DM8127 - what code is running on the DSP C674x by default?

We are working on the APPRO camera built with the TMS320DM8127.

I've copied the diagram and part of the message from http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/100/t/264285.aspx

step3:

after VPSS_M3, data flow can be divided two parts.

1. yuv420sp given to VIDEO_M3 for encoder like H264 or JPEG,MPEG4.
2. data given to DSP_C674x for video analytics.

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I still have the following questions for which I've searched for answers:

1. What is running on the C674x by default? Is it active on power-up of the APPRO evaluation camera?
2. How do I write code to the DSP?
3. If it's not running, how do I allow the DSP to run and accept images?
4. How are output from imaging functions received on the ARM? I understand that MessageQs are used. Is this correct?
5. Are there any examples with Linux code for the ARM and C code for the DSP?

Thanks,

Mechi