From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756620Ab3LEMxk (ORCPT ); Thu, 5 Dec 2013 07:53:40 -0500 Received: from mail-ea0-f182.google.com ([209.85.215.182]:62652 "EHLO mail-ea0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751299Ab3LEMxh (ORCPT ); Thu, 5 Dec 2013 07:53:37 -0500 From: Grant Likely Subject: Re: [PATCH 2/3] doc: arm64: add description of EFI stub support To: Mark Salter , linux-kernel@vger.kernel.org Cc: 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 In-Reply-To: <1385762712-17043-3-git-send-email-msalter@redhat.com> References: <1385762712-17043-1-git-send-email-msalter@redhat.com> < 1385762712-17043-3-git-send-email-msalter@redhat.com> Date: Thu, 05 Dec 2013 12:53:32 +0000 Message-Id: <20131205125332.5977FC407BC@trevor.secretlab.ca> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 29 Nov 2013 17:05:11 -0500, Mark Salter wrote: Even documentation updates should have a mildly sane commit text. State why these changes came about. Give a future reader at least some clues as to why these changes were made now. Otherwise: Acked-by: Grant Likely g. > Signed-off-by: Mark Salter > CC: Catalin Marinas > CC: Will Deacon > CC: linux-arm-kernel@lists.infradead.org > CC: matt.fleming@intel.com > CC: linux-efi@vger.kernel.org > CC: linux-doc@vger.kernel.org > CC: Rob Landley > CC: Leif Lindholm > CC: roy.franz@linaro.org > --- > Documentation/arm64/booting.txt | 4 ++++ > Documentation/efi-stub.txt | 10 ++++++++-- > 2 files changed, 12 insertions(+), 2 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 19e897c..c2a4b11 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 > +For ARM and arm64 architecture, 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 process in the same manner as the "initrd=" option that is described > above. > -- > 1.8.3.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel