From 7290545b37b990f88ce4868276e6341c59bf623d Mon Sep 17 00:00:00 2001
From: peter <peter@FreeBSD.org>
Date: Fri, 21 Sep 2001 06:23:03 +0000
Subject: Introduce a new option, KVA_SPACE, which can be used to reconfigure
 the size of the kernel virtual address space relatively painlessly. Userland
 will adapt via the exported kernbase symbol.  Increasing this causes the user
 part of address space to reduce.

---
 sys/amd64/include/pmap.h | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

(limited to 'sys/amd64/include')

diff --git a/sys/amd64/include/pmap.h b/sys/amd64/include/pmap.h
index ab923fb..a6eabae 100644
--- a/sys/amd64/include/pmap.h
+++ b/sys/amd64/include/pmap.h
@@ -83,19 +83,28 @@
 #define PGEX_U		0x04	/* access from User mode (UPL) */
 
 /*
+ * Size of Kernel address space.  This is the number of page table pages
+ * (4MB each) to use for the kernel.  256 pages == 1 Gigabyte.
+ * This **MUST** be a multiple of 4 (eg: 252, 256, 260, etc).
+ */
+#ifndef KVA_PAGES
+#define KVA_PAGES	256
+#endif
+
+/*
  * Pte related macros
  */
 #define VADDR(pdi, pti) ((vm_offset_t)(((pdi)<<PDRSHIFT)|((pti)<<PAGE_SHIFT)))
 
 #ifndef NKPT
-#define	NKPT			30	/* actual number of kernel page tables */
+#define	NKPT		30	/* actual number of kernel page tables */
 #endif
 #ifndef NKPDE
 #ifdef SMP
-#define NKPDE			254	/* addressable number of page tables/pde's */
+#define NKPDE	(KVA_PAGES - 2)	/* addressable number of page tables/pde's */
 #else
-#define NKPDE			255	/* addressable number of page tables/pde's */
-#endif	/* SMP */
+#define NKPDE	(KVA_PAGES - 1)	/* addressable number of page tables/pde's */
+#endif
 #endif
 
 /*
-- 
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