From 538cc327667c3c34cafce420ab9d74303fb2d87e Mon Sep 17 00:00:00 2001 From: Philipp Oppermann Date: Tue, 18 Apr 2017 14:58:41 +0200 Subject: [PATCH] A Xargo.toml is required as soon as we use alloc/collections --- blog/content/post/08-kernel-heap.md | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/blog/content/post/08-kernel-heap.md b/blog/content/post/08-kernel-heap.md index 3cd6d1e4..31b2c1a1 100644 --- a/blog/content/post/08-kernel-heap.md +++ b/blog/content/post/08-kernel-heap.md @@ -307,6 +307,27 @@ The `collections` crate provides the [format!] and [vec!] macros, so we use `#[m [format!]: //doc.rust-lang.org/nightly/collections/macro.format!.html [vec!]: https://doc.rust-lang.org/nightly/collections/macro.vec!.html +When we try to compile it, the following error occurs: + +``` +error[E0463]: can't find crate for `alloc` + --> src/lib.rs:16:1 + | +16 | extern crate alloc; + | ^^^^^^^^^^^^^^^^^^^ can't find crate +``` + +The problem is that [`xargo`] only cross compiles `libcore` by default. To also cross compile the `alloc` and `collections` crates, we need to create a file named `Xargo.toml` in our project root (right next to the `Cargo.toml`) with the following content: + +[`xargo`]: https://github.com/japaric/xargo + +```toml +[target.x86_64-blog_os.dependencies] +collections = {} +``` + +This instructs `xargo` that we also need `collections` and `alloc` (a dependency of `collections`). Now it should compile again. + ### Testing Now we should be able to allocate memory on the heap. Let's try it in our `rust_main`: