set default runner to arm-none-eabi-gdb

with this `xargo run` will build the program *and* immediately start a GDB
session.

.cargo/config

@@ -1,4 +1,5 @@
 [target.thumbv6m-none-eabi]
+runner = 'arm-none-eabi-gdb'
 rustflags = [
   "-C", "link-arg=-Tlink.x",
   "-C", "linker=arm-none-eabi-ld",
@@ -6,6 +7,7 @@ rustflags = [
 ]
 
 [target.thumbv7m-none-eabi]
+runner = 'arm-none-eabi-gdb'
 rustflags = [
   "-C", "link-arg=-Tlink.x",
   "-C", "linker=arm-none-eabi-ld",
@@ -13,6 +15,7 @@ rustflags = [
 ]
 
 [target.thumbv7em-none-eabi]
+runner = 'arm-none-eabi-gdb'
 rustflags = [
   "-C", "link-arg=-Tlink.x",
   "-C", "linker=arm-none-eabi-ld",
@@ -20,6 +23,7 @@ rustflags = [
 ]
 
 [target.thumbv7em-none-eabihf]
+runner = 'arm-none-eabi-gdb'
 rustflags = [
   "-C", "link-arg=-Tlink.x",
   "-C", "linker=arm-none-eabi-ld",

Cargo.toml

@@ -6,7 +6,7 @@ keywords = ["arm", "cortex-m", "template"]
 license = "MIT OR Apache-2.0"
 name = "cortex-m-quickstart"
 repository = "https://github.com/japaric/cortex-m-quickstart"
-version = "0.1.5"
+version = "0.1.6"
 
 [dependencies]
 cortex-m = "0.2.6"

src/lib.rs

@@ -121,6 +121,16 @@
 //! $ arm-none-eabi-gdb target/..
 //! ```
 //!
+//! **NOTE** As of nightly-2017-05-14 or so and cortex-m-quickstart v0.1.6 you
+//! can simply run `cargo run` or `cargo run --example $ex` to build and flash
+//! the program, and immediately start a debug session. IOW, it lets you omit
+//! `arm-none-eabi-gdb` command.
+//!
+//! ```
+//! $ cargo run --example hello
+//! > # drop you into GDB session
+//! ```
+//!
 //! # Examples
 //!
 //! Check the [examples module](./examples/index.html)