Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753736AbaFXVzF (ORCPT ); Tue, 24 Jun 2014 17:55:05 -0400 Received: from gate.crashing.org ([63.228.1.57]:56483 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750925AbaFXVzD (ORCPT ); Tue, 24 Jun 2014 17:55:03 -0400 Message-ID: <1403646877.4587.184.camel@pasglop> Subject: Re: [PATCH] vfio: Fix endianness handling for emulated BARs From: Benjamin Herrenschmidt To: Alexey Kardashevskiy Cc: Alex Williamson , Alexander Graf , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Nikunj A Dadhania Date: Wed, 25 Jun 2014 07:54:37 +1000 In-Reply-To: <53A98C38.8020205@ozlabs.ru> References: <1403091391-31780-1-git-send-email-aik@ozlabs.ru> <1403116512.3707.175.camel@ul30vt.home> <53A233E9.6030006@ozlabs.ru> <53A241F6.9010307@ozlabs.ru> <53A25D74.5000804@ozlabs.ru> <1403234514.3707.278.camel@ul30vt.home> <1403305961.4587.66.camel@pasglop> <53A94EBD.101@ozlabs.ru> <53A955F5.6050801@suse.de> <53A9741B.1040500@ozlabs.ru> <53A97486.4070604@suse.de> <53A976B7.3070709@ozlabs.ru> <53A97BA9.4020702@suse.de> <1403619685.16078.15.camel@ul30vt.home> <53A98C38.8020205@ozlabs.ru> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.2 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-06-25 at 00:33 +1000, Alexey Kardashevskiy wrote: > > I do not understand why @val is considered LE here and need to be > converted > to CPU. Really. I truly believe it should be cpu_to_le32(). No. Both are slightly wrong semantically but le32_to_cpu() is less wrong :-) iowrite32 supposedly takes a "cpu" value as argument and writes an "le" value. So if anything, you need something that converts to a "cpu" value before you call iowrite32. Now it's still slightly wrong because the "input" to le32_to_cpu() is supposed to be an "LE" value but of course here it's not, it's a "cpu" value too :-) But yes, I agree with aw here, either do nothing or stick a set of iowriteXX_native or something equivalent in the generic iomap header, define them in term of iowrite32be/iowrite32 based on the compile time endian of the arch. Hitting asm-generic/iomap.h I think will cover all archs except ARM. For ARM, just hack arch/arm/asm/io.h Cheers, Ben. -- 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/