introduce HAVE_EFFICIENT_UNALIGNED_ACCESS Kconfig symbol

[linux-2.6-omap-h63xx.git] / arch / Kconfig

diff --git a/arch/Kconfig b/arch/Kconfig
index 6093c0be58b017a1a325d2b4c29b0f6ff1e771ba..b0fabfa864ffa12be40160f9b2c6d3b1010ab149 100644 (file)
--- 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