[patch 7/7 v2] x86: add xloadflags bit for efi runtime support on kexec

[dyoung]

Old kexec-tools can not load new kernel. The reason is previously kexec-tools
do not fill efi_info in x86 setup header thus efi init fail and switch
to noefi boot. In new kexec-tools it will by default fill efi_info and
pass other efi required infomation to 2nd kernel so kexec kernel efi
initialization will success finally.

To prevent from breaking userspace, add a new xloadflags bit so kexec-tools
will check the flag and switch to old logic.

Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
---
 arch/x86/boot/header.S                |    9 ++++++++-
 arch/x86/include/uapi/asm/bootparam.h |    1 +
 2 files changed, 9 insertions(+), 1 deletion(-)

--- linux-2.6.orig/arch/x86/boot/header.S
+++ linux-2.6/arch/x86/boot/header.S
@@ -391,7 +391,14 @@ xloadflags:
 #else
 # define XLF23 0
 #endif
-			.word XLF0 | XLF1 | XLF23
+
+#if defined(CONFIG_X86_64) && defined(CONFIG_EFI)
+# define XLF4 XLF_EFI_KEXEC
+#else
+# define XLF4 0
+#endif
+
+			.word XLF0 | XLF1 | XLF23 | XLF4
 
 cmdline_size:   .long   COMMAND_LINE_SIZE-1     #length of the command line,
                                                 #added with boot protocol
--- linux-2.6.orig/arch/x86/include/uapi/asm/bootparam.h
+++ linux-2.6/arch/x86/include/uapi/asm/bootparam.h
@@ -24,6 +24,7 @@
 #define XLF_CAN_BE_LOADED_ABOVE_4G	(1<<1)
 #define XLF_EFI_HANDOVER_32		(1<<2)
 #define XLF_EFI_HANDOVER_64		(1<<3)
+#define XLF_EFI_KEXEC			(1<<4)
 
 #ifndef __ASSEMBLY__
 

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