axalloc (modified for exercise)

This directory is a modified copy of axalloc 0.3.0-preview.1 from crates.io, used only by arceos-altalloc.

The parent project uses the [patch.crates-io] section in the workspace root Cargo.toml to override the published crate, ensuring that all dependent crates utilize this modified version.

Differences from upstream

• The default byte allocator is bump_allocator’s EarlyAllocator, gated by the bump_allocator Cargo feature.
• level-1 is enabled by default: the whole heap region is handed to that byte allocator (GlobalAllocator::init only calls balloc.init), instead of the stock two-level setup (bitmap page allocator + separate TLSF heap).
• The exact default feature set is bump_allocator, level-1, and axallocator/page-alloc-256m.

Optional byte-allocator features (tlsf, slab, buddy) are still present for comparison or switching back. Do not enable bump_allocator together with another byte-allocator feature: cfg_if will match only the first branch.

Role

Same as upstream: provides [GlobalAllocator] implementing [core::alloc::GlobalAlloc] for #[global_allocator]; traits and helpers come from axallocator.

License

GPL-3.0-or-later OR Apache-2.0 OR MulanPSL-2.0