From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 0/3] virtio-mmio: handle BE guests on LE hosts Date: Mon, 14 Oct 2013 16:56:34 +0200 Message-ID: <525C0622.8040504@redhat.com> References: <1381502171-8187-1-git-send-email-marc.zyngier@arm.com> <525BEBB4.4050603@redhat.com> <525BF089.9050408@arm.com> <2CDDB541-0E92-4452-831E-0B29B24A7C89@suse.de> <525BF656.7020207@arm.com> <20131014140527.GB5106@redhat.com> <525BFBF9.5010804@arm.com> <8C68DB9E-8391-4CF2-BB82-A49BDA26998B@suse.de> <525C0514.5030103@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Alexander Graf , "Michael S. Tsirkin" , "kvm@vger.kernel.org mailing list" , Pawel Moll , "kvmarm@lists.cs.columbia.edu" , linux-arm-kernel To: Marc Zyngier Return-path: Received: from mx1.redhat.com ([209.132.183.28]:57510 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754841Ab3JNO5O (ORCPT ); Mon, 14 Oct 2013 10:57:14 -0400 In-Reply-To: <525C0514.5030103@arm.com> Sender: kvm-owner@vger.kernel.org List-ID: Il 14/10/2013 16:52, Marc Zyngier ha scritto: > > > Sure. And I imagine this traps back into the kernel to read some > > > register and find out what the endianness of the accessing CPU is? > > > > Not yet. To be exact, it does the below today. But all virtio device > > emulation is 100% guest endianness unaware. This helper is the only > > piece of code where it gets any idea what endianness the guest has. So > > by checking for references to it in the code you know where endianness > > is an issue. And that's only in the config space. > > Only config space? How do you deal with virtio ring descriptors, for > example? They also use guest endianness, but do not use virtio_is_big_endian() (yet?) so Alex missed them. Paolo