Setting up a Toolchain

First download a buildroot.tar.gz from here. Extract and run make menuconfig :


$ cd $PROJ_ROOT
$ wget http://buildroot.uclibc.org/downloads/snapshots/buildroot-snapshot.tar.bz2 
$ tar -jxf buildroot-snapshot.tar.bz2
$ mv buildroot-snapshot.tar.bz2 archives/
$ cd buildroot
$ make menuconfig

The following is what I changed from the default:

Target Architecture: mipsel
Build Options -> Number of Jobs to Run Simultaneously: 3
Toolchain Options -> Kernel Headers: Linux 2.6.9 (not sure about this, it might cause issues later?)
Package Selection for the Target: Uncheck BusyBox (I built it separately later)
Package Selection for the Target: zlib (important if you want to build dropbear)
Target Options: Uncheck ext2 root filesystem

Now run "make". Wait for the first download to complete the you will be asked four questions.


$ make
  <snip>
*
* uClibc Configuration
*
Target Architecture
  1. alpha (TARGET_alpha)
  2. arm (TARGET_arm)
  3. bfin (TARGET_bfin)
  4. cris (TARGET_cris)
  5. e1 (TARGET_e1)
  6. frv (TARGET_frv)
  7. h8300 (TARGET_h8300)
  8. i386 (TARGET_i386)
  9. i960 (TARGET_i960)
  10. m68k (TARGET_m68k)
  11. microblaze (TARGET_microblaze)
> 12. mips (TARGET_mips)
  13. nios (TARGET_nios)
  14. nios2 (TARGET_nios2)
  15. powerpc (TARGET_powerpc)
  16. superh (TARGET_sh)
  17. sparc (TARGET_sparc)
  18. v850 (TARGET_v850)
  19. x86_64 (TARGET_x86_64) (NEW)
choice[1-19?]: 12
*
* Target Architecture Features and Options
*
Target Processor Architecture
> 1. Generic (MIPS I) (CONFIG_MIPS_ISA_1) (NEW)
  2. MIPS II (CONFIG_MIPS_ISA_2) (NEW)
  3. MIPS III (CONFIG_MIPS_ISA_3) (NEW)
  4. MIPS IV (CONFIG_MIPS_ISA_4) (NEW)
  5. MIPS32 (CONFIG_MIPS_ISA_MIPS32) (NEW)
  6. MIPS64 (CONFIG_MIPS_ISA_MIPS64) (NEW)
choice[1-6?]: 5
Target Processor Endianness
> 1. Little Endian (ARCH_LITTLE_ENDIAN) (NEW)
  2. Big Endian (ARCH_BIG_ENDIAN) (NEW)
choice[1-2?]: 1
Target CPU has a memory management unit (MMU) (ARCH_HAS_MMU) [Y/n/?] (NEW) y

Hit Enter to the first question (about the Target Architecture - you should have selected it in make menuconfig). Choose option 5 for the second (CONFIG_MIPS_ISA_MIPS32). Choose option 1 (ARCH_LITTLE_ENDIAN) for the third question and Y for ARCH_HAS_MMU. Now go and grab a drink, the required components will be downloaded and built.

Ok, once that is done you should have a shiny new toolchain sitting in ./build_mipsel/staging_dir/bin . You'll probably want to add that to your $PATH by adding the following lines to your .bashrc (make sure they are AFTER the PROJ_ROOT lines):


PATH=$PATH:$PROJ_ROOT/buildroot/build_mipsel/staging_dir/bin
export PATH

IMPORTANT! You need to symlink /opt/brcm/hndtools-mipsel-linux-3.0 to $PROJ_ROOT/builroot/build_mipsel/staging_dir to fix some problems related to hard coded paths.


$ cd opt
$ mkdir brcm
$ ln -s $PROJ_ROOT/buildroot/build_mipsel/staging_dir brcm/hndtools-mipsel-linux-3.0

Bob Keyes notes:

I've figured out something about the toolchain - it doesn't handle dependencies very well. I was getting hung up because I was trying to build nano, which depends on ncurses. But simply using make menuconfig and adding ncurses after finding this out did not help -- you have to make the dependencies first, then run through again with the dependants selected.

Next: Set up a Root File System