[IA64] Xen/ia64 XENMEM_exchange bug work around

xen-unstable.hg c/s 13366:ed73ff8440d8 revealed that
XENMEM_exchange has been broken on Xen/ia64.
This is work around for it until the right fix.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>

diff --git a/linux-2.6-xen-sparse/arch/ia64/xen/hypervisor.c b/linux-2.6-xen-sparse/arch/ia64/xen/hypervisor.c
index 695dc3bce53ae4bbf11c2dfd2484d83bf398e727..c9b542b98b0dadc9661b078b9dbfb290e1f11af5 100644 (file)
--- a/linux-2.6-xen-sparse/arch/ia64/xen/hypervisor.c
+++ b/linux-2.6-xen-sparse/arch/ia64/xen/hypervisor.c
@@ -205,6 +205,18 @@ static void contiguous_bitmap_clear(
 #define MAX_CONTIG_ORDER 7
 static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
 
+/* Width of DMA addresses. 30 bits is a b44 limitation. */
+#define DEFAULT_DMA_BITS 30
+static unsigned int xen_ia64_dma_bits = DEFAULT_DMA_BITS;
+
+static int __init
+setup_dma_bits(char *str)
+{
+       xen_ia64_dma_bits = simple_strtoul(str, NULL, 0);
+       return 0;
+}
+__setup("xen_ia64_dma_bits=", setup_dma_bits);
+
 /* Ensure multi-page extents are contiguous in machine memory. */
 int
 __xen_create_contiguous_region(unsigned long vstart,
@@ -234,6 +246,15 @@ __xen_create_contiguous_region(unsigned long vstart,
                .nr_exchanged = 0
        };
 
+       /*
+        * XXX xen/ia64 vmm bug work around
+        * the c/s 13366:ed73ff8440d8 of xen-unstable.hg revealed that
+        * XENMEM_exchange has been broken on Xen/ia64.
+        * This is work around for it until the right fix.
+        */
+       if (address_bits < xen_ia64_dma_bits)
+               return -ENOSYS;
+
        if (unlikely(order > MAX_CONTIG_ORDER))
                return -ENOMEM;