[PATCH] memblock/nobootmem: Allow alloc_bootmem take 0 as low limit

[PATCH] memblock/nobootmem: Allow alloc_bootmem take 0 as low limit

[Yinghai Lu]

bootmem wrapper with memblock support top-down now, So do not need set low limit
to __pa(MAX_DMA_ADDRESS).

the logic should be: good to allocate above __pa(MAX_DMA_ADDRESS), but it is ok if we
can not find above 16M on system that have small amount of RAM.

Need to apply this one after
	[PATCH] mm: Use alloc_bootmem_node_nopanic on really needed path

Signed-off-by: Yinghai LU <yinghai@kernel.org>

---
 include/linux/bootmem.h |   25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

Index: linux-2.6/include/linux/bootmem.h
===================================================================
--- linux-2.6.orig/include/linux/bootmem.h
+++ linux-2.6/include/linux/bootmem.h
@@ -99,24 +99,31 @@ extern void *__alloc_bootmem_low_node(pg
 				      unsigned long align,
 				      unsigned long goal);
 
+#ifdef CONFIG_NO_BOOTMEM
+/* We are using top down, so it is safe to use 0 here */
+#define BOOTMEM_LOW_LIMIT 0
+#else
+#define BOOTMEM_LOW_LIMIT __pa(MAX_DMA_ADDRESS)
+#endif
+
 #define alloc_bootmem(x) \
-	__alloc_bootmem(x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem(x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_align(x, align) \
-	__alloc_bootmem(x, align, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem(x, align, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_nopanic(x) \
-	__alloc_bootmem_nopanic(x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem_nopanic(x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_pages(x) \
-	__alloc_bootmem(x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem(x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_pages_nopanic(x) \
-	__alloc_bootmem_nopanic(x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem_nopanic(x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_node(pgdat, x) \
-	__alloc_bootmem_node(pgdat, x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem_node(pgdat, x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_node_nopanic(pgdat, x) \
-	__alloc_bootmem_node_nopanic(pgdat, x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem_node_nopanic(pgdat, x, SMP_CACHE_BYTES, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_pages_node(pgdat, x) \
-	__alloc_bootmem_node(pgdat, x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem_node(pgdat, x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
 #define alloc_bootmem_pages_node_nopanic(pgdat, x) \
-	__alloc_bootmem_node_nopanic(pgdat, x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
+	__alloc_bootmem_node_nopanic(pgdat, x, PAGE_SIZE, BOOTMEM_LOW_LIMIT)
 
 #define alloc_bootmem_low(x) \
 	__alloc_bootmem_low(x, SMP_CACHE_BYTES, 0)