From: Ian Campbell Date: Thu, 18 Oct 2012 07:26:17 +0000 (+0100) Subject: xen: arm: comment on why 64-bit xen_pfn_t is safe even on 32 bit X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=3ab0b83bf6a1e834f4b884150d8012990c75d25d;p=openwrt%2Fstaging%2Fblogic.git xen: arm: comment on why 64-bit xen_pfn_t is safe even on 32 bit Signed-off-by: Ian Campbell Signed-off-by: Konrad Rzeszutek Wilk --- 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;