diff options
authorDeepak Saxena <>2005-09-03 15:54:58 -0700
committerLinus Torvalds <>2005-09-05 00:05:46 -0700
commitfd195c49fb17a21e232f50bddb2267150053cf34 (patch)
parent9b4ee40ebbbaf3f8c775b023d89ceedda1167d79 (diff)
[PATCH] arm: allow for arch-specific IOREMAP_MAX_ORDER
Version 6 of the ARM architecture introduces the concept of 16MB pages (supersections) and 36-bit (40-bit actually, but nobody uses this) physical addresses. 36-bit addressed memory and I/O and ARMv6 can only be mapped using supersections and the requirement on these is that both virtual and physical addresses be 16MB aligned. In trying to add support for ioremap() of 36-bit I/O, we run into the issue that get_vm_area() allows for a maximum of 512K alignment via the IOREMAP_MAX_ORDER constant. To work around this, we can: - Allocate a larger VM area than needed (size + (1ul << IOREMAP_MAX_ORDER)) and then align the pointer ourselves, but this ends up with 512K of wasted VM per ioremap(). - Provide a new __get_vm_area_aligned() API and make __get_vm_area() sit on top of this. I did this and it works but I don't like the idea adding another VM API just for this one case. - My preferred solution which is to allow the architecture to override the IOREMAP_MAX_ORDER constant with it's own version. Signed-off-by: Deepak Saxena <> Cc: Russell King <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2 files changed, 8 insertions, 2 deletions
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 6409d9cf5965..b244f69ef682 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -10,6 +10,14 @@
#define VM_MAP 0x00000004 /* vmap()ed pages */
/* bits [20..32] reserved for arch specific ioremap internals */
+ * Maximum alignment for ioremap() regions.
+ * Can be overriden by arch-specific value.
+ */
+#define IOREMAP_MAX_ORDER (7 + PAGE_SHIFT) /* 128 pages */
struct vm_struct {
void *addr;
unsigned long size;
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 8ff16a1eee6a..67b358e57ef6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -158,8 +158,6 @@ int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
return err;
-#define IOREMAP_MAX_ORDER (7 + PAGE_SHIFT) /* 128 pages */
struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
unsigned long start, unsigned long end)