Configure out AIO support

This patchs adds the CONFIG_AIO option which allows to remove support
for asynchronous I/O operations, that are not necessarly used by
applications, particularly on embedded devices. As this is a
size-reduction option, it depends on CONFIG_EMBEDDED. It allows to
save ~7 kilobytes of kernel code/data:

   text	   data	    bss	    dec	    hex	filename
1115067	 119180	 217088	1451335	 162547	vmlinux
1108025	 119048	 217088	1444161	 160941	vmlinux.new
  -7042    -132       0   -7174   -1C06 +/-

This patch has been originally written by Matt Mackall
<mpm@selenic.com>, and is part of the Linux Tiny project.

[randy.dunlap@oracle.com: build fix]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/init/Kconfig b/init/Kconfig
index 8a8e2d00c40e..5ceff3249a2d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -713,6 +713,14 @@ config SHMEM
           option replaces shmem and tmpfs with the much simpler ramfs code,
           which may be appropriate on small systems without swap.
 
+config AIO
+        bool "Enable AIO support" if EMBEDDED
+        default y
+        help
+          This option enables POSIX asynchronous I/O which may by used
+          by some high performance threaded applications. Disabling
+          this option saves about 7k.
+
 config VM_EVENT_COUNTERS
         default y
         bool "Enable VM event counters for /proc/vmstat" if EMBEDDED