[S390] Optional ZONE_DMA for s390.

Disable ZONE_DMA on 31-bit. All memory is addressable by all
devices and we do not need any special memory pool.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 4 insertions, 2 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index eaaac3788110..d9425f59be91 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -8,8 +8,8 @@ config MMU
         default y
 
 config ZONE_DMA
-        bool
-        default y
+        def_bool y
+        depends on 64BIT
 
 config LOCKDEP_SUPPORT
         bool
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index b3e7c45efb63..916b72a8cde8 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -141,7 +141,9 @@ void __init paging_init(void)
         __raw_local_irq_ssm(ssm_mask);
 
         memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
+#ifdef CONFIG_ZONE_DMA
         max_zone_pfns[ZONE_DMA] = PFN_DOWN(MAX_DMA_ADDRESS);
+#endif
         max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
         free_area_init_nodes(max_zone_pfns);
 }