devkitARM is a complete toolchain to allow development on various systems, such as for DS, GBA and GP32.

Release notes:

The latest release of the ARM toolchain is now available. There are a number of improvements:

binutils updated to 2.18.50
gcc updated to 4.3.0
grit updated to 0.8
ndstool now uses default.arm7 from libnds directory
newlib multibyte code enabled with C-UTF8 locale

devkitPro Updater 1.4.6 now downloads and installs the default.arm7 file used for arm9 only projects separately from libnds. This will allow us to maintain a much improved default arm7 core which will later include built in wifi support.

As usual, windows users should run the updater which will update itself, make sure you add the new default arm7 when shown the update list.

http://www.devkitpro.org/