[IA64] Add __read_mostly support for IA64

sparc64, i386 and x86_64 have support for a special data section dedicated
to rarely updated data that is frequently read. The section was created to
avoid false sharing of those rarely read data with frequently written kernel
data.

This patch creates such a data section for ia64 and will group rarely written
data into this section.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

2 files changed, 4 insertions, 1 deletions

diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S
index 30d8564e9603..73af6267d2ef 100644
--- a/arch/ia64/kernel/vmlinux.lds.S
+++ b/arch/ia64/kernel/vmlinux.lds.S
@@ -177,6 +177,9 @@ SECTIONS
         }
   . = ALIGN(PAGE_SIZE);         /* make sure the gate page doesn't expose kernel data */
 
+  .data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET)
+        { *(.data.read_mostly) }
+
   .data.cacheline_aligned : AT(ADDR(.data.cacheline_aligned) - LOAD_OFFSET)
         { *(.data.cacheline_aligned) }
 
diff --git a/include/linux/cache.h b/include/linux/cache.h
index f6b5a46c5f82..0b7ecf3af78a 100644
--- a/include/linux/cache.h
+++ b/include/linux/cache.h
@@ -13,7 +13,7 @@
 #define SMP_CACHE_BYTES L1_CACHE_BYTES
 #endif
 
-#if defined(CONFIG_X86) || defined(CONFIG_SPARC64)
+#if defined(CONFIG_X86) || defined(CONFIG_SPARC64) || defined(CONFIG_IA64)
 #define __read_mostly __attribute__((__section__(".data.read_mostly")))
 #else
 #define __read_mostly