Give more details about packet time stamps.

Give more details about packet time stamps.

Don't speak of "Ethernet" and "wire", as you might not be sniffing an
Ethernet or, indeed, any form of wired network.

Note that not only could there be a delay between the point at which the
interface is finished receiving the packet and when an interrupt is
delivered (whether due to bus delays, polling rather than immediate
interrupts being used, or delays in the CPU responding to the interrupt,
or more than one of those) but also a delay between the point at which
the kernel responds to the interrupt and the point at which it actually
applies a time stamp to the packet.