Merge branch 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pul x86/efi changes from Ingo Molnar:
 "This tree adds an EFI bootloader handover protocol, which, once
  supported on the bootloader side, will make bootup faster and might
  result in simpler bootloaders.

  The other change activates the EFI wall clock time accessors on x86-64
  as well, instead of the legacy RTC readout."

* 'x86-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, efi: Handover Protocol
  x86-64/efi: Use EFI to deal with platform wall clock

1 files changed, 41 insertions, 0 deletions

diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 473b32fd544..9efceff51bf 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -54,6 +54,9 @@ Protocol 2.10:	(Kernel 2.6.31) Added a protocol for relaxed alignment
 		beyond the kernel_alignment added, new init_size and
 		pref_address fields.  Added extended boot loader IDs.
 
+Protocol 2.11:	(Kernel 3.6) Added a field for offset of EFI handover
+		protocol entry point.
+
 **** MEMORY LAYOUT
 
 The traditional memory map for the kernel loader, used for Image or
@@ -189,6 +192,7 @@ Offset	Proto	Name		Meaning
 				of struct setup_data
 0258/8	2.10+	pref_address	Preferred loading address
 0260/4	2.10+	init_size	Linear memory required during initialization
+0264/4	2.11+	handover_offset	Offset of handover entry point
 
 (1) For backwards compatibility, if the setup_sects field contains 0, the
     real value is 4.
@@ -693,6 +697,16 @@ Offset/size:	0x260/4
   else
 	runtime_start = pref_address
 
+Field name:	handover_offset
+Type:		read
+Offset/size:	0x264/4
+
+  This field is the offset from the beginning of the kernel image to
+  the EFI handover protocol entry point. Boot loaders using the EFI
+  handover protocol to boot the kernel should jump to this offset.
+
+  See EFI HANDOVER PROTOCOL below for more details.
+
 
 **** THE IMAGE CHECKSUM
 
@@ -1013,3 +1027,30 @@ segment; __BOOS_CS must have execute/read permission, and __BOOT_DS
 must have read/write permission; CS must be __BOOT_CS and DS, ES, SS
 must be __BOOT_DS; interrupt must be disabled; %esi must hold the base
 address of the struct boot_params; %ebp, %edi and %ebx must be zero.
+
+**** EFI HANDOVER PROTOCOL
+
+This protocol allows boot loaders to defer initialisation to the EFI
+boot stub. The boot loader is required to load the kernel/initrd(s)
+from the boot media and jump to the EFI handover protocol entry point
+which is hdr->handover_offset bytes from the beginning of
+startup_{32,64}.
+
+The function prototype for the handover entry point looks like this,
+
+    efi_main(void *handle, efi_system_table_t *table, struct boot_params *bp)
+
+'handle' is the EFI image handle passed to the boot loader by the EFI
+firmware, 'table' is the EFI system table - these are the first two
+arguments of the "handoff state" as described in section 2.3 of the
+UEFI specification. 'bp' is the boot loader-allocated boot params.
+
+The boot loader *must* fill out the following fields in bp,
+
+    o hdr.code32_start
+    o hdr.cmd_line_ptr
+    o hdr.cmdline_size
+    o hdr.ramdisk_image (if applicable)
+    o hdr.ramdisk_size  (if applicable)
+
+All other fields should be zero.