From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33796) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ao1Jo-0007g7-S8 for qemu-devel@nongnu.org; Thu, 07 Apr 2016 00:13:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ao1Jj-0005gf-SO for qemu-devel@nongnu.org; Thu, 07 Apr 2016 00:13:20 -0400 Received: from resqmta-po-03v.sys.comcast.net ([96.114.154.162]:57031) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ao1Jj-0005gB-NO for qemu-devel@nongnu.org; Thu, 07 Apr 2016 00:13:15 -0400 From: Eric Blake Date: Wed, 6 Apr 2016 22:12:10 -0600 Message-Id: <1460002330-20965-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH] doc: Revert swap of NBD_REP_SERVER fields in NBD_OPT_GO List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: nbd-general@lists.sourceforge.net Cc: qemu-devel@nongnu.org Commit 730c5830 included a reordering of the fields of NBD_REP_SERVER, under the guise of putting the variable-sized data last. However, this makes life harder for sharing code - the regular NBD_REP_SERVER used by NBD_OPT_LIST already has _two_ variable-sized fields: name, and an optional string of additional information, and the wording of the surrounding text implied that NBD_OPT_GO was just re-purposing the tail end as binary data instead of a string, not reorganizing all the fields. Furthermore, sticking the same fields last in both NBD_OPT_GO and NBD_OPT_EXPORT_NAME means that any other future handshake extension that sends a few more bytes of data behind the transmission flags can do so in both places without reordering the first half of NBD_REP_SERVER (such an extension is already envisioned, where the client and server agree to have the server advertise minimum, preferred, and maximum block sizes). Signed-off-by: Eric Blake --- I'm trying to implement NBD_OPT_GO in qemu, and found the original order easier to support than the swapped order. doc/proto.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/doc/proto.md b/doc/proto.md index 7b36be4..0775360 100644 --- a/doc/proto.md +++ b/doc/proto.md @@ -744,13 +744,13 @@ Therefore these commands share common documentation. in place of the default UTF-8 free-form string). The option reply length MUST be *length of name* + 14, and the option data has the following layout: - - 64 bits, size of the export in bytes (unsigned) - - 16 bits, transmission flags. - 32 bits, length of name (unsigned) - Name of the export. This name MAY be different from the one given in the `NBD_OPT_INFO` or `NBD_OPT_GO` option in case the server has multiple alternate names for a single export, or a default export was specified. + - 64 bits, size of the export in bytes (unsigned) + - 16 bits, transmission flags. The server MUST NOT fail an NBD_OPT_GO sent with the same parameters as a previous NBD_OPT_INFO which returned successfully (i.e. with -- 2.5.5