Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764235AbXFGPl2 (ORCPT ); Thu, 7 Jun 2007 11:41:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754815AbXFGPlV (ORCPT ); Thu, 7 Jun 2007 11:41:21 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:2488 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750923AbXFGPlU (ORCPT ); Thu, 7 Jun 2007 11:41:20 -0400 X-AuthUser: davidel@xmailserver.org Date: Thu, 7 Jun 2007 08:41:18 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@alien.or.mcafeemobile.com To: Alan Cox cc: Linux Kernel Mailing List , Linus Torvalds , Andrew Morton , Ulrich Drepper , Ingo Molnar , Eric Dumazet Subject: Re: [patch 7/8] fdmap v2 - implement sys_socket2 In-Reply-To: <20070607110623.53322dae@the-village.bc.nu> Message-ID: References: <20070606235906.72439d16@the-village.bc.nu> <20070607001932.35c9591c@the-village.bc.nu> <20070607110623.53322dae@the-village.bc.nu> X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1913 Lines: 39 On Thu, 7 Jun 2007, Alan Cox wrote: > > I don't think it's a matter of versioning. Many userspace libraries > > expects their fds to be compact (for many reasons - they use select, they > > use them to index 0-based arrays, etc...), and if the kernel suddendly > > starts returning values in the 1<<28 up arena, they sure won't be happy. > > So I believe that the correct way is that the caller specifically selects > > the feature, leaving the legacy fd allocation as default. > > I don't understand the connection between this paragraph (with which I > agree) and the urge to add a ton of ugly syscall hacks. "Caller > specifically selects feature" - > prctl(). Libraries get unhappy -> > linker issue. I meant, caller specifically selects the feature, on a per-fd basis. If you select the task flag runtime, then all the allocated fds will be in the non-sequential area. Even fds allocated inside the library code, with libraries not expecting this. I fail to understand how a linker can nicely solve this. If my app is using, for its own reasons, fds in the non-sequential area, and library XYZ internally uses fds and does not like them in that area, I still want to link to that library. As long as I do not pass my fds to the library ("XYZ internally .."), this must still work. The contrary is also true. If my app is not non-sequential fd aware, and my library wants to use them in order to keep them alive from apps doing the for-each-fd-close loop, with a per-fd policy, you can still mix them together. Or are you planning to have two sets of each userspace (userspace is not only glibc, there's other stuff too) libraries? - Davide - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/