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From: Olivier Houchard <cognet@FreeBSD.org>
Date: Thu, 22 Jan 2009 15:36:12 +0000 (UTC)
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Subject: svn commit: r187592 - head/sys/arm/include
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Author: cognet
Date: Thu Jan 22 15:36:11 2009
New Revision: 187592
URL: http://svn.freebsd.org/changeset/base/187592

Log:
  Add a comment explaining what ARM_KERN_DIRECTMAP is all about.
  
  Suggested by:	raj

Modified:
  head/sys/arm/include/vmparam.h

Modified: head/sys/arm/include/vmparam.h
==============================================================================
--- head/sys/arm/include/vmparam.h	Thu Jan 22 15:35:54 2009	(r187591)
+++ head/sys/arm/include/vmparam.h	Thu Jan 22 15:36:11 2009	(r187592)
@@ -97,6 +97,13 @@
 
 #define VM_MIN_ADDRESS          (0x00001000)
 #ifdef ARM_USE_SMALL_ALLOC
+/* 
+ * ARM_KERN_DIRECTMAP is used to make sure there's enough space between
+ * VM_MAXUSER_ADDRESS and KERNBASE to map the whole memory.
+ * It has to be a compile-time constant, even if arm_init_smallalloc(),
+ * which will do the mapping, gets the real amount of memory at runtime,
+ * because VM_MAXUSER_ADDRESS is a constant.
+ */
 #ifndef ARM_KERN_DIRECTMAP
 #define ARM_KERN_DIRECTMAP 512 * 1024 * 1024 /* 512 MB */
 #endif