From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41080C43219 for ; Thu, 24 Nov 2022 07:22:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229814AbiKXHMi (ORCPT ); Thu, 24 Nov 2022 02:12:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229750AbiKXHM1 (ORCPT ); Thu, 24 Nov 2022 02:12:27 -0500 Received: from loongson.cn (mail.loongson.cn [114.242.206.163]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id D0475CDFFC for ; Wed, 23 Nov 2022 23:14:54 -0800 (PST) Received: from loongson.cn (unknown [112.20.109.110]) by gateway (Coremail) with SMTP id _____8DxM_DZGH9j6XkAAA--.1339S3; Thu, 24 Nov 2022 15:10:17 +0800 (CST) Received: from [192.168.100.127] (unknown [112.20.109.110]) by localhost.localdomain (Coremail) with SMTP id AQAAf8AxiFfXGH9jRUEZAA--.47737S3; Thu, 24 Nov 2022 15:10:16 +0800 (CST) Message-ID: Date: Thu, 24 Nov 2022 15:10:15 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.4.2 Subject: Re: [PATCH v1 1/2] docs/LoongArch: Add boot image header To: Wu XiangCheng Cc: chenhuacai@kernel.org, corbet@lwn.net, alexs@kernel.org, seakeel@gmail.com, kernel@xen0n.name, jiaxun.yang@flygoat.com, linux-doc@vger.kernel.org, loongarch@lists.linux.dev, siyanteng01@gmail.com, Xiaotian Wu , Yun Liu References: <08df007c7488b88ff5400bef6183f9cc68d87616.1669032230.git.siyanteng@loongson.cn> Content-Language: en-US From: Yanteng Si In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID: AQAAf8AxiFfXGH9jRUEZAA--.47737S3 X-CM-SenderInfo: pvl1t0pwhqwqxorr0wxvrqhubq/ X-Coremail-Antispam: 1Uk129KBjvJXoW3Ww15Xr1kuFWxtryUXw4rGrg_yoW7Xw45pr nxJFyxJF1DJryUJr17Jr1UXr1UJr48J3WUGF18try8Jr1jvr1DJr1UJr18XryUGry8AFyU Xw1UJryjyF1UJrDanT9S1TB71UUUUjUqnTZGkaVYY2UrUUUUj1kv1TuYvTs0mT0YCTnIWj qI5I8CrVACY4xI64kE6c02F40Ex7xfYxn0WfASr-VFAUDa7-sFnT9fnUUIcSsGvfJTRUUU bfAYFVCjjxCrM7AC8VAFwI0_Jr0_Gr1l1xkIjI8I6I8E6xAIw20EY4v20xvaj40_Wr0E3s 1l1IIY67AEw4v_Jrv_JF1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxSw2x7M28EF7xv wVC0I7IYx2IY67AKxVWUCVW8JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwA2z4 x0Y4vEx4A2jsIE14v26r4UJVWxJr1l84ACjcxK6I8E87Iv6xkF7I0E14v26r4UJVWxJr1l n4kS14v26r1Y6r17M2AIxVAIcxkEcVAq07x20xvEncxIr21l57IF6xkI12xvs2x26I8E6x ACxx1l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xIIjxv20xvE14v26r126r1DMcIj6I8E 87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lc7I2V7IY0V AS07AlzVAYIcxG8wCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwCFI7km 07C267AKxVWUXVWUAwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r 1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWU JVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr1lIxAIcVCF04k26cxKx2IYs7xG6r 1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Jr0_GrUv cSsGvfC2KfnxnUUI43ZEXa7IU8q2NtUUUUU== Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On 11/22/22 00:58, Wu XiangCheng wrote: > +Cc: Yun Liu > > 2022-11-21 (一) 20:16:30 +0800 Yanteng Si 曰： >> Describes the meaning and value of the image header field. >> >> Suggested-by: Xiaotian Wu >> Signed-off-by: Yanteng Si >> --- >> Documentation/loongarch/boot-image-header.rst | 76 +++++++++++++++++++ >> Documentation/loongarch/index.rst | 1 + >> 2 files changed, 77 insertions(+) >> create mode 100644 Documentation/loongarch/boot-image-header.rst >> >> diff --git a/Documentation/loongarch/boot-image-header.rst b/Documentation/loongarch/boot-image-header.rst >> new file mode 100644 >> index 000000000000..92a953a6f2e6 >> --- /dev/null >> +++ b/Documentation/loongarch/boot-image-header.rst >> @@ -0,0 +1,76 @@ >> +.. SPDX-License-Identifier: GPL-2.0 >> + >> +==================================== >> +Boot image header in LoongArch Linux >> +==================================== >> + >> +:Author: Yanteng Si >> +:Date: 18 Nov 2022 >> + >> +This document only describes the boot image header details for >> +LoongArch Linux. >> + >> +The following 64-byte header is present in decompressed Linux >> +kernel