From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52322) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUwFA-0007f1-SL for qemu-devel@nongnu.org; Thu, 27 Aug 2015 08:25:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZUwF7-00032X-P3 for qemu-devel@nongnu.org; Thu, 27 Aug 2015 08:25:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46584) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZUwF7-000320-L0 for qemu-devel@nongnu.org; Thu, 27 Aug 2015 08:25:21 -0400 Date: Thu, 27 Aug 2015 15:25:17 +0300 From: "Michael S. Tsirkin" Message-ID: <20150827152348-mutt-send-email-mst@redhat.com> References: <20150826165140.6bab7d28@bahia.local> <55DE970B.6040807@redhat.com> <20150827135126-mutt-send-email-mst@redhat.com> <20150827140715-mutt-send-email-mst@redhat.com> <20150827151601-mutt-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH 1/2] memory: allow zero size for adjust_endianness() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Paolo Bonzini , Jason Wang , QEMU Developers , Greg Kurz On Thu, Aug 27, 2015 at 01:20:52PM +0100, Peter Maydell wrote: > On 27 August 2015 at 13:17, Michael S. Tsirkin wrote: > > Basically the point is that ABI is extended to make > > ioeventfd with len = 0 mean "any length". > > 0 is thus not meaningless anymore. > > But how can you do adjustment for incorrect endianness > if you don't know the size of the data that you're > trying to work with? That's why this switch insists > that the size is 1, 2, 4 or 8. > > -- PMM For kvm at least, "any length" implies "any data". So data is eventually discarded, we don't really need to adjust it for endian-ness. -- MST