Is there any way to active\deactive the Dual issue feature?
What “dual -issue” feature are you asking about? The cpu on the HiFive1 Rev B board has a single issue pipeline.
I’m referring to FU740-C000 - this one has Dual-issue in-order 64-bit execution pipeline
Is it possible to turn Dual-issue OFF by SW?
FYI, we have a separate channel for HiFive Unmatched (which includes FU740-C000):
This channel is for a different product.
Regarding your question, I think the answer is effectively No. Different types of instructions are issued on each of the two pipelines, so disabling one of the pipelines would cripple the machine.