Am 20.06.2010 12:51, schrieb Avi Kivity: > On 06/18/2010 03:59 PM, Markus Armbruster wrote: >> The code is pretty confused about format vs. protocol, and so are we. >> Let's try to figure them out. >> >> From cruising altitude, all this format, protocol, stacking business >> doesn't matter. We provide a bunch of arguments, and get an image. >> >> If you look more closely, providing that image involves sub-tasks. One >> is to haul bits. Another one is to translate between bits in different >> formats. >> >> Working hypothesis: >> >> * A protocol hauls image bits. Examples: file, host_device, nbd. >> >> * A format translates image formats. Examples: raw, qcow2. >> >> > > Is there a reason to make the distinction? Is there a reason to expose > the distinction to the user?
There are good reasons to make that distinction internally. There's no need to expose it to the user - the question is if it helps or not. Historically, format and protocol are defined like this (so in fact they are user-visible currently): * A format is what you specify as file=... * A protocol is what is encoded in the file name And I think as long as you have exactly one format and one protocol, it's easier to understand than a chain of block drivers. But that's really just about how to expose it. Kevin
