From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.genesi-usa.com (mithrandir.softwarenexus.net [66.98.186.96]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id DED68DE05E for ; Sat, 2 Jun 2007 02:35:17 +1000 (EST) Message-ID: <46604AE0.5040700@genesi-usa.com> Date: Fri, 01 Jun 2007 17:35:44 +0100 From: Matt Sealey MIME-Version: 1.0 To: Benjamin Herrenschmidt Subject: Re: [PATCH 3/5] Float the pci bus number on MPC8641HPCN board. References: <11798051102658-git-send-email-wei.zhang@freescale.com> <11798051101543-git-send-email-wei.zhang@freescale.com> <1179805110272-git-send-email-wei.zhang@freescale.com> <1179805110278-git-send-email-wei.zhang@freescale.com> <1179856792.27985.22.camel@rhino> <46B96294322F7D458F9648B60E15112C234A2D@zch01exm26.fsl.freescale.net> <46B96294322F7D458F9648B60E15112C30777C@zch01exm26.fsl.freescale.net> <18015.48278.312517.781244@cargo.ozlabs.ibm.com> <46B96294322F7D458F9648B60E15112C30780F@zch01exm26.fsl.freescale.net> <1180683854.19517.419.camel@localhost.localdomain> In-Reply-To: <1180683854.19517.419.camel@localhost.localdomain> Content-Type: text/plain; charset=UTF-8 Cc: linuxppc-dev@ozlabs.org, Paul Mackerras , Zhang Wei-r63237 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Re enabling proper domain support on 32-bit... now, now, now please! X guys won't merge in code, we've been punished by both sides on Pegasos for nearly 12 months now after there's been a bunch of misguided attempts to 'fix' domain support in X. The real fix is in the kernel to make it very clear that domains and proper, per-domain bus numbering (not global bus numbering) and suchlike is the standard like it is on SPARC and PPC64 and IA64. If ppc32 suddenly goes the way of these, X guys will fix it, there will be patches to work against this kernel, even if they have to detect the kernel version to do it or look at a procfs or sysfs entry to fix up their dumb pci scanning code. I don't think stalling on it "because of X" is right. Fix Linux, X will follow, because it really has to. -- Matt Sealey Genesi, Manager, Developer Relations Benjamin Herrenschmidt wrote: > On Fri, 2007-06-01 at 14:45 +0800, Zhang Wei-r63237 wrote: >> There are lots of lagacy PCI codes in kernel, such as >> pci_bus_to_hose(busnr). If two hose's bus number have overlaps, >> pci_bus_to_hose() can not return the correct hose. And there will >> effect >> /proc/pci and lspci tools. > > More specifically... > > Overlapping bus numbers on separate domains work... on 64 bits :-) The > 32 bits PCI code assumes non-overlapping numbers. The main reason for > that historically was that back then, domains didn't work well. > > The second reasons why I didn't actually fix it is that turning on full > domain support had (and probably still has) the nasty habit of breaking > the X server :-( X is full of most horrible hacks for PCI and it will be > terminally broken until they finally merge the pci-rework branch that > Ian Romanick's been working on for some time now. > > One of these days, one of us will finally tackle merging 32 and 64 bits > PCI code (and fix both of them while at it to better use the generic > code, which involves fixing issues in the said generic code too :-) at > which point I'll enable full domain support for 32 bits as well, with an > option to degrade it to bus number remapping. > > Ben. > > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-dev