What determines the automatic processor/io memory ratio? I had two 2691s, same modules installed, same IOS versions and amount of memory, and pretty much the same configs. Yet, they had different ratios. Both did not have any memory commands. One had 10 MB reserved for IO, while the other one had 32 MB.
I forced one to be like the other using memory-size iomem command, but I was curious what factors affect how the default memory reserves are laid out.