Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753202Ab3IXDtS (ORCPT ); Mon, 23 Sep 2013 23:49:18 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:19512 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752216Ab3IXDtR (ORCPT ); Mon, 23 Sep 2013 23:49:17 -0400 Message-ID: <52410B49.3050306@huawei.com> Date: Tue, 24 Sep 2013 11:47:21 +0800 From: Yijing Wang User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Alexey Neyman CC: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Bjorn Helgaas , "Rafael J. Wysocki" , Feng Tang , , Subject: Re: [PATCH] Fix coalescing host bridge windows in arch/x86/pci/acpi.c References: <6362938.J7ZtNEOFpc@mistral> In-Reply-To: <6362938.J7ZtNEOFpc@mistral> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.135.76.69] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1873 Lines: 47 On 2013/9/23 14:15, Alexey Neyman wrote: > [Resending due to no response to the original message in a week] > > Hi all, > > I have a board with a BIOS bug that reports the following I/O port regions in > _CRS on one of the host bridges: > > 0x0000-0x03af // #0 > 0x03e0-0x0cf7 // #1 > 0x03b0-0x03bb // #2 > 0x03c0-0x03df // #3 > 0x0000-0xdfff // #4 > 0xf000-0xffff // #5 > > Obviously, region number #4 is erroneous as it overlaps with regions #0..3. > The code in coalesce_windows() in arch/x86/pci/acpi.c attempts to recover from > such kind of BIOS bugs by merging the overlapping regions. Current code > expands region #0 to 0x0000-0xdffff and makes region #4 ignored. As a result, > overlap of the expanded region #0 with regions #1..3 remains undetected (as > the inner loop already compared them with region #0). As a result, regions > #1..3 are inserted into the resource tree even though they overlap with > adjusted region #0 - which later results in resource conflicts for PCI devices > with IO ports in one of those regions (e.g., for an PCI IDE controller in > legacy mode - which has port 0x3f6). The kernel then refuses to initialize > these devices. > > The fix: instead of expanding res1 and ignoring res2, do the opposite. The > res2 window is yet to be compared against all windows between res1 and res2 > (regions #1..3 in the above example), so the resulting resource map will > include just the expanded region - and will ignore any overlapping ones. > > Signed-off-by: Alexey Neyman > It looks fine to me, but I have no platform to test it. :) -- Thanks! Yijing -- 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/