From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753306AbbJOPCj (ORCPT ); Thu, 15 Oct 2015 11:02:39 -0400 Received: from eu-smtp-delivery-143.mimecast.com ([146.101.78.143]:16302 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752076AbbJOPCj convert rfc822-to-8bit (ORCPT ); Thu, 15 Oct 2015 11:02:39 -0400 Subject: Re: [PATCHv3 08/11] arm64: Check for selected granule support To: Jeremy Linton , Mark Rutland 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> Cc: 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 From: "Suzuki K. Poulose" Message-ID: <561FC00C.7010003@arm.com> Date: Thu, 15 Oct 2015 16:02:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <561FBC99.9090501@arm.com> X-OriginalArrivalTime: 15 Oct 2015 15:02:36.0397 (UTC) FILETIME=[870221D0:01D1075A] X-MC-Unique: T19jvd-vTRy_7IKQuTX4Bw-1 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15/10/15 15:47, 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. > > 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. > > Of course you will then need a matching stubbed out function for the normal arm kernel as well. OK, I will drop it from this series then and can be worked as a separate patch. Thanks Suzuki