diff --git a/reactos/iface/native/genntdll.c b/reactos/iface/native/genntdll.c
index e390c06d0d8..d9f752db0c9 100644
--- a/reactos/iface/native/genntdll.c
+++ b/reactos/iface/native/genntdll.c
@@ -1,9 +1,15 @@
-/*
+/* $Id: genntdll.c,v 1.6 1999/06/17 00:10:30 ea Exp $
+ *
  * COPYRIGHT:             See COPYING in the top level directory
  * PROJECT:               ReactOS version of ntdll
  * FILE:                  iface/native/genntdll.c
  * PURPOSE:               Generates the system call stubs in ntdll
  * CHANGE HISTORY:	  Added a '@xx' to deal with stdcall [ Ariadne ]
+ * 	19990616 (ea)
+ * 		Four arguments now required; 4th is the file
+ * 		for ntoskrnl ZwXXX functions (which are merely calls
+ * 		to twin NtXXX calls, via int 0x2e (x86).
+ * 		
  */
 
 /* INCLUDE ******************************************************************/
@@ -17,129 +23,195 @@
 
 #define PARAMETERIZED_LIBS
 
+#define VERBOSE
+
 /* FUNCTIONS ****************************************************************/
 
-int process(FILE* in, FILE* out, FILE *out2)
+int
+process(
+	FILE	* in,
+	FILE	* out,
+	FILE	* out2,
+	FILE	* out3
+	)
 {
-   char line[255];
-   char* s;
-   char* name;
-   char* name2;
-   int value;
-   char* nr_args;
-   char* stmp;
+	char		line [255];
+	char		* s;
+	char		* name;		/* NtXXX name */
+	char		* name2;	/* ZwXXX name */
+	int		value;
+	char		* nr_args;	/* stack_size / machine_word_size */
+	char		* stmp;
    
-   unsigned char first1 = TRUE;
-   
-   fprintf(out,"// Machine generated, don't edit\n");
-   fprintf(out,"\n\n");
-   
-   fprintf(out2,"// Machine generated, don't edit\n");
-   fprintf(out2,"\n\n");
-   //fprintf(out2,"#include <ntddk.h>");
-   fprintf(out2,"\n\n\n");
-   fprintf(out2,"SERVICE_TABLE _SystemServiceTable[256] = {\n");
- 
+	unsigned char	first1 = TRUE;
 
-   value = 0;
-   while (!feof(in) && fgets(line,255,in) != NULL)
-     {
-//	fgets(line,255,in);
-	if ((s=(char *)strchr(line,13))!=NULL)
-	  {
-	     *s=0;
-	  }
-	s=&line[0];
-	if ((*s)!='#' && (*s) != 0)
-	  {
-	     name = (char *)strtok(s," \t");
-	     name2 = (char *)strtok(NULL," \t");
-//	     value = strtok(NULL," \t");
-	     nr_args = (char *)strtok(NULL," \t");
+	/*
+	 * NTDLL stubs file header
+	 */
+	fprintf(out,"// Machine generated, don't edit\n");
+	fprintf(out,"\n\n");
+	/*
+	 * Service table header
+	 */
+	fprintf(out2,"// Machine generated, don't edit\n");
+	fprintf(out2,"\n\n");
+	//fprintf(out2,"#include <ntddk.h>");
+	fprintf(out2,"\n\n\n");
+	fprintf(out2,"SERVICE_TABLE _SystemServiceTable[256] = {\n");
+ 	/*
+	 * NTOSKRNL Zw functions stubs header
+	 */
+	fprintf(out3,"// Machine generated, don't edit\n");
+	fprintf(out3,"\n\n");
+   
+	/*
+	 * Scan the database. DB is a text file; each line
+	 * is a record, which contains data for one system
+	 * function. Each record has three columns:
+	 *
+	 * NT_NAME	(e.g. NtCreateProcess)
+	 * ZW_NAME	(e.g. ZwCreateProcess)
+	 * STACK_SIZE	(in machine words: for x[3456]86
+	 * 		processors a machine word is 4 bytes)
+	 */
+	value = 0;
+	while (!feof(in) && fgets(line,255,in) != NULL)
+	{
+		//fgets(line,255,in);
+		if ((s=(char *)strchr(line,13))!=NULL)
+		{
+			*s=0;
+		}
+		s = & line[0];
+		if ((*s)!='#' && (*s) != 0)
+		{
+			name = (char *)strtok(s," \t");
+			name2 = (char *)strtok(NULL," \t");
+			//value = strtok(NULL," \t");
+			nr_args = (char *)strtok(NULL," \t");
 	     
