Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753263Ab3IVWpb (ORCPT ); Sun, 22 Sep 2013 18:45:31 -0400 Received: from mail-qe0-f53.google.com ([209.85.128.53]:34045 "EHLO mail-qe0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752784Ab3IVWp0 (ORCPT ); Sun, 22 Sep 2013 18:45:26 -0400 From: Roy Franz To: linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, matt.fleming@intel.com Cc: leif.lindholm@linaro.org, grant.likely@linaro.org, msalter@redhat.com, Roy Franz Subject: [PATCH 01/18] EFI stub documentation updates Date: Sun, 22 Sep 2013 15:45:25 -0700 Message-Id: <1379889942-3135-2-git-send-email-roy.franz@linaro.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1379889942-3135-1-git-send-email-roy.franz@linaro.org> References: <1379889942-3135-1-git-send-email-roy.franz@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6403 Lines: 175 Move efi-stub.txt out of x86 directory and into common directory in preparation for adding ARM EFI stub support. Signed-off-by: Roy Franz --- Documentation/efi-stub.txt | 65 ++++++++++++++++++++++++++++++++++++++++ Documentation/x86/efi-stub.txt | 65 ---------------------------------------- arch/x86/Kconfig | 2 +- 3 files changed, 66 insertions(+), 66 deletions(-) create mode 100644 Documentation/efi-stub.txt delete mode 100644 Documentation/x86/efi-stub.txt diff --git a/Documentation/efi-stub.txt b/Documentation/efi-stub.txt new file mode 100644 index 0000000..44e6bb6 --- /dev/null +++ b/Documentation/efi-stub.txt @@ -0,0 +1,65 @@ + The EFI Boot Stub + --------------------------- + +On the x86 platform, a bzImage can masquerade as a PE/COFF image, +thereby convincing EFI firmware loaders to load it as an EFI +executable. The code that modifies the bzImage header, along with the +EFI-specific entry point that the firmware loader jumps to are +collectively known as the "EFI boot stub", and live in +arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c, +respectively. + +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 +a certain sense it *IS* the boot loader. + +The EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option. + + +**** How to install bzImage.efi + +The bzImage located in arch/x86/boot/bzImage must be copied to the EFI +System Partiion (ESP) and renamed with the extension ".efi". Without +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. + + +**** Passing kernel parameters from the EFI shell + +Arguments to the kernel can be passed after bzImage.efi, e.g. + + fs0:> bzImage.efi console=ttyS0 root=/dev/sda4 + + +**** The "initrd=" option + +Like most boot loaders, the EFI stub allows the user to specify +multiple initrd files using the "initrd=" option. This is the only EFI +stub-specific command line parameter, everything else is passed to the +kernel when it boots. + +The path to the initrd file must be an absolute path from the +beginning of the ESP, relative path names do not work. Also, the path +is an EFI-style path and directory elements must be separated with +backslashes (\). For example, given the following directory layout, + +fs0:> + Kernels\ + bzImage.efi + initrd-large.img + + Ramdisks\ + initrd-small.img + initrd-medium.img + +to boot with the initrd-large.img file if the current working +directory is fs0:\Kernels, the following command must be used, + + fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img + +Notice how bzImage.efi can be specified with a relative path. That's +because the image we're executing is interpreted by the EFI shell, +which understands relative paths, whereas the rest of the command line +is passed to bzImage.efi. diff --git a/Documentation/x86/efi-stub.txt b/Documentation/x86/efi-stub.txt deleted file mode 100644 index 44e6bb6..0000000 --- a/Documentation/x86/efi-stub.txt +++ /dev/null @@ -1,65 +0,0 @@ - The EFI Boot Stub - --------------------------- - -On the x86 platform, a bzImage can masquerade as a PE/COFF image, -thereby convincing EFI firmware loaders to load it as an EFI -executable. The code that modifies the bzImage header, along with the -EFI-specific entry point that the firmware loader jumps to are -collectively known as the "EFI boot stub", and live in -arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c, -respectively. - -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 -a certain sense it *IS* the boot loader. - -The EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option. - - -**** How to install bzImage.efi - -The bzImage located in arch/x86/boot/bzImage must be copied to the EFI -System Partiion (ESP) and renamed with the extension ".efi". Without -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. - - -**** Passing kernel parameters from the EFI shell - -Arguments to the kernel can be passed after bzImage.efi, e.g. - - fs0:> bzImage.efi console=ttyS0 root=/dev/sda4 - - -**** The "initrd=" option - -Like most boot loaders, the EFI stub allows the user to specify -multiple initrd files using the "initrd=" option. This is the only EFI -stub-specific command line parameter, everything else is passed to the -kernel when it boots. - -The path to the initrd file must be an absolute path from the -beginning of the ESP, relative path names do not work. Also, the path -is an EFI-style path and directory elements must be separated with -backslashes (\). For example, given the following directory layout, - -fs0:> - Kernels\ - bzImage.efi - initrd-large.img - - Ramdisks\ - initrd-small.img - initrd-medium.img - -to boot with the initrd-large.img file if the current working -directory is fs0:\Kernels, the following command must be used, - - fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img - -Notice how bzImage.efi can be specified with a relative path. That's -because the image we're executing is interpreted by the EFI shell, -which understands relative paths, whereas the rest of the command line -is passed to bzImage.efi. diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index b32ebf9..ec65b51 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1579,7 +1579,7 @@ config EFI_STUB This kernel feature allows a bzImage to be loaded directly by EFI firmware without the use of a bootloader. - See Documentation/x86/efi-stub.txt for more information. + See Documentation/efi-stub.txt for more information. config SECCOMP def_bool y -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/