x86, mm: Add pointer about Xen mmu requirement for alloc_low_pages
Add link for more information
279b706 x86,xen: introduce x86_init.mapping.pagetable_reserve
-v2: updated to commets from hpa to include commit name.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1353123563-3103-29-git-send-email-yinghai@kernel.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 02cea14..cb4f8ba 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -25,6 +25,15 @@
static unsigned long min_pfn_mapped;
+/*
+ * Pages returned are already directly mapped.
+ *
+ * Changing that is likely to break Xen, see commit:
+ *
+ * 279b706 x86,xen: introduce x86_init.mapping.pagetable_reserve
+ *
+ * for detailed information.
+ */
__ref void *alloc_low_pages(unsigned int num)
{
unsigned long pfn;