MI VM: Make it possible to set size of superpage at boot instead of compile time.

In order to allow single kernel to use PAE pagetables on i386 if
hardware supports it, and fall back to classic two-level paging
structures if not, superpage code should be able to adopt to either 2M
or 4M superpages size.  There I make MI VM structures large enough to
track the biggest possible superpage, by allowing architecture to
define VM_NFREEORDER_MAX and VM_LEVEL_0_ORDER_MAX constants.
Corresponding VM_NFREEORDER and VM_LEVEL_0_ORDER symbols can be
defined as runtime values and must be less than the _MAX constants.
If architecture does not define _MAXs, it is assumed that _MAX ==
normal constant.

Reviewed by:	markj
Tested by:	pho (as part of the larger patch)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D18853

3 files changed, 14 insertions, 3 deletions

diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
index 5908c6df0696..bc7b2ae3f7e9 100644
--- a/sys/vm/vm_phys.c
+++ b/sys/vm/vm_phys.c
@@ -106,7 +106,8 @@ static struct rwlock_padalign vm_phys_fictitious_reg_lock;
 MALLOC_DEFINE(M_FICT_PAGES, "vm_fictitious", "Fictitious VM pages");
 
 static struct vm_freelist __aligned(CACHE_LINE_SIZE)
-    vm_phys_free_queues[MAXMEMDOM][VM_NFREELIST][VM_NFREEPOOL][VM_NFREEORDER];
+    vm_phys_free_queues[MAXMEMDOM][VM_NFREELIST][VM_NFREEPOOL]
+    [VM_NFREEORDER_MAX];
 
 static int __read_mostly vm_nfreelists;
 
diff --git a/sys/vm/vm_phys.h b/sys/vm/vm_phys.h
index 08c1a92d25f8..b8d3657c2f16 100644
--- a/sys/vm/vm_phys.h
+++ b/sys/vm/vm_phys.h
@@ -42,6 +42,10 @@
 
 #ifdef _KERNEL
 
+#ifndef VM_NFREEORDER_MAX
+#define	VM_NFREEORDER_MAX	VM_NFREEORDER
+#endif
+
 /* Domains must be dense (non-sparse) and zero-based. */
 struct mem_affinity {
 	vm_paddr_t start;
@@ -63,7 +67,7 @@ struct vm_phys_seg {
 	vm_paddr_t	end;
 	vm_page_t	first_page;
 	int		domain;
-	struct vm_freelist (*free_queues)[VM_NFREEPOOL][VM_NFREEORDER];
+	struct vm_freelist (*free_queues)[VM_NFREEPOOL][VM_NFREEORDER_MAX];
 };
 
 extern struct vm_phys_seg vm_phys_segs[];
diff --git a/sys/vm/vm_reserv.c b/sys/vm/vm_reserv.c
index 0cfc69f57e21..49ee4ca1f9e8 100644
--- a/sys/vm/vm_reserv.c
+++ b/sys/vm/vm_reserv.c
@@ -77,10 +77,15 @@ __FBSDID("$FreeBSD$");
 
 #if VM_NRESERVLEVEL > 0
 
+#ifndef VM_LEVEL_0_ORDER_MAX
+#define	VM_LEVEL_0_ORDER_MAX	VM_LEVEL_0_ORDER
+#endif
+
 /*
  * The number of small pages that are contained in a level 0 reservation
  */
 #define	VM_LEVEL_0_NPAGES	(1 << VM_LEVEL_0_ORDER)
+#define	VM_LEVEL_0_NPAGES_MAX	(1 << VM_LEVEL_0_ORDER_MAX)
 
 /*
  * The number of bits by which a physical address is shifted to obtain the
@@ -114,6 +119,7 @@ typedef	u_long		popmap_t;
  * The number of population map entries in a reservation
  */
 #define	NPOPMAP		howmany(VM_LEVEL_0_NPAGES, NBPOPMAP)
+#define	NPOPMAP_MAX	howmany(VM_LEVEL_0_NPAGES_MAX, NBPOPMAP)
 
 /*
  * Number of elapsed ticks before we update the LRU queue position.  Used
@@ -191,7 +197,7 @@ struct vm_reserv {
 	uint16_t	popcnt;			/* (r) # of pages in use */
 	int		lasttick;		/* (r) last pop update tick. */
 	char		inpartpopq;		/* (d) */
-	popmap_t	popmap[NPOPMAP];	/* (r) bit vector, used pages */
+	popmap_t	popmap[NPOPMAP_MAX];	/* (r) bit vector, used pages */
 };
 
 #define	vm_reserv_lockptr(rv)		(&(rv)->lock)