From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 29 Jun 2000 11:52:14 +0100 From: "Stephen C. Tweedie" Subject: Re: kmap_kiobuf() Message-ID: <20000629115214.B3914@redhat.com> References: <11270.962206915@cygnus.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <11270.962206915@cygnus.co.uk>; from dwmw2@infradead.org on Wed, Jun 28, 2000 at 04:41:55PM +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: David Woodhouse Cc: linux-kernel@vger.rutgers.edu, linux-mm@kvack.org, sct@redhat.com, riel@conectiva.com.br List-ID: Hi, On Wed, Jun 28, 2000 at 04:41:55PM +0100, David Woodhouse wrote: > I think it would be useful to provide a function which can be used to > obtain a virtually-contiguous VM mapping of the pages of an iobuf. Perhaps, but I really would rather resist this. The whole point of kiobufs is to let you deal cleanly with thinks which are unaligned by doing page lookups. They are specifically intended to _avoid_ nasty VM tricks. Adding kiobuf support for things like memcpy_to/from_kiobuf is something I will do, but kiobufs are there to help get people out of the mindset that all buffers are virtually contiguous in the first place! It would be fairly easy to add kiobuf support for this, but it would make it harder to get the diffs past Linus (who really wants vmalloc to go away as much as possible). I'm open to arguments, but "I coded this way in the past and I'd rather the kernel did ugly things to let me keep coding this way in the future" isn't the sort of reasoning that helps me to get new functionality past Linus's sanity filters. :-) Cheers, Stephen -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/