From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 8 May 2012 10:46:12 +0800 From: Richard Yang To: Yinghai Lu Cc: Richard Yang , Wei Yang , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: One problem in reassign pci bus number? Message-ID: <20120508024612.GA11485@richard> Reply-To: Richard Yang References: <20120504024721.GA6775@richard> <20120504045205.GA21624@richard> <20120506151715.GA7773@richard> <20120507011722.GA8122@richard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: On Sun, May 06, 2012 at 07:04:09PM -0700, Yinghai Lu wrote: >On Sun, May 6, 2012 at 6:17 PM, Richard Yang wrote: >> so this free space will be combined with the free space got from >> parent, form a big space to meet the requirement. >> >> This is the general idea about probe_resource()? >> >> And this is the design decision to find the free space at the end >> of top, even at the start we have more free space? > >no, probe_resource will get from start if space is big enough. > >if not, it will try to extend top. Hmm... for example we still have this parent[70-160] brother1[70-80] res[90-150] brother2[151-160] ->child[105-140] if we call probe_resource(res, new_res, 16, par, 1, 0xff, IORESOURCE_PCI_FIXED); I think this call is used to allocate a res of size 16 under res. When there is no enough free space, it will expend res, and res->parent. While in this situation, res doesn't have enough free space. so it need to expend itself. In the probe_resource() it tries to extend res on the right side. So even there is enough space between brother1 and res, I think the probe_resource() will not return 0. Do you think my analysis is correct? > >Yinghai -- Richard Yang Help you, Help me