From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965581AbbEMPq1 (ORCPT ); Wed, 13 May 2015 11:46:27 -0400 Received: from mail-qc0-f176.google.com ([209.85.216.176]:36467 "EHLO mail-qc0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964839AbbEMPqY (ORCPT ); Wed, 13 May 2015 11:46:24 -0400 Date: Wed, 13 May 2015 11:46:20 -0400 From: Tejun Heo To: David Miller Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, penguin-kernel@I-love.SAKURA.ne.jp, sd@queasysnail.net Subject: Re: [PATCH 4/4] netconsole: implement extended console support Message-ID: <20150513154620.GX11388@htj.duckdns.org> References: <1431362494-9874-5-git-send-email-tj@kernel.org> <20150511.132339.403868463230045095.davem@davemloft.net> <20150511203745.GI11388@htj.duckdns.org> <20150512.192322.2233784105592482987.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150512.192322.2233784105592482987.davem@davemloft.net> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, David. On Tue, May 12, 2015 at 07:23:22PM -0400, David Miller wrote: > Second question, is there an upper bound on this header size? > Because if there is, it seems to me that there is no reason why we > can't just avoid the fragmentation support altogether. > > The current code limits to 1000 bytes, and that limit seems arbitrary. > Obviously this code is meant to work on interfaces with an ethernet > MTU or larger. So you could bump the limit enough to accomodate the > new header size, yet still be within the real constraints. > > What do you think? Yeah, if we can bump the tx size enough to accomodate all messages, it'd be great. It can get fairly large tho. The absolute maximum right now is 8k. While regular prink message bodies are capped slightly below 1k, the dictionary printed through vprintk_emit() doesn't have such length limit. Another factor is that non-printables are escaped using \xXX and vprintk_emit() is supposed to be useable with transmitting binary data (like low level device error descriptors) although I'm not sure anybody is doing that yet. Thanks. -- tejun