Make the size of the direct map easily configurable. Changing NDMPML4E

now suffices.

Increase the size of the direct map to 1TB.

An earler version of this patch was tested by sbruno@.

1 files changed, 9 insertions, 3 deletions

diff --git a/sys/amd64/include/pmap.h b/sys/amd64/include/pmap.h
index 45ccc64..c597cb2 100644
--- a/sys/amd64/include/pmap.h
+++ b/sys/amd64/include/pmap.h
@@ -125,15 +125,21 @@
 #define	NUPDPE		(NUPML4E*NPDPEPG)/* number of userland PDP pages */
 #define	NUPDE		(NUPDPE*NPDEPG)	/* number of userland PD entries */
 
-#define	NDMPML4E	1		/* number of dmap PML4 slots */
+/*
+ * NDMPML4E is the number of PML4 entries that are used to implement the
+ * direct map.  It must be a power of two.
+ */
+#define	NDMPML4E	2
 
 /*
- * The *PDI values control the layout of virtual memory
+ * The *PDI values control the layout of virtual memory.  The starting address
+ * of the direct map, which is controlled by DMPML4I, must be a multiple of
+ * its size.  (See the PHYS_TO_DMAP() and DMAP_TO_PHYS() macros.)
  */
 #define	PML4PML4I	(NPML4EPG/2)	/* Index of recursive pml4 mapping */
 
 #define	KPML4I		(NPML4EPG-1)	/* Top 512GB for KVM */
-#define	DMPML4I		(KPML4I-1)	/* Next 512GB down for direct map */
+#define	DMPML4I		rounddown(KPML4I - NDMPML4E, NDMPML4E) /* Below KVM */
 
 #define	KPDPI		(NPDPEPG-2)	/* kernbase at -2GB */