From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Snook Subject: Re: [PATCH] Change S390 anti-dependency to CONFIG_GENERIC_HARDIRQS dependency Date: Wed, 15 Oct 2008 12:48:56 -0400 Message-ID: <48F61EF8.20202@redhat.com> References: <48F52E89.9050104@redhat.com> <20081014.165211.53009170.davem@davemloft.net> <48F5345B.6060108@redhat.com> <20081014.221647.184282035.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: afleming@gmail.com, afleming@freescale.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from mx2.redhat.com ([66.187.237.31]:32822 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752269AbYJOQtN (ORCPT ); Wed, 15 Oct 2008 12:49:13 -0400 In-Reply-To: <20081014.221647.184282035.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: David Miller wrote: > From: Chris Snook > Date: Tue, 14 Oct 2008 20:07:55 -0400 > >> But then it will be much more of a pain to exclude the vast swath of >> irrelevant code in the kernel tree from your builds on these exotic >> architectures. Have you ever built a kernel on s390? > > That's totally irrelevant. > > Does S390 have ethernet or ethernet-like devices? If so, the someday > it might in fact might want to use something like phylib instead of > adding yet another implementation of programming a particular PHY > chip. Last I checked, s390 doesn't have any hardware that can't be shared between at least 64 guests. The most Linux will ever control on that hardware is a software channel, be it a channel to a disk controller, network controller, or application-specific offload engine. They don't really have NICs, more like a built-in router which can optionally fake layer 2 for the benefit of guests. > So in fact, something like phylib should be possible to enable even on > s390. > > And this current situation means s390 builds get less coverage, making > allmodconfig test builds (which the s390 folks are obviously doing > since they hit this originally reported build failure) less > useful than they could be. Currently, allmodconfig on s390 is cheap, because there's a miniscule amount of device driver code that can be enabled in Kconfig. If you enabled all those other drivers to build on s390, it would take *days* to complete an allmodconfig build natively or in an emulator. Forcing people to use cross-compilers to get things done at a reasonable pace would mean treating s390 differently from other architectures in multi-platform build systems, and would probably have the effect that nobody outside of IBM would do any significant build testing on that architecture. > I would even be happy to make it such that SBUS drivers can be > enabled for test building on x86, and in fact right now in > Linus's tree that's very close to doable. I have no objection to that. I have MIPS to burn on my x86 boxes. s390 MIPS cost a few orders of magnitude more. -- Chris