change layout of books

1 files changed, 77 insertions, 0 deletions

diff --git a/book/en/src/by-example/tips.md b/book/en/src/by-example/tips.md
new file mode 100644
index 0000000..8f71599
--- /dev/null
+++ b/book/en/src/by-example/tips.md
@@ -0,0 +1,77 @@
+# Tips & tricks
+
+## Generics
+
+Resources shared between two or more tasks implement the `Mutex` trait in *all*
+contexts, even on those where a critical section is not required to access the
+data. This lets you easily write generic code that operates on resources and can
+be called from different tasks. Here's one such example:
+
+``` rust
+{{#include ../../../../examples/generics.rs}}
+```
+
+``` console
+$ cargo run --example generics
+{{#include ../../../../ci/expected/generics.run}}```
+
+This also lets you change the static priorities of tasks without having to
+rewrite code. If you consistently use `lock`s to access the data behind shared
+resources then your code will continue to compile when you change the priority
+of tasks.
+
+## Conditional compilation
+
+You can use conditional compilation (`#[cfg]`) on resources (`static [mut]`
+items) and tasks (`fn` items). The effect of using `#[cfg]` attributes is that
+the resource / task will *not* be injected into the prelude of tasks that use
+them (see `resources`, `spawn` and `schedule`) if the condition doesn't hold.
+
+The example below logs a message whenever the `foo` task is spawned, but only if
+the program has been compiled using the `dev` profile.
+
+``` rust
+{{#include ../../../../examples/cfg.rs}}
+```
+
+## Running tasks from RAM
+
+The main goal of moving the specification of RTFM applications to attributes in
+RTFM v0.4.x was to allow inter-operation with other attributes. For example, the
+`link_section` attribute can be applied to tasks to place them in RAM; this can
+improve performance in some cases.
+
+> **IMPORTANT**: In general, the `link_section`, `export_name` and `no_mangle`
+> attributes are very powerful but also easy to misuse. Incorrectly using any of
+> these attributes can cause undefined behavior; you should always prefer to use
+> safe, higher level attributes around them like `cortex-m-rt`'s `interrupt` and
+> `exception` attributes.
+>
+> In the particular case of RAM functions there's no
+> safe abstraction for it in `cortex-m-rt` v0.6.5 but there's an [RFC] for
+> adding a `ramfunc` attribute in a future release.
+
+[RFC]: https://github.com/rust-embedded/cortex-m-rt/pull/100
+
+The example below shows how to place the higher priority task, `bar`, in RAM.
+
+``` rust
+{{#include ../../../../examples/ramfunc.rs}}
+```
+
+Running this program produces the expected output.
+
+``` console
+$ cargo run --example ramfunc
+{{#include ../../../../ci/expected/ramfunc.run}}```
+
+One can look at the output of `cargo-nm` to confirm that `bar` ended in RAM
+(`0x2000_0000`), whereas `foo` ended in Flash (`0x0000_0000`).
+
+``` console
+$ cargo nm --example ramfunc --release | grep ' foo::'
+{{#include ../../../../ci/expected/ramfunc.grep.foo}}```
+
+``` console
+$ cargo nm --example ramfunc --release | grep ' bar::'
+{{#include ../../../../ci/expected/ramfunc.grep.bar}}```