[Xen-devel] [PATCH v4 01/16] x86: remove LTO_REFERENCE_INITCALL()

[mcgrof]

From: "Luis R. Rodriguez" 

The setup for LTO never made it upstream, and although this has
some users, this is now really old stuff for a gcc 4.7 LTO problem.
We know that at least LTO_REFERENCE_INITCALL() work around can
be removed if LTO is not supported on v4.7 anymore.

As per Andi the DISABLE_LTO and LTO_CFLAGS are still neeeded though.

v3: added to this series, removing LTO_REFERENCE_INITCALL()
justifies that other future similar macros do not need
a respective LTO_REFERENCE_INITCALL() on them therefore
simplifying new code.

Acked-by: Andi Kleen 
Signed-off-by: Luis R. Rodriguez 
---
 include/linux/init.h | 20 +---
 1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index 1e5c131d5c9a..aa662ad80d9c 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -151,23 +151,6 @@ extern bool initcall_debug;
 
 #ifndef __ASSEMBLY__
 
-#ifdef CONFIG_LTO
-/* Work around a LTO gcc problem: when there is no reference to a variable
- * in a module it will be moved to the end of the program. This causes
- * reordering of initcalls which the kernel does not like.
- * Add a dummy reference function to avoid this. The function is
- * deleted by the linker.
- */
-#define LTO_REFERENCE_INITCALL(x) \
-   ; /* yes this is needed */  \
-   static __used __exit void *reference_##x(void)  \
-   {   \
-   return   \
-   }
-#else
-#define LTO_REFERENCE_INITCALL(x)
-#endif
-
 /* initcalls are now grouped by functionality into separate 
  * subsections. Ordering inside the subsections is determined
  * by link order. 
@@ -180,8 +163,7 @@ extern bool initcall_debug;
 
 #define __define_initcall(fn, id) \
static initcall_t __initcall_##fn##id __used \
-   __attribute__((__section__(".initcall" #id ".init"))) = fn; \
-   LTO_REFERENCE_INITCALL(__initcall_##fn##id)
+   __attribute__((__section__(".initcall" #id ".init"))) = fn;
 
 /*
  * Early initcalls run before initializing SMP.
-- 
2.9.2


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[Xen-devel] [PATCH v4 01/16] x86: remove LTO_REFERENCE_INITCALL()

[mcgrof]

From: "Luis R. Rodriguez" 

The setup for LTO never made it upstream, and although this has
some users, this is now really old stuff for a gcc 4.7 LTO problem.
We know that at least LTO_REFERENCE_INITCALL() work around can
be removed if LTO is not supported on v4.7 anymore.

As per Andi the DISABLE_LTO and LTO_CFLAGS are still neeeded though.

v3: added to this series, removing LTO_REFERENCE_INITCALL()
justifies that other future similar macros do not need
a respective LTO_REFERENCE_INITCALL() on them therefore
simplifying new code.

Acked-by: Andi Kleen 
Signed-off-by: Luis R. Rodriguez 
---
 include/linux/init.h | 20 +---
 1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/include/linux/init.h b/include/linux/init.h
index 1e5c131d5c9a..aa662ad80d9c 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -151,23 +151,6 @@ extern bool initcall_debug;
 
 #ifndef __ASSEMBLY__
 
-#ifdef CONFIG_LTO
-/* Work around a LTO gcc problem: when there is no reference to a variable
- * in a module it will be moved to the end of the program. This causes
- * reordering of initcalls which the kernel does not like.
- * Add a dummy reference function to avoid this. The function is
- * deleted by the linker.
- */
-#define LTO_REFERENCE_INITCALL(x) \
-   ; /* yes this is needed */  \
-   static __used __exit void *reference_##x(void)  \
-   {   \
-   return   \
-   }
-#else
-#define LTO_REFERENCE_INITCALL(x)
-#endif
-
 /* initcalls are now grouped by functionality into separate 
  * subsections. Ordering inside the subsections is determined
  * by link order. 
@@ -180,8 +163,7 @@ extern bool initcall_debug;
 
 #define __define_initcall(fn, id) \
static initcall_t __initcall_##fn##id __used \
-   __attribute__((__section__(".initcall" #id ".init"))) = fn; \
-   LTO_REFERENCE_INITCALL(__initcall_##fn##id)
+   __attribute__((__section__(".initcall" #id ".init"))) = fn;
 
 /*
  * Early initcalls run before initializing SMP.
-- 
2.9.2


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