CONFIG_BOUNCE to avoid useless inclusion of bounce buffer logic

The bounce buffer logic is included on systems that do not need it.  If a
system does not have zones like ZONE_DMA and ZONE_HIGHMEM that can lead to
the use of bounce buffers then there is no need to reserve memory pools etc
etc.  This is true f.e.  for SGI Altix.

Also nicifies the Makefile and gets rid of the tricky "and" there.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b32564a..f78965f 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -624,7 +624,7 @@ extern unsigned long blk_max_low_pfn, blk_max_pfn;
  */
 #define BLK_DEFAULT_SG_TIMEOUT (60 * HZ)
 
-#ifdef CONFIG_MMU
+#ifdef CONFIG_BOUNCE
 extern int init_emergency_isa_pool(void);
 extern void blk_queue_bounce(request_queue_t *q, struct bio **bio);
 #else

diff --git a/mm/Kconfig b/mm/Kconfig
index 086af70..8618722 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -163,6 +163,10 @@ config ZONE_DMA_FLAG
        default "0" if !ZONE_DMA
        default "1"
 
+config BOUNCE
+       def_bool y
+       depends on BLOCK && MMU && (ZONE_DMA || HIGHMEM)
+
 config NR_QUICK
        int
        depends on QUICKLIST

diff --git a/mm/Makefile b/mm/Makefile
index a9148ea..245e33a 100644 (file)
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -13,9 +13,7 @@ obj-y                 := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
                           prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
                           $(mmu-y)
 
-ifeq ($(CONFIG_MMU)$(CONFIG_BLOCK),yy)
-obj-y                  += bounce.o
-endif
+obj-$(CONFIG_BOUNCE)   += bounce.o
 obj-$(CONFIG_SWAP)     += page_io.o swap_state.o swapfile.o thrash.o
 obj-$(CONFIG_HUGETLBFS)        += hugetlb.o
 obj-$(CONFIG_NUMA)     += mempolicy.o