From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44375) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UyjL6-0002Qm-Ne for qemu-devel@nongnu.org; Mon, 15 Jul 2013 10:01:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UyjL4-0005nZ-5j for qemu-devel@nongnu.org; Mon, 15 Jul 2013 10:01:20 -0400 Received: from mail-ie0-f174.google.com ([209.85.223.174]:54965) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UyjL4-0005ml-07 for qemu-devel@nongnu.org; Mon, 15 Jul 2013 10:01:18 -0400 Received: by mail-ie0-f174.google.com with SMTP id 9so25901539iec.33 for ; Mon, 15 Jul 2013 07:01:16 -0700 (PDT) From: Anthony Liguori In-Reply-To: References: <51C75FA6.6080903@reactos.org> <51C7E21A.9090005@web.de> <8A36D64D-0625-49E1-9E59-391DAEEBD1FC@suse.de> <51DEA91B.40903@suse.de> <3FAA7DE1-06A0-45C5-885C-0433BCC0CFE8@suse.de> <5D205309-1154-4730-902E-BF07F5D3B4EB@suse.de> <1373581960.19894.109.camel@pasglop> <02433CA4-954D-4C56-A4A4-7BC0D62638C0@suse.de> <1373628932.19894.158.camel@pasglop> <878v1bvfaw.fsf@codemonkey.ws> <1373669427.19894.202.camel@pasglop> Date: Mon, 15 Jul 2013 09:01:13 -0500 Message-ID: <87sizfudli.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH v3 11/14] ioport: Switch dispatching to memory core layer List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell , Benjamin Herrenschmidt Cc: Liu Ping Fan , Alexander Graf , qemu-devel Developers , "qemu-ppc@nongnu.org list:PowerPC" , Paolo Bonzini , Jan Kiszka , Andreas =?utf-8?Q?F=C3=A4rber?= , =?utf-8?Q?Herv=C3=A9?= Poussineau Peter Maydell writes: > On 12 July 2013 23:50, Benjamin Herrenschmidt wrote: >> Our experience is that it actually works fine for almost everything >> except virtio :-) ie mostly TARGET_WORDS_BIGENDIAN is irrelevant (and >> should be). > > I agree that TARGET_WORDS_BIGENDIAN *should* go away, but > it exists currently. Do you actually implement a CPU which > does dynamic endianness flipping? TCG already supports bi-endianness for PPC. Grep for 'le_mode' in target-ppc/translate.c to see how the TCG instruction stream is affected by it. On PPC, le_mode only really affects load/stores and instruction decoding. Any shared data structures between the CPU and OS remain big endian. So TARGET_WORDS_BIGENDIAN is still accurate even when le_mode=1. It's not the semantic equivalent of changing TARGET_WORDS. Regards, Anthony Liguori > Is it at all efficient > in the config which is the opposite of whatever > TARGET_WORDS_BIGENDIAN says? > > thanks > -- PMM