diff options
Diffstat (limited to 'Documentation/x86/efi-stub.txt')
| -rw-r--r-- | Documentation/x86/efi-stub.txt | 65 |
1 files changed, 0 insertions, 65 deletions
diff --git a/Documentation/x86/efi-stub.txt b/Documentation/x86/efi-stub.txt deleted file mode 100644 index 44e6bb6ead1..00000000000 --- 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. |