Hymo is an experimental hybrid mount meta-module designed for KernelSU. It refactors core logic with native C++ and introduces HymoFS, which attempts to hijack the kernel file system to use VFS mapping. Note that this approach is intrusive and may cause system instability.

🇨🇳 中文

Hymo is a native daemon designed to handle complex mounting scenarios, though it may introduce new compatibility issues.

• Native Implementation: Core logic is written in C++ to avoid Shell script dependencies, though this introduces binary compatibility risks.
• Direct System Calls: Uses Linux Mount APIs like fsopen, fsconfig, fsmount, move_mount directly. This bypasses standard mount safeguards and may lead to undefined behavior if misused.
• Startup Impact: While optimized, the module loading process inevitably adds overhead to the system boot time and may delay startup.

Hymo introduces experimental HymoFS technology, building a complex mount strategy:

• HymoFS (Kernel Mode): Requires patching the kernel source to open a kernel interface. It hijacks the underlying file system to implement file mapping. This is a significant kernel modification and may compromise system integrity or cause data loss.
• OverlayFS (General Mode): The standard solution, utilizing kernel OverlayFS features for file-level merging.
• Magic Mount (Compatibility Mode): A traditional Bind Mount fallback for old kernels or special partitions.
• Dynamic Decision: The daemon attempts to detect the environment to select a mode, or users can force a specific mode via WebUI.

• Incremental Update: Attempts to compare module module.prop and file timestamps at startup.
• I/O Operations: Synchronizes changed module files to the working directory. While intended to reduce I/O, the checking process itself consumes resources and may wear flash memory over time.

• Space Management: Detects kernel Tmpfs support. If supported, it uses the in-memory file system, which consumes system RAM and may lead to out-of-memory (OOM) situations on devices with limited memory.
• Tmpfs Usage: Builds module images in memory at runtime. This is volatile and data will be lost on reboot.
• Ext4 Image Fallback: Falls back to modules.img loopback image if Tmpfs is unavailable, which consumes permanent storage space.

Hymo uses a standard Makefile build system and supports cross-compilation.

Prerequisites:

• Android NDK (r25+)
• Node.js & npm (for building WebUI)
• Make & Zip

HymoFS Patch

HymoFS provides a smart setup.sh script for easy integration into your kernel source.

curl -LSs https://raw.githubusercontent.com/Anatdx/HymoFS/main/setup.sh | bash -s defconfig arch/arm64/configs/gki_defconfig

• Branch Selection: Attempts to detect your kernel version (6.1 or 6.6) and switch branches. This detection may fail on non-standard kernels.
• KernelSU Detection: Tries to detect KernelSU.
• SUSFS Integration: Attempts to apply compatibility patches if SUSFS is detected. This integration is fragile and may break with updates to either project.

Build Commands:

# Compile all architectures and package
make zip

# Compile arm64 only and generate test package
make testzip

Install: The generated zip package can be flashed in KernelSU Manager, assuming the manager supports the format.

Hymo includes a command-line tool hymod for debugging the daemon and HymoFS rules.

hymod [OPTIONS] [COMMAND]

• mount: Attempt to mount all modules (Default action).
• modules: List modules that Hymo believes are active.
• storage: Show current storage status.
• reload: Attempt to reload HymoFS mappings.
• clear: Clear all HymoFS mappings (Use this if the system becomes unstable).
• list: List active HymoFS kernel rules.
• version: Show protocol version.
• gen-config: Generate a default configuration file.
• show-config: Display the current configuration.
• add <mod_id>: Manually add a module's rules.
• delete <mod_id>: Manually remove a module's rules.
• set-mirror <path>: Set custom mirror path.
• raw <cmd> ...: Execute raw HymoFS low-level commands. Warning: Improper use will crash the system.

• -c, --config FILE: Specify a custom config file path.
• -m, --moduledir DIR: Specify the module directory.
• -v, --verbose: Enable verbose logging.
• -p, --partition NAME: Add a partition to scan.

• KernelSU: Root solution.
• Libcxx: Android NDK C++ standard library.
• Contributors: Thanks for testing.

Disclaimer: This project involves dangerous low-level system modifications. Data loss is likely. Please ensure data backup before use. The developer is not responsible for any damage, bricked devices, or nuclear war caused by using this module.