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## Proposed Changes
Enable multiple database backends for the slasher, either MDBX (default) or LMDB. The backend can be selected using `--slasher-backend={lmdb,mdbx}`.
## Additional Info
In order to abstract over the two library's different handling of database lifetimes I've used `Box::leak` to give the `Environment` type a `'static` lifetime. This was the only way I could think of using 100% safe code to construct a self-referential struct `SlasherDB`, where the `OpenDatabases` refers to the `Environment`. I think this is OK, as the `Environment` is expected to live for the life of the program, and both database engines leave the database in a consistent state after each write. The memory claimed for memory-mapping will be freed by the OS and appropriately flushed regardless of whether the `Environment` is actually dropped.
We are depending on two `sigp` forks of `libmdbx-rs` and `lmdb-rs`, to give us greater control over MDBX OS support and LMDB's version.
47 lines
1.7 KiB
Markdown
47 lines
1.7 KiB
Markdown
# Cross-compiling
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Lighthouse supports cross-compiling, allowing users to run a binary on one
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platform (e.g., `aarch64`) that was compiled on another platform (e.g.,
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`x86_64`).
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## Instructions
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Cross-compiling requires [`Docker`](https://docs.docker.com/engine/install/),
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[`rustembedded/cross`](https://github.com/rust-embedded/cross) and for the
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current user to be in the `docker` group.
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The binaries will be created in the `target/` directory of the Lighthouse
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project.
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### Targets
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The `Makefile` in the project contains four targets for cross-compiling:
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- `build-x86_64`: builds an optimized version for x86_64 processors (suitable for most users).
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- `build-x86_64-portable`: builds a version for x86_64 processors which avoids using some modern CPU
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instructions that are incompatible with older CPUs.
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- `build-aarch64`: builds an optimized version for 64-bit ARM processors (suitable for Raspberry Pi 4).
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- `build-aarch64-portable`: builds a version for 64-bit ARM processors which avoids using some
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modern CPU instructions. In practice, very few ARM processors lack the instructions necessary to
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run the faster non-portable build.
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For more information about optimized vs portable builds see
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[Portability](./installation-binaries.md#portability).
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### Example
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```bash
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cd lighthouse
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make build-aarch64
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```
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The `lighthouse` binary will be compiled inside a Docker container and placed
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in `lighthouse/target/aarch64-unknown-linux-gnu/release`.
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## Feature Flags
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When using the makefile the set of features used for building can be controlled with
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the environment variable `CROSS_FEATURES`. See [Feature
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Flags](./installation-source.md#feature-flags) for available features.
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