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Migration Guide: Moving from master to main Branch (Post-Oct 2024)

Since the main branch (after October 2024) introduces breaking changes to the build environment, if users of the legacy master branch want to keep upstream or use a new version of the Rust toolchain, they will need to migrate their TA to the new environment.

Note that the migration is mainly for building scripts to support both no-std and std building for TA, no need for modifying your application code.

Current Structure

We have retained almost the same structure as the original but removed ta_arm.lds and ta_aarch64.lds from the directory structure. Besides we have some modification on ta/ta_static.rs, ta/build.rs and all Makefiles. (See the explanation in next part).

For example the current examples/acipher-rs/:

examples/acipher-rs/
├── host
│   ├── Cargo.toml
│   ├── Makefile
│   └── src
│       └── main.rs
├── Makefile
├── proto
│   ├── build.rs
│   ├── Cargo.toml
│   └── src
│       └── lib.rs
├── ta
│   ├── build.rs
│   ├── Cargo.toml
│   ├── Makefile
│   ├── src
│   │   └── main.rs
│   ├── ta_static.rs
│   └── Xargo.toml
└── uuid.txt

Changes in Build Scripts

  1. TA linking script: ta_arm.lds and ta_aarch64.lds.
    These linking scripts define the low-level TA ELF sections arrangement (e.g., .text section in ELF). They have been removed, and we now use the lds file from OP-TEE's TA dev-kit, for example, located in optee_os/out/arm-plat-vexpress/export-ta_arm64/src/ta.ld.S. This change helps to stay upstream with OP-TEE OS and makes it more stable when running on OP-TEE OS.

  2. ta_static.rs: C FFI primitives, such as ta_heap_size and ta_props.
    This file helps to set TA properties in a C-like manner in the TA ELF for OP-TEE OS to load.
    The change involves modifying imports of primitives, e.g., from libc::c_int to core::c_int, and from std::u64::MAX to core::primitive::u64::MAX. This helps ensure support for both no_std and std-based environments.

  3. build.rs:
    Since TA is not a normal ELF, it has a header before the ELF sections.
    This file is the main entry point for building a TA as ELF and adding the specific header. It uses configurations such as ta_static.rs, user_ta_header.rs, and the linking script ta.ld.S. It also defines the linking with OP-TEE's C libraries (libutee and libutils) from OP-TEE's TA dev-kit.

    The changes are:

    a. Move linking parameters from the original /.cargo/config: This change is primarily designed to accommodate more complex build targets. For standard TAs, the specific build targets are aarch64-unknown-optee-trustzone and arm-unknown-optee-trustzone. For example, in the no-std mode for aarch64, both no-std TAs and CAs are built with the aarch64-unknown-linux-gnu target. However, in std mode, TAs are built with the aarch64-unknown-optee-trustzone target, while CAs remain built with the aarch64-unknown-linux-gnu target. This change allows us to decouple TA's linking parameters from the target, as they are now defined within TA's build.rs.

    b. Add cargo:rustc-link-arg=--no-warn-mismatch to work around the EABI version mismatch linking error: symbols.o with EABI version 0 and other objects are EABI version 5.

  4. ENV variables:
    The original script for setting the toolchain path has some modifications. Due to the more complex building options mentioned above, CROSS_COMPILE_{HOST, TA} and TARGET_{HOST, TA} should be set by source environment. You should also set whether you want to build in STD mode (export STD=y) and specify the target architecture (ARM32 or AArch64) for both CA and TA. Running source environment will set up all toolchains and libraries.

  5. Makefile Polishing:
    a. Top-level Makefile (examples/*/Makefile): Reads the CROSS_COMPILE_{HOST, TA} and TARGET_{HOST, TA}.
    b. host/Makefile: Simplified and polished for the changes in ENV variables.
    c. ta/Makefile: For std TAs, checks if the STD environment variable is set, and further simplifications and polish are done.

