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authorIan Campbell <Ian.Campbell@citrix.com>2012-10-18 08:26:17 +0100
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2012-10-19 15:18:01 -0400
commit3ab0b83bf6a1e834f4b884150d8012990c75d25d (patch)
tree85dd17c47102cd854bd13896bab8532d1f0d0e08
parent965c0aaafe3e75d4e65cd4ec862915869bde3abd (diff)
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xen: arm: comment on why 64-bit xen_pfn_t is safe even on 32 bit
Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
-rw-r--r--arch/arm/include/asm/xen/interface.h8
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/arm/include/asm/xen/interface.h b/arch/arm/include/asm/xen/interface.h
index 1d6ef9c2d1d9..5000397134b4 100644
--- a/arch/arm/include/asm/xen/interface.h
+++ b/arch/arm/include/asm/xen/interface.h
@@ -29,7 +29,13 @@
#ifndef __ASSEMBLY__
/* Explicitly size integers that represent pfns in the interface with
- * Xen so that we can have one ABI that works for 32 and 64 bit guests. */
+ * Xen so that we can have one ABI that works for 32 and 64 bit guests.
+ * Note that this means that the xen_pfn_t type may be capable of
+ * representing pfn's which the guest cannot represent in its own pfn
+ * type. However since pfn space is controlled by the guest this is
+ * fine since it simply wouldn't be able to create any sure pfns in
+ * the first place.
+ */
typedef uint64_t xen_pfn_t;
#define PRI_xen_pfn "llx"
typedef uint64_t xen_ulong_t;