rust for cortex-m7 baremetal

Update 14 December 2018: After the release of stable 1.31.0 (aka 2018 Edition), it is no longer necessary to switch to the nightly channel to get access to thumb7em-none-eabi / Cortex-M4 and Cortex-M7 components. Updated examples and commands accordingly.
For more details on embedded development using Rust, the official Rust embedded docs site is the place to go, in particular, you can start with The embedded Rust book.
 
 
This is a reminder for myself, if you want to install Rust for a baremetal Cortex-M7 target, this seems to be a tier 3 platform:

https://forge.rust-lang.org/platform-support.html

Higlighting the relevant part:

Target	std	rustc	cargo	notes
...
msp430-none-elf	*			16-bit MSP430 microcontrollers
sparc64-unknown-netbsd	✓	✓		NetBSD/sparc64
thumbv6m-none-eabi	*			Bare Cortex-M0, M0+, M1
thumbv7em-none-eabi	*			Bare Cortex-M4, M7
thumbv7em-none-eabihf	*			Bare Cortex-M4F, M7F, FPU, hardfloat
thumbv7m-none-eabi	*			Bare Cortex-M3
...
x86_64-unknown-openbsd	✓	✓		64-bit OpenBSD

In order to enable the relevant support, use the nightly build and use stable >= 1.31.0 and add the relevant target:

eddy@feodora:~/usr/src/rust-uc$ rustup show
Default host: x86_64-unknown-linux-gnu

installed toolchains
--------------------

stable-x86_64-unknown-linux-gnu
nightly-x86_64-unknown-linux-gnu (default)

active toolchain
----------------

nightly-x86_64-unknown-linux-gnu (default)
rustc 1.28.0-nightly (cb20f68d0 2018-05-21)

eddy@feodora:~/usr/src/rust$ rustup show
Default host: x86_64-unknown-linux-gnu

stable-x86_64-unknown-linux-gnu (default)
rustc 1.31.0 (abe02cefd 2018-12-04)

If not using nightly, switch to that:

eddy@feodora:~/usr/src/rust-uc$ rustup default nightly-x86_64-unknown-linux-gnu
info: using existing install for 'nightly-x86_64-unknown-linux-gnu'
info: default toolchain set to 'nightly-x86_64-unknown-linux-gnu'

  nightly-x86_64-unknown-linux-gnu unchanged - rustc 1.28.0-nightly (cb20f68d0 2018-05-21)

Add the needed target:

eddy@feodora:~/usr/src/rust$ rustup target add thumbv7em-none-eabi
info: downloading component 'rust-std' for 'thumbv7em-none-eabi'
info: installing component 'rust-std' for 'thumbv7em-none-eabi'
eddy@feodora:~/usr/src/rust$ rustup show
Default host: x86_64-unknown-linux-gnu

installed targets for active toolchain
--------------------------------------

thumbv7em-none-eabi
x86_64-unknown-linux-gnu

active toolchain
----------------

stable-x86_64-unknown-linux-gnu (default)
rustc 1.31.0 (abe02cefd 2018-12-04)

Then compile with --target.