1. ELC-E - October 2010 - crosstool-NG
A (cross-)toolchain generator
Yann E. MORIN
To the attendance :
if you can read this,
then something is wrong!
;-)
(C) 2010 Yann E. MORIN

2. ELC-E - October 2010 - crosstool-NG
History
: cleanup-pass proposal
: cleanup-pass ended in rewrite
: first public release : 0.0.1
: first stable release : 1.0.0
: Mercurial repository
-> starting with original crosstool
-> add uClibc
---> not added upstream
---> port patch forward heavy-duty .
-> cleanup proposal
---> existing patches
---> deemed to complex
-> rewrite
---> as proof of concept of new feats
---> as a test-bed to push back
1.1.0
1.2.0
1.3.0
1.4.0
1.5.0
1.6.0
1.7.0
1.8.0
1.9.0
(C) 2010 Yann E. MORIN

3. ELC-E - October 2010 - crosstool-NG
Purpose
Build toolchains
Only build toolchains
Goals
-> toolchain not belong to system builders
---> think large devs teams
---> no need to build one toolchain each
---> many targets == many toolchains .
->
Easy to use
Easy to maintain
Easy to enhance
Act as a tutorial
(C) 2010 Yann E. MORIN

4. ELC-E - October 2010 - crosstool-NG
Make it easy to use :
standard behavior
Standard package
./configure
make
make install
Toolchain configuration
menuconfig
samples
Toolchain build
step by step
simplified log
-> do not confuse configuration
---> package
---> toolchain
(C) 2010 Yann E. MORIN

5. ELC-E - October 2010 - crosstool-NG
[INFO ] =============================================================
[INFO ] Installing shared core C compiler
[EXTRA] Configuring shared core C compiler
[EXTRA] Building shared core C compiler
[EXTRA] Installing shared core C compiler
[INFO ] Installing shared core C compiler: done in s (at 06:43)
[INFO ] Installing C library
[EXTRA] Copying sources to build dir
[EXTRA] Applying configuration
[EXTRA] Building C library
[EXTRA] Installing C library
[INFO ] Installing C library: done in 39.96s (at 07:23)
[INFO ] Installing final compiler
[EXTRA] Configuring final compiler
[EXTRA] Building final compiler
[EXTRA] Installing final compiler
[INFO ] Installing final compiler: done in s (at 09:48)
[INFO ] Cleaning-up the toolchain's directory
[INFO ] Stripping all toolchain executables
[EXTRA] Installing the populate helper
[EXTRA] Installing a cross-ldd helper
[EXTRA] Creating toolchain aliases
[EXTRA] Removing access to the build system tools
[EXTRA] Removing installed documentation
[INFO ] Cleaning-up the toolchain's directory: done in 1.88s (at 09:49)
[INFO ] Build completed at
[INFO ] (elapsed: 9:49.65)
[INFO ] Finishing installation (may take a few seconds)...
(C) 2010 Yann E. MORIN

6. ELC-E - October 2010 - crosstool-NG
Easy to maintain & enhance :
modular design
Isolated components
One config file
One build script
One patchset
API
Generic: get, extract and patch
Component-specific
C library: headers & start-files, full
Compiler: bootstrap 1 & 2, final
Alternatives
Architectures
C libraries
Kernels
...
Maintain, enhance
-> basically same thing
---> maintain == fix existing stuff
---> enhance == add new stuff .
Know what breaks, where it breaks
Know where to add new stuff
API
-> env vars
--> arch name, endianness, bitness...
-> hooks
---> helpers for generic hooks
---> Automatic inclusion to menuconfig
(C) 2010 Yann E. MORIN

