Does it mean it can't be switched to lower frequency ?
Or the 1GHz just represents the base frequency, the system counter still can switch to lower frequency such as 50MHz, 100MHz, etc ?
The manual always says "from 8.0 to 8.5 ..." whenever it comes to lower frequencies.Though I see that the "note" you are referring might be intended for 8.0 to 8.6.
Maybe some ARM employee can fill the gap. ;-)