image:: >> + >> + u32 MZ_MAGIC /* "MZ", MS-DOS header */ >> + u32 res0 = 0 /* reserved */ >> + u64 kernel_entry /* Kernel entry point */ >> + u64 _end - _text /* Kernel image effective size */ >> + u64 0 /* Kernel image load offset from start of RAM */ >> + u64 res1 = 0 /* reserved */ >> + u64 res2 = 0 /* reserved */ >> + u64 res3 = 0 /* reserved */ >> + u32 res4 = 0 /* reserved */ >> + u32 pe_header - _head /* Offset to the PE header */ >> + > Any code related need to be linked here? The related code is in line 22 of the arch/loongarch/kernel/head.S, which is not very readable. > >> + >> +Header notes >> +============ >> + >> +Currently, LoongArch has removed the "magic" field. >> + >> +According to the EFI specification, the PE/COFF image file header is >> +required at the beginning of the kernel image; the LoongArch kernel >> +supports the EFI stub, so the first two bytes of the kernel image header >> +are "MZ" magic characters, and 0x3c should point to the rest of the >> +PE/COFF file header, between which The kernel entry point, image >> +effectivesize, and image load offset layout are as follows:: >> + >> + +-----------------------------------------------+ >> + 0x0: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | >> + +-----------------------------------------------+ >> + 0x8: | MZ_MAGIC | res0 | >> + +-----------------------------------------------+ >> + 0x10: | kernel_entry | >> + +-----------------------------------------------+ >> + 0x18: | _end - _text | >> + +-----------------------------------------------+ >> + 0x20: | 0 | >> + +-----------------------------------------------+ >> + 0x28: | res1 | >> + +-----------------------------------------------+ >> + 0x30: | res2 | >> + +-----------------------------------------------+ >> + 0x38: | res3 | >> + +-----------------------------------------------+ >> + 0x40: | res14 | PE header | >> + +-----------------------------------------------+ >> + > emmm, this figure... > > So MZ_MAGIC start from 0x08 ? Form 0x00. > > Or > > 0 1 2 3 4 5 6 7 > +-----------------------+-----------------------+ > 0x00 | MZ_MAGIC | res0 | > +-----------------------+-----------------------+ > 0x08 | kernel_entry | > +-----------------------------------------------+ > 0x10 | _end - _text | > +-----------------------------------------------+ > 0x18 | 0 | > +-----------------------------------------------+ > 0x20 | res1 | > +-----------------------------------------------+ > 0x28 | res2 | > +-----------------------------------------------+ > 0x30 | res3 | > +-----------------------+-----------------------+ > 0x38 | res14 | PE header | > +-----------------------+-----------------------+ Great! In patch V2: res14 -> res4, I don't know why, I misspelled. Thanks, Yanteng > > If the figure is too difficult to draw, a simple table can also be used > to instead. > > Offset Name Size Note > ... > >> + >> +All bit fields are in little endian: >> + >> + - MZ: Effective length of 2 bytes; >> + >> + - kernel entry point: leaving 6 bytes blank in front, starting >> + from 0x8, with a effective length of 8 bytes; >> + >> + - kernel image effective size: Immediately following the kernel >> + entry point, with a effective length of 8 bytes, this field is >> + required for the bootloader; >> + >> + - kernel image load offset: Immediately following the kernel >> + image effective size, with a effective length of 8 bytes; >> + >> + - Offset to the PE header: leaving 28 bytes blank in front, >> + starting from 0x3c, with a effective length of 4 bytes. >> diff --git a/Documentation/loongarch/index.rst b/Documentation/loongarch/index.rst >> index aaba648db907..97419821adf9 100644 >> --- a/Documentation/loongarch/index.rst >> +++ b/Documentation/loongarch/index.rst >> @@ -10,6 +10,7 @@ LoongArch Architecture >> >> introduction >> irq-chip-model >> + boot-image-header >> >> features >> >> -- >> 2.31.1 >>