On Wed, Oct 10, 2012 at 4:42 AM, Grant <emailgr...@gmail.com> wrote: > 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?
The errors are coming from an assembler file that is not part of the GCC sources. Are those instructions valid for Thumb2? I don't know. If they are valid, then the issue is with the assembler, which is not part of GCC; check the version of the GNU binutils that you have installed. If those instructions are not valid, then you need to change your source. Ian
