From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerrit Renker Date: Mon, 07 Apr 2008 07:46:19 +0000 Subject: Re: compatibility issues Message-Id: <20080407074619.GF6146@gerrit.erg.abdn.ac.uk> List-Id: References: <200804062210.03693.tomasz@grobelny.oswiecenia.net> In-Reply-To: <200804062210.03693.tomasz@grobelny.oswiecenia.net> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: dccp@vger.kernel.org | Recently I switched to the origin/dccp branch of dccp test tree. And noticed | that dccp communication between kernel build from origin/dccp branch and | kernel build from origin/master branch is not possible. When kernels are from | the same branch (no matter if it is origin/dccp or origin/master) the problem | does not occur. Is it a known issue? | -- The test tree contains fixes for bugs that are in the mainline kernel and is thus not bug-compatible with the mainline tree (origin/master). I can't tell from your description where exactly the communication is "not possible", but one likely cause is the feature negotiation. This is definitively broken in origin/master: when setting up the receiver with CCID-2, and the sender with CCID-3, both will end up using these CCIDs with correspondingly horrible performance; since the origin/master implementation performs "feature announcement" rather than "feature negotiation". The test tree has a full implementation of feature negotiation and will refuse to start communication if parameters are incompatible. It may allow communication to an origin/master implementation as long as the origin/master implementation conforms in its behaviour to RFC 4340, section 6. Thus the "communication not possible" is not unconditional. If you think you have found a bug, please provide more detailed information. The University of Aberdeen is a charity registered in Scotland, No SC013683.