diff options
author | Jiri Kosina <jkosina@suse.cz> | 2013-12-19 09:08:03 -0500 |
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committer | Jiri Kosina <jkosina@suse.cz> | 2013-12-19 09:08:32 -0500 |
commit | e23c34bb41da65f354fb7eee04300c56ee48f60c (patch) | |
tree | 549fbe449d55273b81ef104a9755109bf4ae7817 /Documentation/x86 | |
parent | b481c2cb3534c85dca625973b33eba15f9af3e4c (diff) | |
parent | 319e2e3f63c348a9b66db4667efa73178e18b17d (diff) |
Merge branch 'master' into for-next
Sync with Linus' tree to be able to apply fixes on top of newer things
in tree (efi-stub).
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'Documentation/x86')
-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 44e6bb6ead10..000000000000 --- a/Documentation/x86/efi-stub.txt +++ /dev/null | |||
@@ -1,65 +0,0 @@ | |||
1 | The EFI Boot Stub | ||
2 | --------------------------- | ||
3 | |||
4 | On the x86 platform, a bzImage can masquerade as a PE/COFF image, | ||
5 | thereby convincing EFI firmware loaders to load it as an EFI | ||
6 | executable. The code that modifies the bzImage header, along with the | ||
7 | EFI-specific entry point that the firmware loader jumps to are | ||
8 | collectively known as the "EFI boot stub", and live in | ||
9 | arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c, | ||
10 | respectively. | ||
11 | |||
12 | By using the EFI boot stub it's possible to boot a Linux kernel | ||
13 | without the use of a conventional EFI boot loader, such as grub or | ||
14 | elilo. Since the EFI boot stub performs the jobs of a boot loader, in | ||
15 | a certain sense it *IS* the boot loader. | ||
16 | |||
17 | The EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option. | ||
18 | |||
19 | |||
20 | **** How to install bzImage.efi | ||
21 | |||
22 | The bzImage located in arch/x86/boot/bzImage must be copied to the EFI | ||
23 | System Partiion (ESP) and renamed with the extension ".efi". Without | ||
24 | the extension the EFI firmware loader will refuse to execute it. It's | ||
25 | not possible to execute bzImage.efi from the usual Linux file systems | ||
26 | because EFI firmware doesn't have support for them. | ||
27 | |||
28 | |||
29 | **** Passing kernel parameters from the EFI shell | ||
30 | |||
31 | Arguments to the kernel can be passed after bzImage.efi, e.g. | ||
32 | |||
33 | fs0:> bzImage.efi console=ttyS0 root=/dev/sda4 | ||
34 | |||
35 | |||
36 | **** The "initrd=" option | ||
37 | |||
38 | Like most boot loaders, the EFI stub allows the user to specify | ||
39 | multiple initrd files using the "initrd=" option. This is the only EFI | ||
40 | stub-specific command line parameter, everything else is passed to the | ||
41 | kernel when it boots. | ||
42 | |||
43 | The path to the initrd file must be an absolute path from the | ||
44 | beginning of the ESP, relative path names do not work. Also, the path | ||
45 | is an EFI-style path and directory elements must be separated with | ||
46 | backslashes (\). For example, given the following directory layout, | ||
47 | |||
48 | fs0:> | ||
49 | Kernels\ | ||
50 | bzImage.efi | ||
51 | initrd-large.img | ||
52 | |||
53 | Ramdisks\ | ||
54 | initrd-small.img | ||
55 | initrd-medium.img | ||
56 | |||
57 | to boot with the initrd-large.img file if the current working | ||
58 | directory is fs0:\Kernels, the following command must be used, | ||
59 | |||
60 | fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img | ||
61 | |||
62 | Notice how bzImage.efi can be specified with a relative path. That's | ||
63 | because the image we're executing is interpreted by the EFI shell, | ||
64 | which understands relative paths, whereas the rest of the command line | ||
65 | is passed to bzImage.efi. | ||