# `branch-protection`
This option lets you enable branch authentication instructions on AArch64.
-This option is ignored for non-AArch64 architectures.
+This option is only accepted when targeting AArch64 architectures.
It takes some combination of the following values, separated by a `,`.
- `pac-ret` - Enable pointer authentication for non-leaf functions.
Rust's standard library does not ship with BTI or pointer authentication enabled by default.
In Cargo projects the standard library can be recompiled with pointer authentication using the nightly
-[build-std](https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#build-std) feature.
+[build-std](../../cargo/reference/unstable.html#build-std) feature.