[Arm-netbook] Kernel compiles with crosstool-ng

[Alec Ari]

Hi! Just thought I'd write in for other developers out there. The kernel source on alioth in the arm-netbook tree compiles just fine in the latest crosstool-ng release, with armv7-a as the arch, and cortex-a8 for the CPU tune (-mtune not -mcpu) option, hard float with 'neon' as the FPU, GCC 4.5.3 with Graphite Loop Optimizations, Binutils 2.21a with all plugins, and latest GMP, cloog, cloog-ppl, etc in the crosstool-ng config. Enable 128-bit long doubles is ON (Y), and disable PCH. __cxa_atexit is enabled (Y)

(Run on sentence here, sorry...) All Cortex A8 processors have hard floating point with NEON, and even though NEON doesn't strictly follow the IEEE 754 standard (like VFPv3), causing floating-point operations to not be used by GCC's auto-vectorization pass and a loss of precision, NEON has all the multimedia instructions that VFPv3 lacks, and if people need more precise code, they can use -funsafe-math-optimizations IF NECESSARY, making NEON a better choice (at least IMO.)

I have not tested the arm-netbook kernel with different options for crosstool-ng 1.13.2 but the options I used SHOULD be just fine for real A10 hardware (at least in a sane world.)

Perhaps somebody should try the same toolchain for the official allwinner code on github and see if that works too? :)

-Alec