This document provides an overview of building an ARM toolchain for cross-compilation. It discusses ARM architectures like ARM7, ARM9 and ARM11. It explains the steps of cross-compilation using gcc, as and ld. It covers specifying the target architecture, EABI targets, and configuring options. It also describes setting up the build environment, compiling binutils, glibc, gcc and bootstrapping gcc to build a cross-compiler toolchain.

1. Building your own toolchain
~ Chaitannya Mahatme

2. Overview of ARM architectures.

ARM 7

ARM 9

ARM 11

3. ARM7TDMI

ARM7TDMI
(ARM7+Thumb+Debug+Multiplier+ICE)

This generation introduced the Thumb 16­
bit instruction set
Audio controller in the SEGA Dreamcast

D­Link DSL­604+ Wireless ADSL Router.

iPod ,iRiver

Most of Nokia's mobile phone range.

4. ARM 9

ARM moved from a von Neumann
architecture (Princeton architecture) to a
Harvard architecture with separate
instruction and data bus (and caches),
significantly increasing its potential speed.

Most important change was introduction of
MMU, POSIX complaint OS could be
ported.

All smart phones

5. ARM 11

SIMD instructions which can double
MPEG­4 and audio digital signal
processing algorithm speed

Cache is physically addressed, solving
many cache aliasing problems and
reducing context switch overhead.

TI OMAP2 series processors.

All touch based smart phones.

6. Steps of Cross­Compilation

gcc: Run the cross­compiler on the host
machine to produce assembler files for the
target machine.

as: Assemble the files produced by the
cross­compiler.

ld: Link those files to make an executable.
You can do this either with a linker on the
target machine, or with a cross­linker on
the host machine.

7. Specifing target for your toolchain

arm­linux

Armv4l : This makes support for the ARM
v4 architecture, as used in the StrongARM,
ARM7TDMI, ARM8, ARM9.

Armv5l : This makes support for the ARM
v5 architecture, as used in the XScale and
ARM10.

8. EABI target

arm­eabi

arm­none­eabi

In practice the target name makes almost
no practical difference to the toolchain you

9. Other EABI options

arm­none­gnueabi: this is the name as arm­
none­eabi (specific to GNU compiler)

arm­unknown­eabi: bare metal

arm­linux­eabi: Designed to be used to
build programs with glibc under a Linux
environment. This would what you would
use to build programs for an embeded
linux ARM device.

10. CPU options

arm7, arm7tdmi, arm720t,

arm9', arm9e, arm920, arm920t

arm1136j­s, arm1176jz­s

11. Other configure options

­­enable­interwork This allows for
assembling Thumb and ARM code mixed
into the same binaries (for those chips that
support that)

­­enable­multilib Multilib allows the use of
libraries that are compiled multiple times
for different targets/build types.

12. EABI for Linux

GNU EABI is a new Application Binary
Interface (ABI) for Linux a.k.a Embedded
ABI.

EABI specifies standard conventions for file
formats, data types, register usage, stack
frame organization, and function
parameter passing of an embedded
software program.

13. Why switch to EABI?

Compilers that support the EABI create
object code that is compatible with code
generated by other such compilers, thus
you can link libraries generated with with
object code generated with a different
compiler.

14. 
Allows use of optimized hardfloat
functions with the system's softfloat
libraries

Uses a more efficient syscall convention,
hence faster performance.

Since it's a newly adopted standard, will be
more compatible with future tools.

15. Setting up build envoirnment.

Preferably use virtual box / Vmware.

Create a new user for the installation.

Set up the configure parameters in the
.profile

Create separate dir for build and source.

Set PREFIX dir

16. Compilation process

Binutils

glibc

gcc

gdb

17. Bootstrapping gcc

Install all the dependencies.

The list of dependencies is on gcc.org

Mandatory dependencies are GMP and
MPFR.

The configure option ­­with­newlib tells gcc
we are using newlib (see below) and
­­without­headers tells GCC not to rely on
any C library (standard or runtime) being
present for the target.

18. Installing glibc

Before doing any configuring or compiling,
you must set the C compiler that you’re
using to be your cross­compiler, otherwise
glibc will compile as a horrible mix of ARM
code and native code

Make all­gcc.

Make install­gcc

19. Installing gcc: Part II

Make

Make install

Add compiler to path variable

20. Get more info on
 http://wiki.openarmlab.org/

http://wiki.openarmlab.org/index.php?
title=Building_your_own_toolchain

21. That's all Folks … Thank you