Re: [PATCH 4/9] proto.md: Document historic values for magics, reserve new value
On Fri, Jan 21, 2022 at 06:57:06PM +0100, Manfred Spraul wrote:
> From: Manfred Spraul <manfred.spraul@de.bosch.com>
>
> Right now:
> - The historic values for NBD_REQUEST_MAGIC and NBD_REPLY_MAGIC are
> just documented in nbd.h, without any background.
> - The new value that is now used for internal use by nbd-server is
> not documented at all.
>
> Resolve that:
> - Add all required information to proto.md.
> - Remove the reserved magic values from nbd.h: proto.md is the
> authorative source, double storage doesn't help.
>
> Signed-off-by: Manfred Spraul <manfred.spraul@de.bosch.com>
> ---
> doc/proto.md | 12 ++++++++++++
> nbd.h | 1 -
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/doc/proto.md b/doc/proto.md
> index 3a877a9..81ac755 100644
> --- a/doc/proto.md
> +++ b/doc/proto.md
> @@ -458,6 +458,18 @@ SHOULD wait until there are no inflight requests first.
> The client and the server MUST NOT initiate any form
> of disconnect other than in one of the above circumstances.
>
> +#### Reserved Magic values
> +
> +The following magic values are reserved and must not be used
> +for future protocol extentions:
extensions
> +
> +0x12560953 - Historic value for NBD_REQUEST_MAGIC, used
> + until Linux 2.1.116pre2.
> +0x96744668 - Historic value for NBD_REPLY_MAGIC, used
> + until Linux 2.1.116pre2.
> +0x25609514 - Used by nbd-server to store data log flags in the
> + transaction log. Never sent from/to a client.
> +
Seems reasonable to me.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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