From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753407AbbJOPLU (ORCPT ); Thu, 15 Oct 2015 11:11:20 -0400 Received: from foss.arm.com ([217.140.101.70]:36496 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751834AbbJOPLT (ORCPT ); Thu, 15 Oct 2015 11:11:19 -0400 Date: Thu, 15 Oct 2015 16:11:14 +0100 From: Mark Rutland To: Jeremy Linton Cc: "Suzuki K. Poulose" , linux-arm-kernel@lists.infradead.org, steve.capper@linaro.org, ard.biesheuvel@linaro.org, marc.zyngier@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, christoffer.dall@linaro.org Subject: Re: [PATCHv3 08/11] arm64: Check for selected granule support Message-ID: <20151015151113.GK8825@leverpostej> References: <1444821634-1689-1-git-send-email-suzuki.poulose@arm.com> <1444821634-1689-9-git-send-email-suzuki.poulose@arm.com> <561EC58B.9080408@arm.com> <20151015104515.GE8825@leverpostej> <20151015112532.GA16125@e106634-lin.cambridge.arm.com> <561FBC99.9090501@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <561FBC99.9090501@arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 15, 2015 at 09:47:53AM -0500, Jeremy Linton wrote: > On 10/15/2015 06:25 AM, Suzuki K. Poulose wrote: > >+ /* > >+ * Check to see if the CPU supports the requested pagesize > >+ */ > >+ asm volatile("mrs %0, ID_AA64MMFR0_EL1" : "=r" (aa64mmfr0_el1)); > >+ aa64mmfr0_el1 >>= ID_AA64MMFR0_TGRAN_SHIFT; > >+ if ((aa64mmfr0_el1 & 0xf) != ID_AA64MMFR0_TGRAN_SUPPORTED) { > >+ pr_efi_err(sys_table_arg, PAGE_SIZE_STR" granule not supported by the CPU\n"); > >+ return EFI_UNSUPPORTED; > >+ } > > > This is definitely an improvement over my original hack job. > > I would like to add, that I actually think this should be in a new > function "check_kernel_compatibility" (or whatever) that is called > before handle_kernel_image. To bikeshed, perhaps efi_arch_check_system? > That is because I don't really think it belongs in > handle_kernel_image which is focused on relocation. Plus, if you add > another function, you can avoid the "Failed to relocate kernel" > error that comes out following the granule not supported message. > Further, checks like this in the future will have a place to live. I agree. There are some other diagnostic utilities I'd like to add to the stub (e.g. dumping the memory map and ID registers) that would help with diagnosing boot issues. I started on those at Connect, but realised I needed to first implement half of printf for those to be useful. > Of course you will then need a matching stubbed out function for the > normal arm kernel as well. I'm sure there are similar things we'll want to check for 32-bit (e.g. LPAE support), but a stub should be fine for now. Thanks, Mark.