From patchwork Fri Jul 19 13:49:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ani Sinha X-Patchwork-Id: 1962504 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=d025E41u; dkim-atps=neutral Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=patchwork.ozlabs.org) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4WQWKx0f0xz1ySl for ; Fri, 19 Jul 2024 23:51:14 +1000 (AEST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sUnzi-00087c-LP; Fri, 19 Jul 2024 09:49:58 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sUnzh-00085w-2i for qemu-devel@nongnu.org; Fri, 19 Jul 2024 09:49:57 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sUnzf-0003Yh-6z for qemu-devel@nongnu.org; Fri, 19 Jul 2024 09:49:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1721396993; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=NzpP5zxi/dF3488FKEyR86bHqqfJr7CcoP3BrHPIZ5Y=; b=d025E41uUutIL5v8L9rlw/VysdX0X/UnEbJrTMV/YjVUGd98RYCxekA8bBIy/JFwl5iFGf QpZU1SS1lrZjqIkhfprIs7YWW2mopuNWlYdsV6lY6nxbegiE8nFppA3fvTQNPg8f9xG16A iUJBvL4vkLSU1rZRixaGa8yUShsT4Pw= Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-54-abTDM1-QOR-tsZHBG4iEqg-1; Fri, 19 Jul 2024 09:49:51 -0400 X-MC-Unique: abTDM1-QOR-tsZHBG4iEqg-1 Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-72c1d0fafb3so1514252a12.2 for ; Fri, 19 Jul 2024 06:49:51 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1721396990; x=1722001790; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=NzpP5zxi/dF3488FKEyR86bHqqfJr7CcoP3BrHPIZ5Y=; b=eLW6cXjoFsdV/tths54aUFKZjAewTmGJxjMuTDkXhRerBZnCDfgFMmzwoMbns/wSi6 eA1iM5P1X7gfC1mj1Ec1pED3XoYS2DDQyJ+n2reAO6BZFyoVNXNJ1OKRRHqyCw1b1Oye s5caqK1qzJPhbWoKYNvutOa9jBtGSowDN+mjF3KxYXNL6BTg+V0jwUmKkhjmCmV8jLgV Mpd130T5/HGgpmUTCJGRQKHokd76vz0edZyss8i+bFgeh0dmIaJeOvfMsf7+sG3ixtMf rpnobPawGDqOm34191dcI3Qyt6Rs4rJGyEOzfdcRmUqAuFBh+3hBd2uBjrALMGcgLlip kRxw== X-Forwarded-Encrypted: i=1; AJvYcCVON/OHs/bTUJ1KoRFrfGNJRbsu46eXY6am/Mfweel8giA43/dX6Vdf1330zJgF/sdEsxsw8DkRN59SuXUT4vOb08bYr8Q= X-Gm-Message-State: AOJu0YwyQ5wm3xDVlhmkXmqVwoHpW5PDrJrLyPo4D6bMA0y5/QESewuc TSDASrWXmr8E2X+f2TyLDE2iRU71Z9+ZT/SZRKt4dIP0JlAIvLEd3RBfUx3PC9S2z8fsJeIbMqc Hjd5RXvVcax9ZSKERBrOMaGiztKlakKCouV2FpPWR1uY7DfEuRzyK X-Received: by 2002:a05:6a21:9986:b0:1c3:b2b3:442d with SMTP id adf61e73a8af0-1c3fdd3082fmr9450891637.40.1721396990438; Fri, 19 Jul 2024 06:49:50 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFo7ESVjai3vPwUqiXQxgtlNgRx0TFEoSnrj1a3SD+Rsx0zv4co4zEE+izm551vwVNo7gL7Rw== X-Received: by 2002:a05:6a21:9986:b0:1c3:b2b3:442d with SMTP id adf61e73a8af0-1c3fdd3082fmr9450865637.40.1721396989987; Fri, 19 Jul 2024 06:49:49 -0700 (PDT) Received: from localhost.localdomain ([115.96.152.71]) by smtp.googlemail.com with ESMTPSA id d9443c01a7336-1fd6f45cfe8sm4737825ad.249.2024.07.19.06.49.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Jul 2024 06:49:49 -0700 (PDT) From: Ani Sinha To: "Michael S. Tsirkin" , Marcel Apfelbaum , Paolo Bonzini , Richard Henderson , Eduardo Habkost Cc: Ani Sinha , qemu-trivial@nongnu.org, qemu-devel@nongnu.org Subject: [PATCH] hw/x86: add a couple of comments explaining how the kernel image is parsed Date: Fri, 19 Jul 2024 19:19:37 +0530 Message-ID: <20240719134937.3643-1-anisinha@redhat.com> X-Mailer: git-send-email 2.42.0 MIME-Version: 1.0 Received-SPF: pass client-ip=170.10.133.124; envelope-from=anisinha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Cosmetic: add comments in x86_load_linux() pointing to the kernel documentation so that users can better understand the code. CC: qemu-trivial@nongnu.org Signed-off-by: Ani Sinha Reviewed-by: Zhao Liu --- hw/i386/x86-common.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c index c0c66a0eb5..992ea1f25e 100644 --- a/hw/i386/x86-common.c +++ b/hw/i386/x86-common.c @@ -665,8 +665,11 @@ void x86_load_linux(X86MachineState *x86ms, exit(1); } - /* kernel protocol version */ - if (ldl_p(header + 0x202) == 0x53726448) { + /* + * kernel protocol version. + * Please see https://www.kernel.org/doc/Documentation/x86/boot.txt + */ + if (ldl_p(header + 0x202) == 0x53726448) /* Magic signature "HdrS" */ { protocol = lduw_p(header + 0x206); } else { /*