Index: sys/i386/include/frame.h
===================================================================
--- sys/i386/include/frame.h
+++ sys/i386/include/frame.h
@@ -1,14 +1,44 @@
 /*-
- * This file is in the public domain.
+ * Copyright (c) 2003 Peter Wemm.
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * William Jolitz.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
  */
-/* $FreeBSD$ */
 
-#include <x86/frame.h>
+#ifndef _I386_FRAME_H_
+#define	_i386_FRAME_H_
 
-#ifndef __I386_FRAME_H__
-#define	__i386_FRAME_H__
+#include <x86/frame.h>
 
 #define	CS_SECURE(cs)		(ISPL(cs) == SEL_UPL)
 #define	EFL_SECURE(ef, oef)	((((ef) ^ (oef)) & ~PSL_USERCHANGE) == 0)
 
-#endif
+#endif	/* _I386_FRAME_H_ */
Index: sys/i386/isa/npx.c
===================================================================
--- sys/i386/isa/npx.c
+++ sys/i386/isa/npx.c
@@ -1173,16 +1173,20 @@
 	/* FPU control/status */
 	penv_87->en_cw = penv_xmm->en_cw;
 	penv_87->en_sw = penv_xmm->en_sw;
-	penv_87->en_tw = penv_xmm->en_tw;
 	penv_87->en_fip = penv_xmm->en_fip;
 	penv_87->en_fcs = penv_xmm->en_fcs;
 	penv_87->en_opcode = penv_xmm->en_opcode;
 	penv_87->en_foo = penv_xmm->en_foo;
 	penv_87->en_fos = penv_xmm->en_fos;
 
-	/* FPU registers */
-	for (i = 0; i < 8; ++i)
+	/* FPU registers and tags */
+	penv_87->en_tw = 0xffff;
+	for (i = 0; i < 8; ++i) {
 		sv_87->sv_ac[i] = sv_xmm->sv_fp[i].fp_acc;
+		if ((penv_xmm->en_tw & (1 << i)) != 0)
+			/* zero and special are set as valid */
+			penv_87->en_tw &= ~(3 << i);
+	}
 }
 
 void
@@ -1206,16 +1210,19 @@
 	/* FPU control/status */
 	penv_xmm->en_cw = penv_87->en_cw;
 	penv_xmm->en_sw = penv_87->en_sw;
-	penv_xmm->en_tw = penv_87->en_tw;
 	penv_xmm->en_fip = penv_87->en_fip;
 	penv_xmm->en_fcs = penv_87->en_fcs;
 	penv_xmm->en_opcode = penv_87->en_opcode;
 	penv_xmm->en_foo = penv_87->en_foo;
 	penv_xmm->en_fos = penv_87->en_fos;
 
-	/* FPU registers */
-	for (i = 0; i < 8; ++i)
+	/* FPU registers and tags */
+	penv_xmm->en_tw = 0;
+	for (i = 0; i < 8; ++i) {
 		sv_xmm->sv_fp[i].fp_acc = sv_87->sv_ac[i];
+		if ((penv_87->en_tw && (3 << i)) != (3 << i))
+		    penv_xmm->en_tw |= 1 << i;
+	}
 }
 #endif /* CPU_ENABLE_SSE */