From 2a7326b5bbafac4c96bcdb944b2a773593030b96 Mon Sep 17 00:00:00 2001
From: Christoph Lameter <clameter@sgi.com>
Date: Tue, 17 Jul 2007 04:03:37 -0700
Subject: [PATCH] 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>
---
 include/linux/blkdev.h | 2 +-
 mm/Kconfig             | 4 ++++
 mm/Makefile            | 4 +---
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b32564a1e105c..f78965fc6426f 100644
--- 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 086af703da433..86187221e78fd 100644
--- 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 a9148ea329aab..245e33ab00c44 100644
--- 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
-- 
GitLab