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-rw-r--r--Documentation/x86/boot.txt27
1 files changed, 26 insertions, 1 deletions
diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index 406d82d5d2b..3edb4c2887a 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -57,6 +57,10 @@ Protocol 2.10: (Kernel 2.6.31) Added a protocol for relaxed alignment
Protocol 2.11: (Kernel 3.6) Added a field for offset of EFI handover
protocol entry point.
+Protocol 2.12: (Kernel 3.9) Added the xloadflags field and extension fields
+ to struct boot_params for for loading bzImage and ramdisk
+ above 4G in 64bit.
+
**** MEMORY LAYOUT
The traditional memory map for the kernel loader, used for Image or
@@ -182,7 +186,7 @@ Offset Proto Name Meaning
0230/4 2.05+ kernel_alignment Physical addr alignment required for kernel
0234/1 2.05+ relocatable_kernel Whether kernel is relocatable or not
0235/1 2.10+ min_alignment Minimum alignment, as a power of two
-0236/2 N/A pad3 Unused
+0236/2 2.12+ xloadflags Boot protocol option flags
0238/4 2.06+ cmdline_size Maximum size of the kernel command line
023C/4 2.07+ hardware_subarch Hardware subarchitecture
0240/8 2.07+ hardware_subarch_data Subarchitecture-specific data
@@ -582,6 +586,27 @@ Protocol: 2.10+
misaligned kernel. Therefore, a loader should typically try each
power-of-two alignment from kernel_alignment down to this alignment.
+Field name: xloadflags
+Type: read
+Offset/size: 0x236/2
+Protocol: 2.12+
+
+ This field is a bitmask.
+
+ Bit 0 (read): XLF_KERNEL_64
+ - If 1, this kernel has the legacy 64-bit entry point at 0x200.
+
+ Bit 1 (read): XLF_CAN_BE_LOADED_ABOVE_4G
+ - If 1, kernel/boot_params/cmdline/ramdisk can be above 4G.
+
+ Bit 2 (read): XLF_EFI_HANDOVER_32
+ - If 1, the kernel supports the 32-bit EFI handoff entry point
+ given at handover_offset.
+
+ Bit 3 (read): XLF_EFI_HANDOVER_64
+ - If 1, the kernel supports the 64-bit EFI handoff entry point
+ given at handover_offset + 0x200.
+
Field name: cmdline_size
Type: read
Offset/size: 0x238/4