thumb2 support

[Grant]

Hello, I'm working with the BeagleBone and gcc-4.5.4 on Gentoo.  If I
try to compile the 3.6 kernel with CONFIG_THUMB2_KERNEL, I get:

arch/arm/boot/compressed/head.S:127: Error: selected processor does
not support requested special purpose register -- `mrs r2,cpsr'
arch/arm/boot/compressed/head.S:134: Error: selected processor does
not support requested special purpose register -- `mrs r2,cpsr'
arch/arm/boot/compressed/head.S:136: Error: selected processor does
not support requested special purpose register -- `msr cpsr_c,r2'

This post indicates that mainline gcc does not currently support thumb2:

https://groups.google.com/d/msg/beagleboard/P52fgMDzp8A/vupzuh71vdYJ

However, this indicates that thumb2 has been supported since 4.3:

http://gcc.gnu.org/gcc-4.3/changes.html

Can anyone clear this up?

- Grant