From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamie Lokier Subject: Re: [patch 1/4] Configure out AIO support Date: Tue, 5 Aug 2008 19:26:07 +0100 Message-ID: <20080805182607.GA28513@shareable.org> References: <20080731092703.661994657@free-electrons.com> <20080731093220.690886851@free-electrons.com> <20080731100929.GA9206@mx.loc> <20080731101219.GC4221@cs181140183.pp.htv.fi> <20080731224222.GB9208@mx.loc> <20080805181536.GH22895@cs181140183.pp.htv.fi> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20080805181536.GH22895@cs181140183.pp.htv.fi> Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Adrian Bunk Cc: Bernhard Fischer , Thomas Petazzoni , linux-kernel@vger.kernel.org, linux-embedded@vger.kernel.org, michael@free-electrons.com, Matt Mackall , bcrl@kvack.org, linux-aio@kvack.org, akpm@linux-foundation.org Adrian Bunk wrote: > On Fri, Aug 01, 2008 at 12:42:22AM +0200, Bernhard Fischer wrote: > > On Thu, Jul 31, 2008 at 01:12:19PM +0300, Adrian Bunk wrote: > > >On Thu, Jul 31, 2008 at 12:09:29PM +0200, Bernhard Fischer wrote: > > >> On Thu, Jul 31, 2008 at 11:27:04AM +0200, Thomas Petazzoni wrote: > > >> >This patchs adds the CONFIG_AIO option which allows to remove support > > >> >for asynchronous I/O operations, that are not necessarly used by > > >> >applications, particularly on embedded devices. As this is a > > >> >size-reduction option, it depends on CONFIG_EMBEDDED. It allows to > > >> >save ~7 kilobytes of kernel code/data: > > >> > > >> Shouldn't this also make sure not to install aio_abi.h or at least an > > >> empty aio_abi.h? > > > > > >The userspace headers are independent of any kernel configuration > > >(except for the architecture). > > > > I beg to disagree: > > internals as exposed by e.g. aio_abi.h are impl dependent. Noone except > > the impl and it's users are interrested in it. > >... > > That's utter bullshit. > > The contents of aio_abi.h is a kernel<->userspace ABI that mustn't ever > change. [1] Case in point: I want to be able to compile an application for embedded Linux which *can use* Linux-AIO, but can also run on a kernel which has Linux-AIO removed by this patch. I still want to compile the application with that capability, in case it's run on another kernel with it enabled. I shouldn't have to have a separate, special kernel with all options enabled, just to compile applications that run on multiple kernels and use run-time features when available. Just like all the other kernel<->userspace interfaces, the header files (including their presence) shouldn't depend on kernel configuration at all. -- Jamie