At first sight VFP4 is sufficient, im focusing on DSP instructions because FPU is optional on Cortex-M4 (there is Cortex-M4 and Cortex-M4F) so on cortex_m4_initfn im not adding ARM_FEATURE_VFP4 (right now I dont have the time to fully check this). I'd like to point out that i did not implement any board, so on armv7m_init function of armv7m.c the cpu_model is still cortex-m3 as it should, as far as i know the board will use this function to name cpu_model (i.e stellaris.c will call armv7m_init and cpu_model will be "cortex-m3")
2015-05-26 14:34 GMT-03:00 Peter Maydell <peter.mayd...@linaro.org>: > On 26 May 2015 at 18:13, aurelio remonda <aurelioremo...@gmail.com> wrote: > > There are 85 instructions labeled as DSP (all of them thumb2), im just > > testing on disas_thumb2_insn if the feature is enabled before the > > instruction is generated.i.e. > > if (!arm_dc_feature(s, ARM_FEATURE_DSP)) goto illegal_op; > > Im using DDI0439B_cortex_m4_r0p0_trm - Cortex-M4 Technical Reference > Manual > > (there's s table of dsp instructions on page 33) and this > > http://www.lpcware.com/system/files/1100969_Cortex-Inst.jpg as > reference. > > Ah, right. I suggest we call this > ARM_FEATURE_THUMB_DSP /* DSP insns supported in the Thumb encodings */ > and in arm_cpu_realizefn() just after the bit where we set ARM_FEATURE_CBAR > you want: > if (arm_feature(ARM_FEATURE_THUMB2) && !arm_feature(ARM_FEATURE_M)) { > set_feature(env, ARM_FEATURE_THUMB_DSP); > } > > because all A and R profile cores with Thumb2 have these instructions. > You'll also want to set the THUMB_DSP feature bit for your new M4 > core in its cortex_m4_initfn(), and that should be enough. > > (I think "THUMB_DSP" is better than "DSP" because in the ARM encoding > we won't look at this feature bit, because the presence of the insns > is determined by the architecture version -- some come in in v5 and the > rest in v6.) > > For floating point, is it sufficient to turn on ARM_FEATURE_VFP4 for > the M4, or does that enable too much? > > thanks > -- PMM >
