====== ARM toolchain ======
\\
In order to compile code from an architecture (e.g x86) to another (e.g ARM), you need a cross-compiler.\\

The toolchain is already available through the ''$ARM_HOME'' environement variable which is already part of your ''$PATH'' variable.\\
Please note that all commands are ''arm-eabi-'' prefixed, exemple:\\

<code>
<user>@archix[~]: arm-eabi-gcc
This will call GDB, the GNU debugger.
</code>

[[http://eclipse.org environment|Eclipse]] is the graphical development environment we will use. It provides a convenient way to interact with the toolchain.

In the following, we'll explain the two target available for code debugging:

  * [[arm:arm#Simulator|Simulator]] | GNU GDB built-in feature,
  * [[arm:arm#JTAG-OpenOCD|JTAG]] | OpenOCD along with parallel port JTAG Wiggler.

Please note that the Cross-ARM toolchain has been built from scratch and is using statically linked libraries: this makes it possible to run on any linux system featuring the same architecture.\\
\\

===== ARM virtual machine =====
Building its own cross-compilation tool-chain is everything but a nice and funny thing to do!\\

So, to help those of you who'd like to simulate their ARM code with the ''arm-eabi-gdb'' simulator, we provides a ready-to-use fully featured VM. This VM hosts both the cross-compilation tool-chain along with latest Eclipse version and a sample code that will teaches you the way the simulator ought to be launched.\\

<WRAP leftalign round info 60%>//**__Fully featured VM with arm + eclipse__**//
We provide a VirtualBox image that contains the ARM cross-compilation tool-chain along with Eclipse [[arm:VM_Arm|here]].
</WRAP>
\\
===== Simulator =====
The ARM instruction set simulator is part of the GNU debugger ''arm-eabi-gdb''.\\
In order to use it through Eclipse, we describe below a step by step procedure:\\

<code>
#> eclipse
</code>
//Note: Eclipse will fails if you try to launch it from the server, rather use one of the archi[1..18] compute nodes.//

Now, you will create a ''New Empty C project'' and select the ''Cross GCC'' toolchain ...

{{ :arm:arm_eclipse_newproject.png?direct&600 |Creation of a new empty C project that will use a CrossGCC toolchain.}}
\\
As stated above, all binaries from our ARM toolchain feature a prefix ''arm-eabi-'' we will specify it right now along with path to the toolchain itself

{{ :arm:arm_eclipse_crossgccprefix.png?direct&500 |ARM CrossGCC prefixe and path.}}
\\
Having done the basic setup, we'll now create a new source file with the following code:

<file c test.c>
void _start(int argc, char**argv) {

	int i=10;
	int j=1;

	while (i-->=0) {
		j*=2;
	}

	while (1);
}
</file>
\\
As you may have noticed, we didn't declared the ''main'' symbol. That's because we  will not make use of the standard C libaries nor the low-level initialisation code intended to boards.\\
Having no default libraries means that the loader will try to find the ''_start'' symbol (which in turn is supposd to call the ''main'' symbol), so we declare it.\\

However, we ought to specifiy to the linker that it ought not to use all the default libraries: ''Project --> Properties''\\

{{ :arm:arm_eclipse_nodefaultlibs.png?direct&700 | No startup nor default C libraries.}}
\\
Next step is to build the binaries for the **debug** target (default). Eclipse console ought to display something that ought to looks like this:\\

{{ :arm:arm_eclipse_build.png?direct&700 |The build process.}}
\\
Now, we ought to setup the debug configuration. To do that, select the ''[arm/le]'' binary ...\\

{{ :arm:arm_eclipse_debugsetup0.png?direct&200 |Select binary}}
\\
... then right click ''Debug As --> Debug Configurations'' and create a new ''C/C++ application'' debug configuration (double click)\\

{{ :arm:arm_eclipse_debugsetup1.png?direct&700 |New C/C++ application debug configuration}}
\\
Now, a very important step is to specify the way Eclipse will call the GNU ARM debugger ''arm-eabi-gdb''.\\

<WRAP center round important 60%>
<del>GDB (DSF) Create Process Launcher</del>\\
Standard Create Process Launcher
</WRAP>

{{ :arm:arm_eclipse_debugsetup3.png?direct&400 |The way debugger is launched.}}
\\
The last setup step is to specify the GDB itself along with its init script and some other things as shown below:\\

{{ :arm:arm_eclipse_debugsetup4.png?direct&700 |ARM debugger with init script and breakpoint.}}
\\
<WRAP center round info 60%>//**__arm-simulator.gdbinit configuration file__**//
This file contains some hooks to make the arm-simulator to work within eclipse\\
<code>set backtrace limit 10
target sim
load</code>
</WRAP>
\\
Upon debug launch, you will be switched to the **Debug perspective**

{{ :arm:arm_eclipse_simulator.png?direct |ARM simulator within Eclipse.}}
\\
In this debug session, we added the following **views**:\\

  * registers | ''Window --> Show View --> Registers'',
  * disassembly code | ''Window --> Show View --> Disassembly''

===== JTAG-OpenOCD =====
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.\\

//to be continued ;)//