7. ELC-E - October 2010 - crosstool-NG
ARCH description config file
config/arch/arm.in
# ARM specific configuration file
config ARCH_arm
select ARCH_SUPPORTS_32
select ARCH_DEFAULT_32
select ARCH_SUPPORTS_BOTH_MMU
select ARCH_DEFAULT_HAS_MMU
select ARCH_SUPPORTS_BOTH_ENDIAN
select ARCH_DEFAULT_LE
select ARCH_SUPPORT_ARCH
select ARCH_SUPPORT_CPU
select ARCH_SUPPORT_TUNE
select ARCH_SUPPORT_FPU
help
The ARM architecture, as defined by:
# ARM specific configuration file
choice
bool
prompt "Default instruction set mode"
default ARCH_ARM_MODE_ARM
config ARCH_ARM_MODE_ARM
prompt "arm"
help
Defaults to emitting instructions in the ARM mode.
config ARCH_ARM_MODE_THUMB
prompt "thumb (EXPERIMENTAL)"
depends on EXPERIMENTAL
Defaults to emitting instructions in the THUMB mode.
endchoice
config ARCH_ARM_MODE
string
default "arm" if ARCH_ARM_MODE_ARM
default "thumb" if ARCH_ARM_MODE_THUMB
config ARCH_ARM_INTERWORKING
prompt "Use Thumb-interworking"
default n
config ARCH_ARM_EABI
prompt "Use EABI"
default y
Set up the toolchain so that it generates
EABI-compliant binaries.
config ARCH_ARM_ABI_OK
depends on ! ARCH_ARM_EABI
select ARCH_SUPPORT_ABI
ARCH-specific options
config file
config/arch/arm.in.2
# Compute ARM-specific values
CT_DoArchTupleValues() {
# The architecture part of the tuple:
CT_TARGET_ARCH="${CT_ARCH}${target_endian_eb}"
# The system part of the tuple:
case "${CT_LIBC},${CT_ARCH_ARM_EABI}" in
*glibc,y) CT_TARGET_SYS=gnueabi;;
uClibc,y) CT_TARGET_SYS=uclibcgnueabi;;
*,y) CT_TARGET_SYS=eabi;;
esac
# Set the default instruction set mode
case "${CT_ARCH_ARM_MODE}" in
arm) ;;
thumb)
CT_ARCH_CC_CORE_EXTRA_CONFIG="--with-mode=thumb"
CT_ARCH_CC_EXTRA_CONFIG="--with-mode=thumb"
# CT_ARCH_TARGET_CFLAGS="-mthumb" ;;
if [ "${CT_ARCH_ARM_INTERWORKING}" = "y" ]; then
CT_ARCH_TARGET_CFLAGS+=" -mthumb-interwork" fi }
ARCH settings
script
scripts/build/arch/arm.sh
Same goes for all components .
Maybe build procedure is complex,
but adding to crosstool-NG is easy!
(C) 2010 Yann E. MORIN

8. ELC-E - October 2010 - crosstool-NG
Goodies
Companion libraries
gmp, mpfr, ppl, CLooG/ppl, mpc, libelf
Companion tools
auto-stuff et al.
Debug tools
gdb
ltrace, strace
dmalloc, D.U.M.A
Pre-configured sample toolchains
gmp, mpfr
---> mandatory, gcc >= 4.3, all frontends
---> mandatory, all gcc, fortran frontend .
mpc
---> mandatory, gcc >= 4.5, all frontends
ppl, cloog
---> optional, gcc >= 4.4, Graphite
libelf
---> optional, gcc >= 4.5, LTO
auto-stuff
---> either disapear, or make mandatory
gdb
---> cross, native & gdbserver, all static or shared
(C) 2010 Yann E. MORIN

9. ELC-E - October 2010 - crosstool-NG
Toolchain types
Different systems involved
build system that builds the toolchain
host system that runs the toolchain
target system the toolchain generates code for
Native build == host == target 
Cross build == host != target 
Cross-native build != host == target 
Canadian build != host != target 
build, host, target _SYSTEMS_ !!! .
Define _sytem_
(C) 2010 Yann E. MORIN

10. ELC-E - October 2010 - crosstool-NG
Steps : 23
libc_check_config
kernel_headers
gmp
mpfr
ppl
cloog
mpc
libelf
binutils
elf2flt
sstrip
cc_core_pass_1
libc_headers
libc_start_files
cc_core_pass_2
libc cc
libc_finish
libelf_target
binutils_target
debug
test_suite
finish
(C) 2010 Yann E. MORIN

11. ELC-E - October 2010 - crosstool-NG
Pros
Your choice of components versions
Optimised for your processor
Known patchset (if any)
Same sources for all targets
Upstream fixes easy to apply
Reproducible
Fits your build-system
(C) 2010 Yann E. MORIN

12. ELC-E - October 2010 - crosstool-NG
Status : what's already in?
11 Archs
5 C libraries
2 binary utilities
2 kernels
1 compiler
patchset
required by many components to build
controversy
Arch:
---> alpha, arm, avr32, blackfin, ia64,
---> m68k, mips, ppc, s390, sh, x86 .
C libs:
---> newlib, uClibc, eglibc, glibc, mingw
---> none !
binutils:
---> binutils, elf2flt
Kernels:
---> linux, mingw32
---> bare-metal !
Compiler:
---> gcc
(C) 2010 Yann E. MORIN

13. ELC-E - October 2010 - crosstool-NG
Future : short- and long-term plans
Add latest component versions
gcc, Linux, C libraries...
Consolidate backend-mode
currently used by buildroot
Consolidate canadian-crosses
needed before cross-native, and native
Look at LLVM / Clang
see how it all fits together
multi-lib
mingw32 & cygwin
build, host & target
...
(C) 2010 Yann E. MORIN

14. ELC-E - October 2010 - crosstool-NG
Thank you!
Yann E. MORIN
License for this paper: Creative Commons BY-SA 3.0
Source for this paper:
(C) 2010 Yann E. MORIN