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| author |   Ard Biesheuvel <ardb@kernel.org> | 2020-02-20 11:57:20 +0100 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2020-02-23 21:59:42 +0100 |
| commit | dc235d62fc60a6549238eda7ff29769457fe5663 (patch) | |
| tree | 5d6c21c1b23f0a07152a3e8e1e0c4ece2769425d | |
| parent | efi/libstub: Introduce symbolic constants for the stub major/minor version (diff) | |
| download | linux-dev-dc235d62fc60a6549238eda7ff29769457fe5663.tar.xz linux-dev-dc235d62fc60a6549238eda7ff29769457fe5663.zip | |
efi: Bump the Linux EFI stub major version number to #1
Now that we have introduced new, generic ways for the OS loader to
interface with Linux kernels during boot, we need to record this
fact in a way that allows loaders to discover this information, and
fall back to the existing methods for older kernels.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
| -rw-r--r-- | include/linux/pe.h | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/include/linux/pe.h b/include/linux/pe.h index e0869f3eadd6..8ad71d763a77 100644 --- a/include/linux/pe.h +++ b/include/linux/pe.h @@ -10,7 +10,25 @@ #include <linux/types.h> -#define LINUX_EFISTUB_MAJOR_VERSION 0x0 +/* + * Linux EFI stub v1.0 adds the following functionality: + * - Loading initrd from the LINUX_EFI_INITRD_MEDIA_GUID device path, + * - Loading/starting the kernel from firmware that targets a different + * machine type, via the entrypoint exposed in the .compat PE/COFF section. + * + * The recommended way of loading and starting v1.0 or later kernels is to use + * the LoadImage() and StartImage() EFI boot services, and expose the initrd + * via the LINUX_EFI_INITRD_MEDIA_GUID device path. + * + * Versions older than v1.0 support initrd loading via the image load options + * (using initrd=, limited to the volume from which the kernel itself was + * loaded), or via arch specific means (bootparams, DT, etc). + * + * On x86, LoadImage() and StartImage() can be omitted if the EFI handover + * protocol is implemented, which can be inferred from the version, + * handover_offset and xloadflags fields in the bootparams structure. + */ +#define LINUX_EFISTUB_MAJOR_VERSION 0x1 #define LINUX_EFISTUB_MINOR_VERSION 0x0 #define MZ_MAGIC 0x5a4d /* "MZ" */ |