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Subject[PATCH 5/7] x86/boot: Mark global variables as static
From: Arvind Sankar <>

Mike Lothian reports that after commit
964124a97b97 ("efi/x86: Remove extra headroom for setup block")
gcc 10.1.0 fails with

HOSTCC arch/x86/boot/tools/build
error: linker defined: multiple definition of '_end'
/tmp/ccEkW0jM.o: previous definition here
collect2: error: ld returned 1 exit status
make[1]: *** [scripts/ arch/x86/boot/tools/build] Error 1
make: *** [arch/x86/Makefile:303: bzImage] Error 2

The issue is with the _end variable that was added, to hold the end of
the compressed kernel from zoffsets.h (ZO__end). The name clashes with
the linker-defined _end symbol that indicates the end of the build
program itself.

Even when there is no compile-time error, this causes build to use
memory past the end of its .bss section.

To solve this, mark _end as static, and for symmetry, mark the rest of
the variables that keep track of symbols from the compressed kernel as
static as well.

Fixes: 964124a97b97 ("efi/x86: Remove extra headroom for setup block")
Reported-by: Mike Lothian <>
Tested-by: Mike Lothian <>
Signed-off-by: Arvind Sankar <>
Signed-off-by: Ard Biesheuvel <>
arch/x86/boot/tools/build.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c
index 8f8c8e386cea..c8b8c1a8d1fc 100644
--- a/arch/x86/boot/tools/build.c
+++ b/arch/x86/boot/tools/build.c
@@ -59,14 +59,14 @@ u8 buf[SETUP_SECT_MAX*512];

-unsigned long efi32_stub_entry;
-unsigned long efi64_stub_entry;
-unsigned long efi_pe_entry;
-unsigned long efi32_pe_entry;
-unsigned long kernel_info;
-unsigned long startup_64;
-unsigned long _ehead;
-unsigned long _end;
+static unsigned long efi32_stub_entry;
+static unsigned long efi64_stub_entry;
+static unsigned long efi_pe_entry;
+static unsigned long efi32_pe_entry;
+static unsigned long kernel_info;
+static unsigned long startup_64;
+static unsigned long _ehead;
+static unsigned long _end;


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