@@ -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" */
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> --- include/linux/pe.h | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-)