Hello,
I'm currently looking at the virtex-4 configuration details and have a question about FDRI writes in the virtex4.
My reference point is the virtex-2 configuration. In the virtex-2 configuration, FDRI writes always include a pad frame (except in the MFWR write case, but that's not what i'm looking at).
Virtex-4 documentation makes no hint at such a frame. Indeed, uncompressed bitstreams show that the exact number of frames are written to the FDRI -- no pad frame there.
However, compressed bitstreams do not show such behaviour: FDRI writes of isolated configured portions of the design seem to show pad frames being written (the last frame's FAR value has already been programmed earlier). I'm left guessing that either the bitstream programs some frames twice (unlikely), or there's some machine state condition that i'm missing, which indicates whether or not pad frames are needed during FDRI writes on the virtex-4.
Can someone enlighten me on this?
Kind regards, Jean-Baptiste