Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932749Ab2EPCLg (ORCPT ); Tue, 15 May 2012 22:11:36 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:45140 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758387Ab2EPCLe convert rfc822-to-8bit (ORCPT ); Tue, 15 May 2012 22:11:34 -0400 MIME-Version: 1.0 In-Reply-To: <20120516011833.GA6599@richard> References: <20120410090306.GA7056@richard> <20120422155202.GA13540@richard> <4F95B17B.3030401@redhat.com> <20120514015536.GA3331@richard> <20120514064615.GB26605@richard> <20120516011833.GA6599@richard> Date: Tue, 15 May 2012 19:11:34 -0700 X-Google-Sender-Auth: 4gC8BmF6Qr1rvFVTvpM1RJyjef8 Message-ID: Subject: Re: One problem in reassign pci bus number? From: Yinghai Lu To: Richard Yang Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2838 Lines: 68 On Tue, May 15, 2012 at 6:18 PM, Richard Yang wrote: > On Tue, May 15, 2012 at 10:32:46AM -0700, Yinghai Lu wrote: >>>>>>On 04/22/2012 11:52 AM, Richard Yang wrote: >>>>>>>All, >>>>>>> >>>>>>>I am reading the pci_scan_bridge() and not sure what will happen in >>>>>>>following situation. >>>>>>> >>>>>>>Suppose the kernel is not passed the pci=assign-busses. >>>>>>> >>>>>>>Below is a picture about the pci system. >>>>>>> >>>>>>> ? ? ? ? ? ? ? ? ? ?+-------+ >>>>>>> ? ? ? ? ? ? ? ? ? ?| ? ? ? | root bridge(0,255) >>>>>>> ? ? ? ? ? ? ? ? ? ?+---+---+ >>>>>>> ? ? ? ? ? ? ? ? ? ? ? ?| ? ? ? ? ?Bus 0 >>>>>>> ? ? ? -----+-----------+------------------------------+-- >>>>>>> ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| >>>>>>> ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| >>>>>>> ? ? ? ? ? ?| ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| >>>>>>> ? ? ? +----+----+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? +-----+-----+ >>>>>>> ? ? ? | ? ? ? ? | ?B1(1,15) ? ? ? ? ? ? ? ? ? ? | ? ? ? ? ? |B2(16,28) >>>>>>> ? ? ? +----+----+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? +-----+-----+ >>>>>>> ? ? ? ? ? ?| ?Bus 1 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?Bus 16 >>>>>>> ? ? ? -----+----------------------- ? ? ? ? ----------+---------------- >>>>>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? | >>>>>>> ? ? ? ? ? ? ? ? ? ? ? ?+----+----+ >>>>>>> ? ? ? ? ? ? ? ? ? ? ? ?| ? ? ? ? | B3 >>>>>>> ? ? ? ? ? ? ? ? ? ? ? ?+---------+ >>>>>>> >>>>>>>Suppose B1 and B2 works fine with the BIOS, which get the right bus >>>>>>>number and range. >>>>>>> >>>>>>>B3 does not works fine with the BIOS, which doesn't get the bus number. >>>>>>> >>>>> Take my original question. >>>>> >>>>> B3 doesn't get the bus number, which its parent doesn't have free bus >>>>> number and there is no gap between B1 and B2. >>>>> >>>>> So in this case, the probe_resource() can't find bus number for B3. >>>>> Then cause pci_bridge_probe_busn_res() return non-zero. >>>>> >>>>> Then B3 couldn't work fine? >>>> >>>>B3 is on Bus 1? B3 is the one of bridges on Bus1? >>> No, ?I omit other bridges on Bus#1. >>> They will occupy bus number 2-15, which is calculated by BIOS and set to >>> bridge's configuration space. >> >>with that new condition, probe_resource will return zero. >> >>for those kind of case: >>1. use echo 1 > /sys .../remove to remove devices under Bridge2. >>2. use setpci to change bus register of bridge2 to move high to make >>more space for bridge 1. >>3. rescan bridge 1 and bridge 2. > So these steps is done after boot up and user find B3 doesn't work? yes, after os is booted up. Yinghai -- 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/