From mboxrd@z Thu Jan 1 00:00:00 1970 From: Santosh Shilimkar Subject: Re: [PATCH] ARM: decompressor: Fix mmu mapping for non-DRAM address space. Date: Thu, 10 May 2012 12:41:35 +0530 Message-ID: <4FAB6A27.3050509@ti.com> References: <1336398149-26153-1-git-send-email-santosh.shilimkar@ti.com> <20120508124116.GE17798@arm.com> <20120508215554.GA18980@n2100.arm.linux.org.uk> <20120509122348.GA30632@n2100.arm.linux.org.uk> <20120509154849.GA10375@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from na3sys009aog131.obsmtp.com ([74.125.149.247]:53406 "EHLO na3sys009aog131.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756660Ab2EJHLn (ORCPT ); Thu, 10 May 2012 03:11:43 -0400 Received: by obceq6 with SMTP id eq6so1672660obc.9 for ; Thu, 10 May 2012 00:11:41 -0700 (PDT) In-Reply-To: <20120509154849.GA10375@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: Catalin Marinas , "linux-arm-kernel@lists.infradead.org" , "linux-omap@vger.kernel.org" , R Sricharan On Wednesday 09 May 2012 09:18 PM, Russell King - ARM Linux wrote: > On Wed, May 09, 2012 at 06:00:10PM +0530, Shilimkar, Santosh wrote: >> On Wed, May 9, 2012 at 5:53 PM, Russell King - ARM Linux >> wrote: >>> On Wed, May 09, 2012 at 02:20:28PM +0530, Shilimkar, Santosh wrote: >>>> The only change done common code is clearing 'XN' bit for DRAM >>>> region in page table entries. The other change of setting the DACR >>>> register is done in ARMv7 specific code. >>> >>> Yes, XN is an ARMv6+ thing. Before ARMv5, it was implementation defined. >>> >>> Some implementations used the bit to mean "allow writes to update the >>> cache". Other implementations labelled this bit as "should be zero" >>> while others labelled it as "should be one". >>> >> Good to know. >> >>> The upshot of this is, we know that having this bit as '1' means that >>> all the CPUs we support today work. I would be _very_ concerned to >>> change this bit to zero as we _really_ don't know how the pre-ARMv6 >>> CPUs would react. >>> >> I agree. >> >>> The solution to this is pretty simple - if ARMv6+ needs a different >>> base section mapping value, then we need to extract that from the code >>> and pass in the base section mapping value. >>> >>> I'll sort out a patch later today for this. >> Great. > > This works for my 4430SDP board. I haven't booted it on anything else yet. > Please can you check that this solves the issue for you? Thanks. > Yes it does. Are you planning to merge below patch as is or split the patch like 1) Refactoring 2) ARMv7 fix Either is fine with me. Acked-by: Santosh Shilimkar Regards Santosh