-	     if ((stmp=strchr(nr_args,'\n'))!=NULL)
-	       {
-		  *stmp=0;
-	       }
-	     
-//	     printf("name %s value %d\n",name,value);
-#ifdef PARAMETERIZED_LIBS
-         fprintf(out,"__asm__(\"\\n\\t.global _%s@%s\\n\\t\"\n",name,nr_args);
-         fprintf(out,"\".global _%s@%s\\n\\t\"\n",name2,nr_args);
-         fprintf(out,"\"_%s@%s:\\n\\t\"\n",name,nr_args);
-         fprintf(out,"\"_%s@%s:\\n\\t\"\n",name2,nr_args);
-#else
-         fprintf(out,"__asm__(\"\\n\\t.global _%s\\n\\t\"\n",name);
-         fprintf(out,"\".global _%s\\n\\t\"\n",name2);
-         fprintf(out,"\"_%s:\\n\\t\"\n",name);
-         fprintf(out,"\"_%s:\\n\\t\"\n",name2);
+			if ((stmp=strchr(nr_args,'\n'))!=NULL)
+			{
+				*stmp=0;
+			}
+#ifdef VERBOSE
+			printf("name = \"%s\" value = %d\n",name,value);
 #endif
-         fprintf(out,"\t\"mov\t$%d,%%eax\\n\\t\"\n",value);
-         fprintf(out,"\t\"lea\t4(%%esp),%%edx\\n\\t\"\n");
-         fprintf(out,"\t\"int\t$0x2E\\n\\t\"\n");
-         fprintf(out,"\t\"ret\t$%s\\n\\t\");\n\n",nr_args);
+			/*
+			 * Write the NTDLL stub for the current
+			 * system call: NtXXX and ZwXXX symbols
+			 * are aliases.
+			 */
+#ifdef PARAMETERIZED_LIBS
+			fprintf(out,"__asm__(\"\\n\\t.global _%s@%s\\n\\t\"\n",name,nr_args);
+			fprintf(out,"\".global _%s@%s\\n\\t\"\n",name2,nr_args);
+			fprintf(out,"\"_%s@%s:\\n\\t\"\n",name,nr_args);
+			fprintf(out,"\"_%s@%s:\\n\\t\"\n",name2,nr_args);
+#else
+			fprintf(out,"__asm__(\"\\n\\t.global _%s\\n\\t\"\n",name);
+			fprintf(out,"\".global _%s\\n\\t\"\n",name2);
+			fprintf(out,"\"_%s:\\n\\t\"\n",name);
+			fprintf(out,"\"_%s:\\n\\t\"\n",name2);
+#endif
+			fprintf(out,"\t\"mov\t$%d,%%eax\\n\\t\"\n",value);
+			fprintf(out,"\t\"lea\t4(%%esp),%%edx\\n\\t\"\n");
+			fprintf(out,"\t\"int\t$0x2E\\n\\t\"\n");
+			fprintf(out,"\t\"ret\t$%s\\n\\t\");\n\n",nr_args);
 		 
-
-	     value++;
+			/*
+			 * Now write the current system call's name
+			 * in the service table.
+			 */
+			value++;
 	     
-	     if ( first1 == TRUE ) 
-			first1 = FALSE;
-	     else
-			fprintf(out2,",\n");
+			if (first1 == TRUE) 
+			{
+				first1 = FALSE;
+			}
+			else
+			{
+				fprintf(out2,",\n");
+			}
 
-	     fprintf(out2,"\t\t{ %s, (ULONG)%s }",nr_args,name);
-		 
-	  }
-     }
+			fprintf(out2,"\t\t{ %s, (ULONG)%s }",nr_args,name);
+		 	/*
+			 * Now write the NTOSKRNL stub for the
+			 * current system call. ZwXXX does NOT
+			 * alias the corresponding NtXXX call.
+			 */
+			fprintf(out3,"__asm__(\n");
+			fprintf(out3,"\".global _%s@%s\\n\\t\"\n",name2,nr_args);
+			fprintf(out3,"\"_%s@%s:\\n\\t\"\n",name2,nr_args);
+			fprintf(out3,"\t\"mov\t$%d,%%eax\\n\\t\"\n",value);
+			fprintf(out3,"\t\"lea\t4(%%esp),%%edx\\n\\t\"\n");
+			fprintf(out3,"\t\"int\t$0x2E\\n\\t\"\n");
+			fprintf(out3,"\t\"ret\t$%s\\n\\t\");\n\n",nr_args);
+		}
+	}
 
-     fprintf(out2,"\n};\n");
+	fprintf(out2,"\n};\n");
 	 
-   return(0);
+	return(0);
 }
 
-void usage(void)
+void usage(char * argv0)
 {
-   printf("Usage: genntdll sysfuncs.lst outfile.asm outfile.h\n");
+	printf("\
+Usage: %s sysfuncs.lst napi.c napi.h zw.c\n\
+  sysfuncs.lst  system functions database\n\
+  napi.c        NTDLL stubs\n\
+  napi.h        NTOSKRNL service table\n\
+  zw.c          NTOSKRNL Zw stubs\n",
+		argv0
+		);
 }
 
 int main(int argc, char* argv[])
 {
-   FILE* in;
-   FILE* out;
-   FILE *out2;
-   int ret;
+	FILE	* in;	/* System calls database */
+	FILE	* out;	/* NTDLL stubs */
+	FILE	* out2;	/* SERVICE_TABLE */
+	FILE	* out3;	/* NTOSKRNL Zw stubs */
+	int	ret;
    
