Re: [Libguestfs] [PATCH v2 3/6] spec: Add NBD_OPT_EXTENDED_HEADERS
On Fri, Mar 03, 2023 at 04:36:41PM -0600, Eric Blake wrote:
On Wed, Feb 22, 2023 at 11:49:18AM +0200, Wouter Verhelst wrote:
> On Mon, Nov 14, 2022 at 04:46:52PM -0600, Eric Blake wrote:
[...]
> > + Note that even when extended headers are in use, the
client MUST be
> > + prepared for the server to use either the compact or extended chunk
> > + type, regardless of whether the client's hinted effect length was
> > + more or less than 32 bits; but the server MUST use exactly one of
> > + the two chunk types per negotiated metacontext ID.
>
> Is this last paragraph really a good idea? I would think it makes more
> sense to require the new format if we're already required to support it
> on both sides anyway.
My proof of implementation was easier to code when I didn't have to
resize the block status reply sizing in the same patch as adding the
64-bit headers. But if you think requiring the 64-bit reply type
always (and forbidding the 32-bit reply) when extended headers are in
force, that's also possible.
Intuitively, this sounds off. It would seem to me that it's easier to do
if you don't have to have a conditional on each received data packet.
But maybe I'm missing something -- I haven't done an implementation yet,
anyway.
--
w(a)uter.{be,co.za}
wouter(a){grep.be,fosdem.org,debian.org}
I will have a Tin-Actinium-Potassium mixture, thanks.