From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH 080/493] fddi: remove use of __devexit_p Date: Wed, 21 Nov 2012 16:23:37 -0800 Message-ID: <20121122002337.GA16151@kroah.com> References: <1353349642-3677-1-git-send-email-wfp5p@virginia.edu> <1353349642-3677-80-git-send-email-wfp5p@virginia.edu> <20121119192949.GA16976@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Bill Pemberton , netdev@vger.kernel.org To: "Maciej W. Rozycki" Return-path: Received: from mail-da0-f46.google.com ([209.85.210.46]:37523 "EHLO mail-da0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965062Ab2KVTXm (ORCPT ); Thu, 22 Nov 2012 14:23:42 -0500 Received: by mail-da0-f46.google.com with SMTP id p5so2312343dak.19 for ; Thu, 22 Nov 2012 11:23:41 -0800 (PST) Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Nov 21, 2012 at 11:49:50PM +0000, Maciej W. Rozycki wrote: > Greg, > > > > I have unconfused myself now, so please replace the above with the > > > following question: what about configurations (e.g. buses) that not > > > support hotplug at all? For example apart from PCI the defxx driver > > > concerned here supports the TURBOchannel bus that by design does not have > > > the concept of live option card removal (no such circuitry). So should > > > now the precious memory be wasted on systems that will never ever handle > > > hotplug? > > > > CONFIG_HOTPLUG is always enabled now, so that's not an option anymore. > > And again, a user can "hot unbind" a driver from a device from > > userspace, no matter if the bus physically supports it or not. > > Hmm, what purpose does this serve for devices that cannot be physically > removed? If there is none, shouldn't that policy be set by individual > drivers or platform even? Even if HOTPLUG as a whole is unconditional (I > suppose the amount of space core support itself takes is much less to what > driver code can). > > TURBOchannel, although valid, is an old exotic case that might not be > worth arguing for, except for purity maybe. But there are surely many > contemporary systems out there that are known they are never going to > support hot device replacement. Consider most of the embedded systems for > example, where devices may even physically be cast into a single SOC (with > no prospect of chipping off any pieces ever ;) ), that certainly could not > care less of device replacement, but they do care a lot about memory > consumption. Even those don't care about less than 5k of memory, do they? > Was this implication considered, discussed and diregarded as not > important enough compared to benefits from hardcoding HOTPLUG support? Yes, I don't know of any modern system that does not enable CONFIG_HOTPLUG, do you? > I'm seriously asking for a pointer, not trying to cause any stir-up -- > regrettably I fail to follow most discussions these days, but I would like > to know what the background behind this decision was. Thanks a lot! See Russell's response in this thread for details if you are curious. thanks, greg k-h