-   if (argc!=4)
-     {
-	usage();
-	return(1);
-     }
+	if (argc != 5)
+	{
+		usage(argv[0]);
+		return(1);
+	}
    
-   in = fopen(argv[1],"rb");
-   if (in==NULL)
-     {
-	perror("Failed to open input file");
-	return(1);
-     }
+	in = fopen(argv[1],"rb");
+	if (in == NULL)
+	{
+		perror("Failed to open input file (system calls database)");
+		return(1);
+	}
    
-   out = fopen(argv[2],"wb");
-   if (out==NULL)
-     {
-	perror("Failed to open output file");
-	return(1);
-     }
-   out2 = fopen(argv[3],"wb");
-   if (out2==NULL)
-     {
-	perror("Failed to open output file");
-	return(1);
-     }
+	out = fopen(argv[2],"wb");
+	if (out == NULL)
+	{
+		perror("Failed to open output file (NTDLL stubs)");
+		return(1);
+	}
+	out2 = fopen(argv[3],"wb");
+	if (out2 == NULL)
+	{
+		perror("Failed to open output file (NTOSKRNL service table)");
+		return(1);
+	}
+	out3 = fopen(argv[4],"wb");
+	if (out3 == NULL)
+	{
+		perror("Failed to open output file (NTOSKRNL Zw stubs)");
+		return(1);
+	}
+
+	ret = process(in,out,out2,out3);
    
-   ret = process(in,out,out2);
+	fclose(in);
+	fclose(out);
+	fclose(out2);
+	fclose(out3);
    
-   fclose(in);
-   fclose(out);
-   fclose(out2);
-   
-   return(ret);
+	return(ret);
 }
diff --git a/reactos/iface/native/makefile b/reactos/iface/native/makefile
index d31d463c96a..78e356b2736 100644
--- a/reactos/iface/native/makefile
+++ b/reactos/iface/native/makefile
@@ -1,26 +1,43 @@
+# $Id: makefile,v 1.8 1999/06/17 00:10:30 ea Exp $
 #
+# ReactOS Operating System
 #
+# Generate:
+# - genntdll
+# - ntoskrnl.exe service table;
+# - ntoskrnl.exe Zw functions stubs to call Nt functions from kernel mode;
+# - ntdll.dll stubs to call system functions from user mode applications.
 #
+TARGET = genntdll
+SYSTEM_CALLS_DB = sysfuncs.lst
+NTDLL_STUBS = ../../lib/ntdll/napi.c
+KERNEL_SERVICE_TABLE = ../../include/ntdll/napi.h
+KERNEL_ZW_CALLS = ../../ntoskrnl/nt/zw.c
+NAPI_FILES = $(NTDLL_STUBS) $(KERNEL_SERVICE_TABLE) $(KERNEL_ZW_CALLS)
 
-NAPI_FILES = ../../lib/ntdll/napi.c ../../include/ntdll/napi.h
+all: $(TARGET)$(EXE_POSTFIX) $(NAPI_FILES)
 
-all: genntdll$(EXE_POSTFIX) $(NAPI_FILES)
-
-$(NAPI_FILES): sysfuncs.lst genntdll$(EXE_POSTFIX) 
-	genntdll$(EXE_POSTFIX) sysfuncs.lst ../../lib/ntdll/napi.c ../../include/ntdll/napi.h
+$(NAPI_FILES): $(SYSTEM_CALLS_DB) $(TARGET)$(EXE_POSTFIX) 
+	$(TARGET)$(EXE_POSTFIX) \
+		$(SYSTEM_CALLS_DB) \
+		$(NTDLL_STUBS) \
+		$(KERNEL_SERVICE_TABLE) \
+		$(KERNEL_ZW_CALLS)
 
 # (rjj) i removed the following option from line below: -If:\gnu\mingw32\include 
-genntdll$(EXE_POSTFIX): genntdll.c
-	$(NATIVE_CC) -g genntdll.c -o genntdll$(EXE_POSTFIX)	
+$(TARGET)$(EXE_POSTFIX): $(TARGET).c
+	$(NATIVE_CC) -g $(TARGET).c -o $(TARGET)$(EXE_POSTFIX)	
 
 clean:
-	- $(RM) genntdll$(EXE_POSTFIX)
+	- $(RM) $(TARGET)$(EXE_POSTFIX)
 ifeq ($(DOSCLI),yes)
 	- $(RM) ..\..\lib\ntdll\napi.c
 	- $(RM) ..\..\include\ntdll\napi.h
+	- $(RM) ..\..\ntoskrnl\nt\zw.c
 else
-	- $(RM) ../../lib/ntdll/napi.c
-	- $(RM) ../../include/ntdll/napi.h
+	- $(RM) $(NTDLL_STUBS)
+	- $(RM) $(KERNEL_SERVICE_TABLE)
+	- $(RM) $(KERNEL_ZW_CALLS)
 endif
 	
 .PHONY: all clean