Im replying this cause i made a mistake asking to someones private mail, sorry:
> OK, another question. How come if Cortex-M3 doesnt support DSP instructions
> qemu understand them? I tried some of them with an stellaris lm3s6965evb. I
> do understand that they were implemented for the A profile cores, but not
> for M ones. Is this a bug or im missing something?

If our cortex-m3 model doesn't fault on an instruction that's not
implemented in the M3 then that's a bug, yes. If you provide more
detail we can fix it.

2015-05-05 9:52 GMT-03:00 aurelio remonda <aurelioremonda@gmail.com>:

Hi, i would like to to add support for cortex-m4 on qemu. Most features of the Cortex-M3 and M4 are the same with the significant difference that Cortex-M4 has DSP extensions and optional FPU. Even so, i really need some pointers for this (im a newbie on qemu devel). I found out that qemu can manage dsp instructions such as ADD16, ASX, SAX, etc. and all their combinations with suffixes (u, s, sh, etc.), so half (if not all) of the work is done.

How should I go about this? What's the standard procedure for adding a new CPU, even if it's so similar to the existing ones? That is, which are the relevant functions/files that I should modify, and so on.

Thanks a lot!