From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752068Ab0JAW2W (ORCPT ); Fri, 1 Oct 2010 18:28:22 -0400 Received: from gate.crashing.org ([63.228.1.57]:55199 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750902Ab0JAW2V (ORCPT ); Fri, 1 Oct 2010 18:28:21 -0400 Subject: Re: Introduce support for little endian PowerPC From: Benjamin Herrenschmidt To: Olof Johansson Cc: Kumar Gala , linuxppc-dev@lists.ozlabs.org, paulus@samba.org, Ian Munsie , linux-kernel@vger.kernel.org In-Reply-To: <20101001220343.GA10494@lixom.net> References: <1285916771-18033-1-git-send-email-imunsie@au1.ibm.com> <2C5357FA-F87F-457E-B5C1-0DCC5A842DE7@kernel.crashing.org> <1285935283.2463.78.camel@pasglop> <1285966315.2463.141.camel@pasglop> <20101001220343.GA10494@lixom.net> Content-Type: text/plain; charset="UTF-8" Date: Sat, 02 Oct 2010 08:28:02 +1000 Message-ID: <1285972082.2463.250.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-10-01 at 17:03 -0500, Olof Johansson wrote: > > Maybe. Most of it doesn't seem to be that bit-rottable. > > > > The changes to the asm stuff in misc_32.S for example are functions we > > never ever touch once written (libgcc replacements) so I don't see them > > rotting more with LE support than they did with BE :-) > > Does KVM/qemu support running LE guest on BE host? That'd help keeping > the bitrot lower. :) Not yet I suppose :-) But then, I'm not sure it would make a big difference, if you have a 440 board in the first place, you can boot either LE or BE, no need for a special FW or anything. What we've done is basically keep the zImage wrapper BE (for now at least), and have it trampoline to LE when executing the actual kernel (using a cuImage, of course a device-tree enabled u-Boot would probably need something akin to a proper ePAPR zImage to do that but that's reasonably easy to do nowadays). Cheers, Ben.