From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pandora.armlinux.org.uk ([78.32.30.218]:44764 "EHLO pandora.armlinux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754324AbeFVRKI (ORCPT ); Fri, 22 Jun 2018 13:10:08 -0400 Date: Fri, 22 Jun 2018 18:09:51 +0100 From: Russell King - ARM Linux Subject: Re: [PATCHv4 4/4] ARM: versatile: support configuring versatile machine for no-MMU Message-ID: <20180622170951.GY17671@n2100.armlinux.org.uk> References: <20180622110145.GU17671@n2100.armlinux.org.uk> <20180622161101.GW17671@n2100.armlinux.org.uk> <20180622164012.GX17671@n2100.armlinux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Nicolas Pitre Cc: Geert Uytterhoeven , Greg Ungerer , Linux ARM , Vladimir Murzin , Chris Brandt , Arnd Bergmann , linux-kbuild On Fri, Jun 22, 2018 at 12:54:18PM -0400, Nicolas Pitre wrote: > On Fri, 22 Jun 2018, Russell King - ARM Linux wrote: > > > On Fri, Jun 22, 2018 at 12:21:33PM -0400, Nicolas Pitre wrote: > > > On Fri, 22 Jun 2018, Russell King - ARM Linux wrote: > > > > That is actually incorrect - you're too used to the dynamic fixup of > > > > virt_to_phys() and friends now! > > > > > > > > Given that XIP is typically used in environments where the kernel text > > > > is very much unmodifyable, we disable CONFIG_ARM_PATCH_PHYS_VIRT. When > > > > disabled, we use a constant translation, based upon the build-time > > > > CONFIG_PHYS_OFFSET and CONFIG_PAGE_OFFSET settings. > > > > > > > > The early assembler relies upon these settings - which must be known > > > > before we enable the MMU. As such, DT parsing is not available to us > > > > at that point (as we can't run any C code, because we won't be calling > > > > it at the address it was linked for.) > > > > > > I think you got me wrong. I meant DT parsing at config or build time, > > > not at run time. > > > > That seems backwards and complicated. It seems this would end up > > with: > > > > - you configure the kernel > > - build the dtb files > > - reconfigure parsing a specific dtb file built in the previous step > > - build the kernel proper > > ... or just stick the right value manually when prompting for > XIP_PHYS_ADDR. Really, depending on DT is a non issue that only pulls > the conversation away from the actual kconfig language limitation that > needs to be overcome. Which is _exactly_ what we do today, so I don't see what point you're making in this sub-thread. I thought we were discussing about getting Kconfig to obtain settings from dtb files. If you have a point to make, please don't make the discussion impossible by changing your point, it makes it a waste of time trying to have a discussion. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 8.8Mbps down 630kbps up According to speedtest.net: 8.21Mbps down 510kbps up