Step 1: Migrating Projects

Case 1: Default Migration (No Custom Modifications to Build Scripts)

If you have developed based on one of our example structures and haven't modified the build scripts mentioned above, you can simply copy a current example and move your code into it.
Note that the Makefile for std TAs has tiny differences from the no_std one. If you are using a no_std TA, refer to hello_world-rs. For std TAs, refer to serde-rs.

We provide a shell script to assist with this migration (you may need to make small adjustments based on whether you are building in no_std or std mode). Here is an example for no_std:

TARGET_EXAMPLE="your_project"
OLD_ROOT_PATH="/path/to/old/sdk"
NEW_PATH="/path/to/current/sdk"

# Duplicate the hello-world example in the new path as a template
cp -r ${NEW_PATH}/examples/hello_world-rs ${NEW_PATH}/examples/${TARGET_EXAMPLE}

# Remove the source code directory and copy from the old path to the new path
# including: src/ and Cargo.toml in host, ta, proto
(cd ${NEW_PATH}/examples/${TARGET_EXAMPLE}/host && rm -rf src/ Cargo.* && \
cp -r ${OLD_ROOT_PATH}/examples/${TARGET_EXAMPLE}/host/src . && \
cp ${OLD_ROOT_PATH}/examples/${TARGET_EXAMPLE}/host/Cargo.toml .)
(cd ${NEW_PATH}/examples/${TARGET_EXAMPLE}/ta && rm -rf src/ Cargo.* && \
cp -r ${OLD_ROOT_PATH}/examples/${TARGET_EXAMPLE}/ta/src . && \
cp ${OLD_ROOT_PATH}/examples/${TARGET_EXAMPLE}/ta/Cargo.toml .)
(cd ${NEW_PATH}/examples/${TARGET_EXAMPLE}/proto && rm -rf src/ Cargo.* && \
cp -r ${OLD_ROOT_PATH}/examples/${TARGET_EXAMPLE}/proto/src . && \
cp ${OLD_ROOT_PATH}/examples/${TARGET_EXAMPLE}/proto/Cargo.toml .)

# Copy the UUID file from the old path to the new path
cp ${OLD_ROOT_PATH}/examples/${TARGET_EXAMPLE}/uuid.txt \
${NEW_PATH}/examples/${TARGET_EXAMPLE}/uuid.txt

# Update binary names in host/Cargo.toml and host/Makefile
sed -i "s/hello_world-rs/${TARGET_EXAMPLE}/g" \
${NEW_PATH}/examples/${TARGET_EXAMPLE}/host/Cargo.toml
sed -i "s/hello_world-rs/${TARGET_EXAMPLE}/g" \
${NEW_PATH}/examples/${TARGET_EXAMPLE}/host/Makefile

Case 2: Custom Migration (With Modified Build Scripts)

If you have made changes to your build scripts, follow the steps below to manually migrate those files:

  1. TA linking script ta_arm.lds and ta_aarch64.lds:
    Usually, developers don't need to modify those files. If you have made any changes, compare the diff between your file and optee_os/out/arm-plat-vexpress/export-ta_{arm64, arm32}/src/ta.ld.S in the current SDK. This ta.ld.S file is currently not included in SDK but in OPTEE_OS repo.

  2. ta_static.rs:
    Usually, developers don't need to modify this file. If you have made modifications to this file, compare them with the latest version here:
    ta_static.rs diff

  3. build.rs:
    Usually, developers don't need to modify this file. If you have made changes to link other libraries or dependencies in build.rs, compare the two versions and migrate accordingly:
    build.rs diff

  4. Makefiles:
    You may have modified some of the Makefiles. Please compare them with the current versions to ensure compatibility:

Step 2: Update Cargo.toml

You may need to update your Cargo.toml file to include newer versions of crates that depend on the new Rust toolchain. Refer to the rust-toolchain.toml file to verify the current toolchain. If you update any crates, be prepared for potential code changes to accommodate new interfaces.

Step 3: Build and Resolve Errors

After updating the necessary files, rebuild the project. During the process, errors might arise due to crate version mismatches or other updates. Make sure to resolve these errors by adjusting your code accordingly.