From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751597AbcFXOIT (ORCPT ); Fri, 24 Jun 2016 10:08:19 -0400 Received: from mail-vk0-f67.google.com ([209.85.213.67]:34137 "EHLO mail-vk0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbcFXOIS (ORCPT ); Fri, 24 Jun 2016 10:08:18 -0400 Subject: Re: [Xen-devel] [PATCH v3 1/2] xen-pciback: return proper values during BAR sizing To: Jan Beulich , David Vrabel , Boris Ostrovsky , Konrad Rzeszutek Wilk , Juergen Gross References: <5756857802000078000F268D@prv-mh.provo.novell.com> <5756864102000078000F269A@prv-mh.provo.novell.com> <576D15DE02000078000F8678@prv-mh.provo.novell.com> Cc: xen-devel , linux-kernel@vger.kernel.org From: David Vrabel Message-ID: <576D3ECE.3030001@cantab.net> Date: Fri, 24 Jun 2016 15:08:14 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.5.0 MIME-Version: 1.0 In-Reply-To: <576D15DE02000078000F8678@prv-mh.provo.novell.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/06/16 10:13, Jan Beulich wrote: > Reads following writes with all address bits set to 1 should return all > changeable address bits as one, not the BAR size (nor, as was the case > for the upper half of 64-bit BARs, the high half of the region's end > address). Presumably this didn't cause any problems so far because > consumers use the value to calculate the size (usually via val & -val), > and do nothing else with it. > > But also consider the exception here: Unimplemented BARs should always > return all zeroes. > > And finally, the check for whether to return the sizing address on read > for the ROM BAR should ignore all non-address bits, not just the ROM > Enable one. Applied to for-linus-4.7b, thanks. David