From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 0/4] Hacks to allow booting ARM SMP kernel on UP ARMv7 Date: Tue, 17 Aug 2010 17:12:11 +0300 Message-ID: <20100817141210.GJ12184@atomide.com> References: <20100817104414.19061.38999.stgit@baageli.muru.com> <20100817135205.GC20325@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-02-ewr.mailhop.org ([204.13.248.72]:64632 "EHLO mho-02-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753635Ab0HQOMU (ORCPT ); Tue, 17 Aug 2010 10:12:20 -0400 Content-Disposition: inline In-Reply-To: <20100817135205.GC20325@n2100.arm.linux.org.uk> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Russell King - ARM Linux Cc: linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, bryan.wu@canonical.com * Russell King - ARM Linux [100817 16:44]: > On Tue, Aug 17, 2010 at 01:53:12PM +0300, Tony Lindgren wrote: > > Here are some experimental patches to allow booting ARMv7 SMP > > kernel on UP to some extent. Posting these early in case it is > > of any help as I know at least Bryan Wu is working on similar > > issues. > > I think these are compeltely the wrong direction. First thing to realise > is that XIP in the "SMP and UP in one kernel" is not really practical - > I'm not sure that many people who want that kind of flexibility also want > XIP too. > > So let's forget about the kernel text being read-only. OK, at least for me. > The second thing to realise is that most of the SMP dependencies are in > assembly - and we can make lists of instructions and their modified > versions that would be necessary to boot a SMP kernel on UP. OK cool. > So something like this will do (though note that not everywhere has been > fixed up - such as the page table flags - or this patch tested yet.) Great, will give it a try hopefully tomorrow. Sounds like that's the way to deal with fixing up things when booting up older UP ARMv6 without the 32v6 support :) > If we don't want the SMP-on-UP support for SMP kernels (it's not actually > all that big - around 512 bytes) then we can discard the .smpalt.init > section and the __fixup_smp code. OK Regards, Tony