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-rw-r--r--arch/Kconfig19
-rw-r--r--arch/powerpc/Kconfig1
-rw-r--r--arch/x86/Kconfig1
3 files changed, 21 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 6093c0be58b..b0fabfa864f 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -27,6 +27,25 @@ config KPROBES
for kernel debugging, non-intrusive instrumentation and testing.
If in doubt, say "N".
+config HAVE_EFFICIENT_UNALIGNED_ACCESS
+ def_bool n
+ help
+ Some architectures are unable to perform unaligned accesses
+ without the use of get_unaligned/put_unaligned. Others are
+ unable to perform such accesses efficiently (e.g. trap on
+ unaligned access and require fixing it up in the exception
+ handler.)
+
+ This symbol should be selected by an architecture if it can
+ perform unaligned accesses efficiently to allow different
+ code paths to be selected for these cases. Some network
+ drivers, for example, could opt to not fix up alignment
+ problems with received packets if doing so would not help
+ much.
+
+ See Documentation/unaligned-memory-access.txt for more
+ information on the topic of unaligned memory accesses.
+
config KRETPROBES
def_bool y
depends on KPROBES && HAVE_KRETPROBES
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a487671c282..de6b49cd6be 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -112,6 +112,7 @@ config PPC
select HAVE_FTRACE
select HAVE_IDE
select HAVE_IOREMAP_PROT
+ select HAVE_EFFICIENT_UNALIGNED_ACCESS
select HAVE_KPROBES
select HAVE_ARCH_KGDB
select HAVE_KRETPROBES
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b2ddfcf0172..66f3ab05b18 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -28,6 +28,7 @@ config X86
select HAVE_FTRACE
select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
select HAVE_ARCH_KGDB if !X86_VOYAGER
+ select HAVE_EFFICIENT_UNALIGNED_ACCESS
config ARCH_DEFCONFIG
string