From patchwork Fri Jan 10 22:29:09 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Salter X-Patchwork-Id: 3468381 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 5331DC02DC for ; Fri, 10 Jan 2014 22:32:58 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 6FD102013D for ; Fri, 10 Jan 2014 22:32:57 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7002720121 for ; Fri, 10 Jan 2014 22:32:56 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1W1kbd-00061d-IQ; Fri, 10 Jan 2014 22:31:10 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W1kbD-0005HJ-DU; Fri, 10 Jan 2014 22:30:43 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1W1kaV-0005Ac-Bx for linux-arm-kernel@lists.infradead.org; Fri, 10 Jan 2014 22:30:05 +0000 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s0AMTXkV009660 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Fri, 10 Jan 2014 17:29:34 -0500 Received: from deneb.redhat.com (ovpn-113-39.phx2.redhat.com [10.3.113.39]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id s0AMTQfh004120; Fri, 10 Jan 2014 17:29:32 -0500 From: Mark Salter To: linux-kernel@vger.kernel.org Subject: [PATCH 5/6] doc: arm64: add description of EFI stub support Date: Fri, 10 Jan 2014 17:29:09 -0500 Message-Id: <1389392950-22457-6-git-send-email-msalter@redhat.com> In-Reply-To: <1389392950-22457-1-git-send-email-msalter@redhat.com> References: <1389392950-22457-1-git-send-email-msalter@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140110_172959_725403_C4AD970C X-CRM114-Status: GOOD ( 19.78 ) X-Spam-Score: -7.0 (-------) Cc: Grant Likely , matt.fleming@intel.com, patches@linaro.org, Catalin Marinas , linux-doc@vger.kernel.org, Will Deacon , Leif Lindholm , roy.franz@linaro.org, linux-efi@vger.kernel.org, Rob Landley , Mark Salter , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add explanation of arm64 EFI stub and kernel image header changes needed to masquerade as a PE/COFF application. Signed-off-by: Mark Salter Acked-by: Grant Likely CC: linux-doc@vger.kernel.org CC: Rob Landley --- Documentation/arm64/booting.txt | 4 ++++ Documentation/efi-stub.txt | 12 +++++++++--- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt index a9691cc..aa95d38c 100644 --- a/Documentation/arm64/booting.txt +++ b/Documentation/arm64/booting.txt @@ -85,6 +85,10 @@ The decompressed kernel image contains a 64-byte header as follows: Header notes: - code0/code1 are responsible for branching to stext. +- when booting through EFI, code0/code1 are initially skipped. + res5 is an offset to the PE header and the PE header has the EFI + entry point (efi_stub_entry). When the stub has done its work, it + jumps to code0 to resume the normal boot process. The image must be placed at the specified offset (currently 0x80000) from the start of the system RAM and called there. The start of the diff --git a/Documentation/efi-stub.txt b/Documentation/efi-stub.txt index a55a0cd..d8ad0c1 100644 --- a/Documentation/efi-stub.txt +++ b/Documentation/efi-stub.txt @@ -12,6 +12,11 @@ arch/arm/boot/compressed/efi-header.S and arch/arm/boot/compressed/efi-stub.c. EFI stub code that is shared between architectures is in drivers/firmware/efi/efi-stub-helper.c. +For arm64, there is no compressed kernel support, so the Image itself +masquerades as a PE/COFF image and the EFI stub is linked into the +kernel. The arm64 EFI stub lives in arch/arm64/kernel/efi-entry.S +and arch/arm64/kernel/efi-stub.c. + By using the EFI boot stub it's possible to boot a Linux kernel without the use of a conventional EFI boot loader, such as grub or elilo. Since the EFI boot stub performs the jobs of a boot loader, in @@ -28,7 +33,8 @@ the extension the EFI firmware loader will refuse to execute it. It's not possible to execute bzImage.efi from the usual Linux file systems because EFI firmware doesn't have support for them. For ARM the arch/arm/boot/zImage should be copied to the system partition, and it -may not need to be renamed. +may not need to be renamed. Similarly for arm64, arch/arm64/boot/Image +should be copied but not necessarily renamed. **** Passing kernel parameters from the EFI shell @@ -72,7 +78,7 @@ is passed to bzImage.efi. **** The "dtb=" option -For the ARM architecture, we also need to be able to provide a device -tree to the kernel. This is done with the "dtb=" command line option, +For the ARM and arm64 architectures, we also need to be able to provide a +device tree to the kernel. This is done with the "dtb=" command line option, and is processed in the same manner as the "initrd=" option that is described above.