From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759791AbcIWNSf (ORCPT ); Fri, 23 Sep 2016 09:18:35 -0400 Received: from foss.arm.com ([217.140.101.70]:59178 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758864AbcIWNSe (ORCPT ); Fri, 23 Sep 2016 09:18:34 -0400 Subject: Re: [PATCH 1/2] armv8: aarch32: Execute 32-bit Linux for LayerScape platforms To: Stuart Yoder , Alison Wang , "shawnguo@kernel.org" , "kernel@pengutronix.de" , Fabio Estevam Estevam , "linux@armlinux.org.uk" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Scott Wood , Leo Li References: <1474597146-33312-1-git-send-email-b18965@freescale.com> Cc: Jason Jin From: Robin Murphy Message-ID: Date: Fri, 23 Sep 2016 14:18:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/09/16 14:13, Stuart Yoder wrote: > > >> -----Original Message----- >> From: Robin Murphy [mailto:robin.murphy@arm.com] >> Sent: Friday, September 23, 2016 7:17 AM >> To: Alison Wang ; shawnguo@kernel.org; kernel@pengutronix.de; Fabio Estevam >> Estevam ; linux@armlinux.org.uk; linux-arm-kernel@lists.infradead.org; linux- >> kernel@vger.kernel.org; Scott Wood ; Stuart Yoder ; Leo Li >> >> Cc: Jason Jin >> Subject: Re: [PATCH 1/2] armv8: aarch32: Execute 32-bit Linux for LayerScape platforms >> >> Hi Alison, >> >> On 23/09/16 03:19, Alison Wang wrote: >>> The ARMv8 architecture supports: >>> 1. 64-bit execution state, AArch64. >>> 2. 32-bit execution state, AArch32, that is compatible with previous >>> versions of the ARM architecture. >>> >>> LayerScape platforms are compliant with ARMv8 architecture. This patch >>> is to support running 32-bit Linux kernel for LayerScape platforms. >>> >>> Verified on LayerScape LS1043ARDB, LS1012ARDB, LS1046ARDB boards. >>> >>> Signed-off-by: Ebony Zhu >>> Signed-off-by: Alison Wang >>> --- >>> arch/arm/Kconfig | 9 +++++++++ >>> arch/arm/mach-imx/Kconfig | 14 ++++++++++++++ >>> arch/arm/mach-imx/Makefile | 4 +++- >>> arch/arm/mach-imx/mach-layerscape.c | 23 +++++++++++++++++++++++ >>> 4 files changed, 49 insertions(+), 1 deletion(-) >>> create mode 100644 arch/arm/mach-imx/mach-layerscape.c >>> >>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig >>> index f0c8068..e8d470e 100644 >>> --- a/arch/arm/Kconfig >>> +++ b/arch/arm/Kconfig >>> @@ -294,6 +294,15 @@ config PGTABLE_LEVELS >>> default 3 if ARM_LPAE >>> default 2 >>> >>> +config ARCH_AARCH32_ES_SUPPORT >>> + def_bool n >>> + help >>> + The ARMv8 architecture supports 64-bit execution state, AArch64 >>> + and 32-bit execution state, AArch32, that is compatible with >>> + previous versions of the ARM architecture. >>> + >>> + Enable AArch32 execution state support for ARMv8 architecture. >> >> What's this supposed to do, exactly? I've been running 32-bit kernels on >> my Juno with very little issue (beyond a couple of DT tweaks, and some >> firmware hacks with a corresponding bit of A64 assembly tacked on the >> front of the zImage to switch into AArch32 state). > > Which arch/arm/mach-* platform are you using for Juno? I don't even know! :) I just start with a multi_v7_defconfig plus a few extra bits (LPAE, KVM, sil24, sky2, etc.) and it works. I guess it's the combination of mach-vexpress and mach-virt. Robin. > > Thanks, > Stuart >