copying the RomFS files or the user "
+                                "cancelled the operation."));
+        vfs->DeleteDirectory(path);
+    };
+
+    const auto loader = Loader::GetLoader(vfs->OpenFile(game_path, FileSys::Mode::Read));
+    if (loader == nullptr) {
+        failed();
+        return;
+    }
+
+    FileSys::VirtualFile file;
+    if (loader->ReadRomFS(file) != Loader::ResultStatus::Success) {
+        failed();
+        return;
+    }
+
+    const auto romfs =
+        loader->IsRomFSUpdatable()
+            ? FileSys::PatchManager(program_id).PatchRomFS(file, loader->ReadRomFSIVFCOffset())
+            : file;
+
+    const auto extracted = FileSys::ExtractRomFS(romfs, FileSys::RomFSExtractionType::Full);
+    if (extracted == nullptr) {
+        failed();
+        return;
+    }
+
+    const auto out = VfsFilesystemCreateDirectoryWrapper(vfs, path, FileSys::Mode::ReadWrite);
+
+    if (out == nullptr) {
+        failed();
+        return;
+    }
+
+    bool ok;
+    const auto res = QInputDialog::getItem(
+        this, tr("Select RomFS Dump Mode"),
+        tr("Please select the how you would like the RomFS dumped.<br>Full will copy all of the "
+           "files into the new directory while <br>skeleton will only create the directory "
+           "structure."),
+        {"Full", "Skeleton"}, 0, false, &ok);
+    if (!ok)
+        failed();
+
+    const auto full = res == "Full";
+    const auto entry_size = CalculateRomFSEntrySize(extracted, full);
+
+    QProgressDialog progress(tr("Extracting RomFS..."), tr("Cancel"), 0, entry_size, this);
+    progress.setWindowModality(Qt::WindowModal);
+    progress.setMinimumDuration(100);
+
+    if (RomFSRawCopy(progress, extracted, out, 0x400000, full)) {
+        progress.close();
+        QMessageBox::information(this, tr("RomFS Extraction Succeeded!"),
+                                 tr("The operation completed successfully."));
+        QDesktopServices::openUrl(QUrl::fromLocalFile(QString::fromStdString(path)));
+    } else {
+        progress.close();
+        failed();
+    }
+}
+
+void GMainWindow::OnGameListCopyTID(u64 program_id) {
+    QClipboard* clipboard = QGuiApplication::clipboard();
+    clipboard->setText(QString::fromStdString(fmt::format("{:016X}", program_id)));
+}
+
 void GMainWindow::OnGameListNavigateToGamedbEntry(u64 program_id,
                                                   const CompatibilityList& compatibility_list) {
     const auto it = FindMatchingCompatibilityEntry(compatibility_list, program_id);
@@ -790,7 +930,8 @@ void GMainWindow::OnMenuInstallToNAND() {
         return;
     }
 
-    const auto qt_raw_copy = [this](FileSys::VirtualFile src, FileSys::VirtualFile dest) {
+    const auto qt_raw_copy = [this](const FileSys::VirtualFile& src,
+                                    const FileSys::VirtualFile& dest, std::size_t block_size) {
         if (src == nullptr || dest == nullptr)
             return false;
         if (!dest->Resize(src->GetSize()))
diff --git a/src/yuzu/main.h b/src/yuzu/main.h
index 552e3e61c..8ee9242b1 100644
--- a/src/yuzu/main.h
+++ b/src/yuzu/main.h
@@ -138,6 +138,8 @@ private slots:
     /// Called whenever a user selects a game in the game list widget.
     void OnGameListLoadFile(QString game_path);
     void OnGameListOpenFolder(u64 program_id, GameListOpenTarget target);
+    void OnGameListDumpRomFS(u64 program_id, const std::string& game_path);
+    void OnGameListCopyTID(u64 program_id);
     void OnGameListNavigateToGamedbEntry(u64 program_id,
                                          const CompatibilityList& compatibility_list);
     void OnMenuLoadFile();