FPGA configuration - Multiple Device SelectMAP - sharing PROG line
Yes, if you share the prog_b line, then it is not possible to reset the devices individually, unless you do it from inside the FPGA design via the ICAP. If you want to be able to reset them independently, then don't share the prog_b line. In fact, what I would recommend doing is only sharing the data, clock, and rdwr pins and keeping CS, prog_b, init_b, and done separate. That way you can easily see which devices failed to configure, instead of that something failed to configure, but you can't tell which FPGA it was. The flip side is that there are some benefits from wiring I think init_b together in terms of ensuring that the FPGAs start up together, so maybe share init_b but not prog_b or done.