From 07dd3a3809f4dbda0d3f45e2bfbe47c012130ae6 Mon Sep 17 00:00:00 2001
From: Hartmut Birr <osexpert@googlemail.com>
Date: Sat, 14 Jun 2003 17:46:24 +0000
Subject: [PATCH] - Added a boot option for reducing the used memory size
 ('/maxmem=used_memory_in_mb').

svn path=/trunk/; revision=4890
---
 reactos/ntoskrnl/include/internal/mm.h |  3 ++-
 reactos/ntoskrnl/ke/main.c             | 37 +++++++++++++++++++++++---
 reactos/ntoskrnl/mm/mminit.c           | 13 ++++++---
 3 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/reactos/ntoskrnl/include/internal/mm.h b/reactos/ntoskrnl/include/internal/mm.h
index 4b47d0c9a0e..e6916975e85 100644
--- a/reactos/ntoskrnl/include/internal/mm.h
+++ b/reactos/ntoskrnl/include/internal/mm.h
@@ -319,7 +319,8 @@ VOID MmInit1(ULONG FirstKernelPhysAddress,
 	     ULONG LastKernelPhysAddress,
 	     ULONG LastKernelAddress,
        PADDRESS_RANGE BIOSMemoryMap,
-       ULONG AddressRangeCount);
+       ULONG AddressRangeCount,
+       ULONG MaxMemInMeg);
 VOID MmInit2(VOID);
 VOID MmInit3(VOID);
 NTSTATUS MmInitPagerThread(VOID);
diff --git a/reactos/ntoskrnl/ke/main.c b/reactos/ntoskrnl/ke/main.c
index 4eedaac2d42..233292653da 100644
--- a/reactos/ntoskrnl/ke/main.c
+++ b/reactos/ntoskrnl/ke/main.c
@@ -16,7 +16,7 @@
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
-/* $Id: main.c,v 1.160 2003/06/07 16:16:39 chorns Exp $
+/* $Id: main.c,v 1.161 2003/06/14 17:46:24 hbirr Exp $
  *
  * PROJECT:         ReactOS kernel
  * FILE:            ntoskrnl/ke/main.c
@@ -314,6 +314,8 @@ ExpInitializeExecutive(VOID)
   CHAR str[50];
   NTSTATUS Status;
   BOOLEAN SetupBoot;
+  PCHAR p1, p2;
+  ULONG MaxMem;
 
   /*
    * Fail at runtime if someone has changed various structures without
@@ -343,12 +345,41 @@ ExpInitializeExecutive(VOID)
   KeLowerIrql(DISPATCH_LEVEL);
   
   NtEarlyInitVdm();
-  
+
+  p1 = (PCHAR)KeLoaderBlock.CommandLine;
+
+  MaxMem = 0;
+  while(*p1 && (p2 = strchr(p1, '/')))
+  {
+     p2++;
+     if (!_strnicmp(p2, "MAXMEM", 6))
+     {
+        p2 += 6;
+        while (isspace(*p2)) p2++;
+	if (*p2 == '=')
+	{
+	   p2++;
+	   while(isspace(*p2)) p2++;
+	   if (isdigit(*p2))
+	   {
+	      while (isdigit(*p2))
+	      {
+	         MaxMem = MaxMem * 10 + *p2 - '0';
+		 p2++;
+	      }
+	      break;
+	   }
+	}
+     }
+     p1 = p2;
+  }
+
   MmInit1(FirstKrnlPhysAddr,
 	  LastKrnlPhysAddr,
 	  LastKernelAddress,
 	  (PADDRESS_RANGE)&KeMemoryMap,
-	  KeMemoryMapRangeCount);
+	  KeMemoryMapRangeCount,
+	  MaxMem > 8 ? MaxMem : 4096);
 
   /* Import ANSI code page table */
   for (i = 1; i < KeLoaderBlock.ModsCount; i++)
diff --git a/reactos/ntoskrnl/mm/mminit.c b/reactos/ntoskrnl/mm/mminit.c
index 875fc95517e..0214465e4ff 100644
--- a/reactos/ntoskrnl/mm/mminit.c
+++ b/reactos/ntoskrnl/mm/mminit.c
@@ -1,4 +1,4 @@
-/* $Id: mminit.c,v 1.46 2003/05/17 19:16:03 ekohl Exp $
+/* $Id: mminit.c,v 1.47 2003/06/14 17:46:24 hbirr Exp $
  *
  * COPYRIGHT:   See COPYING in the top directory
  * PROJECT:     ReactOS kernel 
@@ -209,7 +209,8 @@ VOID MmInit1(ULONG FirstKrnlPhysAddr,
 	     ULONG LastKrnlPhysAddr,
 	     ULONG LastKernelAddress,
 	     PADDRESS_RANGE BIOSMemoryMap,
-	     ULONG AddressRangeCount)
+	     ULONG AddressRangeCount,
+	     ULONG MaxMem)
 /*
  * FUNCTION: Initalize memory managment
  */
@@ -225,7 +226,6 @@ VOID MmInit1(ULONG FirstKrnlPhysAddr,
 		  LastKrnlPhysAddr,
 		  LastKernelAddress);
 
-   MmInitGlobalKernelPageDirectory();
 
    if ((BIOSMemoryMap != NULL) && (AddressRangeCount > 0))
      {
@@ -245,6 +245,11 @@ VOID MmInit1(ULONG FirstKrnlPhysAddr,
 	  }
      }
 
+   if (KeLoaderBlock.MemHigher >= (MaxMem - 1) * 1024)
+     {
+        KeLoaderBlock.MemHigher = (MaxMem - 1) * 1024;
+     }
+
    /*
     * FIXME: Set this based on the system command line
     */
@@ -252,6 +257,8 @@ VOID MmInit1(ULONG FirstKrnlPhysAddr,
    MmUserProbeAddress = (PVOID)0x7fff0000;
    MmHighestUserAddress = (PVOID)0x7ffeffff;
    
+   MmInitGlobalKernelPageDirectory();
+
    /*
     * Initialize memory managment statistics
     */