[PATCH v4 09/12] x86: add xloadflags bit for efi runtime support on kexec

Dave Young
2013-11-26T05:57:54Z

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.

changelog:
Matt: +&& defined(CONFIG_KEXEC)
HPA: document the flag.

Signed-off-by: Dave Young <dyoung-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
Documentation/x86/boot.txt | 3 +++
arch/x86/boot/header.S | 9 ++++++++-
arch/x86/include/uapi/asm/bootparam.h | 1 +
3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/Documentation/x86/boot.txt b/Documentation/x86/boot.txt
index f4f268c..cb81741d 100644
--- a/Documentation/x86/boot.txt
+++ b/Documentation/x86/boot.txt
@@ -608,6 +608,9 @@ Protocol: 2.12+
- If 1, the kernel supports the 64-bit EFI handoff entry point
given at handover_offset + 0x200.

+ Bit 4 (read): XLF_EFI_KEXEC
+ - If 1, the kernel supports kexec EFI boot with EFI runtime support.
+
Field name: cmdline_size
Type: read
Offset/size: 0x238/4
diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S
index 9ec06a1..ec3b8ba 100644
--- a/arch/x86/boot/header.S
+++ b/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) && defined(CONFIG_KEXEC)
+# 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
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index ed6afc9..505eecf 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/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__

--
1.8.3.1