So it is. It would've been much clearer to mention that at the beginning when it's first introduced, since it's not commented like the other instructions and I first thought it was a left-over placeholder.
That said, it must be a very old GDB since I've otherwise not ever seen a NOP as the very first instruction of any nontrivial program in all these years... maybe two NOPs in the early days for patching, but that's about it.
I agree the structure of some of my explanations could have been a bit better. The book I was using as a basis was from the mid-90s so it would be a version of GDB from 20 years ago that requires the NOP.
