From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752488AbbJOJTW (ORCPT ); Thu, 15 Oct 2015 05:19:22 -0400 Received: from eu-smtp-delivery-143.mimecast.com ([146.101.78.143]:42438 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751452AbbJOJTQ convert rfc822-to-8bit (ORCPT ); Thu, 15 Oct 2015 05:19:16 -0400 Subject: Re: [PATCHv3 09/11] arm64: Add page size to the kernel image header To: Mark Rutland References: <1444821634-1689-1-git-send-email-suzuki.poulose@arm.com> <1444821634-1689-10-git-send-email-suzuki.poulose@arm.com> <20151014172756.GJ5041@leverpostej> Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will.deacon@arm.com, steve.capper@linaro.org, marc.zyngier@arm.com, ard.biesheuvel@linaro.org, christoffer.dall@linaro.org From: "Suzuki K. Poulose" Message-ID: <561F6F91.2010707@arm.com> Date: Thu, 15 Oct 2015 10:19:13 +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: <20151014172756.GJ5041@leverpostej> X-OriginalArrivalTime: 15 Oct 2015 09:19:13.0500 (UTC) FILETIME=[8EB989C0:01D1072A] X-MC-Unique: fSYRzY-vR1SMqx2-DVcwIg-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 14/10/15 18:27, Mark Rutland wrote: > On Wed, Oct 14, 2015 at 12:20:32PM +0100, Suzuki K. Poulose wrote: >> From: Ard Biesheuvel >> >> This patch adds the page size to the arm64 kernel image header >> so that one can infer the PAGESIZE used by the kernel. This will >> be helpful to diagnose failures to boot the kernel with page size >> not supported by the CPU. >> >> Signed-off-by: Ard Biesheuvel >> Signed-off-by: Suzuki K. Poulose >> Acked-by: Catalin Marinas >> Reviewed-by: Christoffer Dall >> --- >> Documentation/arm64/booting.txt | 7 ++++++- >> arch/arm64/kernel/image.h | 5 ++++- >> 2 files changed, 10 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt >> index 7d9d3c2..aaf6d77 100644 >> --- a/Documentation/arm64/booting.txt >> +++ b/Documentation/arm64/booting.txt >> @@ -104,7 +104,12 @@ Header notes: >> - The flags field (introduced in v3.17) is a little-endian 64-bit field >> composed as follows: >> Bit 0: Kernel endianness. 1 if BE, 0 if LE. >> - Bits 1-63: Reserved. >> + Bit 1-2: Kernel Page size. >> + 0 - Unspecified. >> + 1 - 4K >> + 2 - 16K >> + 3 - 64K >> + Bits 3-63: Reserved. >> >> - When image_size is zero, a bootloader should attempt to keep as much >> memory as possible free for use by the kernel immediately after the >> diff --git a/arch/arm64/kernel/image.h b/arch/arm64/kernel/image.h >> index 6eb8fee..e45759e 100644 >> --- a/arch/arm64/kernel/image.h >> +++ b/arch/arm64/kernel/image.h >> @@ -47,7 +47,10 @@ >> #define __HEAD_FLAG_BE 0 >> #endif >> >> -#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) >> +#define __HEAD_FLAG_PAGE_SIZE ((PAGE_SHIFT - 10) / 2) >> + >> +#define __HEAD_FLAGS (__HEAD_FLAG_BE << 0) | \ >> + (__HEAD_FLAG_PAGE_SIZE << 1) > > I'd prefer that we also had brackets around the whole of the > __HEAD_FLAGS value, so we don't get caught out later on by some > unexpected expansion (though we are safe currently). > Sure, will add that. > With that: > > Acked-by: Mark Rutland Thanks Suzuki