diff --git a/sys/amd64/amd64/critical.c b/sys/amd64/amd64/critical.c
index 4a983e413d36..de91426fde4c 100644
--- a/sys/amd64/amd64/critical.c
+++ b/sys/amd64/amd64/critical.c
@@ -33,16 +33,6 @@
 
 void i386_unpend(void);		/* NOTE: not static, called from assembly */
 
-/*
- * Instrument our ability to run critical sections with interrupts
- * enabled.  Default is 1 (enabled).  The value can be changed on the
- * fly, at any time.  If set to 0 the original interrupt disablement
- * will be used for critical sections.
- */
-int critical_mode = 1;
-SYSCTL_INT(_debug, OID_AUTO, critical_mode,
-	CTLFLAG_RW, &critical_mode, 0, "");
-
 /*
  * cpu_unpend() -	called from critical_exit() inline after quick
  *			interrupt-pending check.
@@ -66,8 +56,8 @@ cpu_unpend(void)
 /*
  * cpu_critical_fork_exit() - cleanup after fork
  *
- *	For i386 we do not have to do anything, td_critnest and
- *	td_savecrit are handled by the fork trampoline code.
+ *	For i386 we do not have to do anything, td_critnest is
+ *	handled by the fork trampoline code.
  */
 void
 cpu_critical_fork_exit(void)
@@ -77,16 +67,12 @@ cpu_critical_fork_exit(void)
 /*
  * cpu_thread_link() - thread linkup, initialize machine-dependant fields
  *
- *	(copy code originally in kern/kern_proc.c).  XXX we actually
- *	don't have to initialize this field but it's probably a good
- *	idea for the moment for debugging's sake.  The field is only
- *	valid when td_critnest is non-zero.
+ *	There are currently no machine-dependant fields that require 
+ *	initialization.
  */
 void
 cpu_thread_link(struct thread *td)
 {
-
-	td->td_md.md_savecrit = 0;
 }
 
 /*
diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S
index 537382a7a718..039ca98b5a31 100644
--- a/sys/amd64/amd64/exception.S
+++ b/sys/amd64/amd64/exception.S
@@ -225,23 +225,7 @@ ENTRY(fork_trampoline)
 	pushl	%esi			/* function */
 	movl    PCPU(CURTHREAD),%ebx	/* setup critnest */
 	movl	$1,TD_CRITNEST(%ebx)
-	/*
-	 * Initialize md_savecrit based on critical_mode.  If critical_mode
-	 * is enabled (new/1) savecrit is basically not used but must
-	 * be initialized to -1 so we know it isn't used in 
-	 * cpu_critical_exit().  If critical_mode is disabled (old/0)
-	 * the eflags to restore must be saved in md_savecrit.
-	 */
-	cmpl	$0,critical_mode
-	jne	1f
-	pushfl
-	popl	TD_MD+MD_SAVECRIT(%ebx)
-	orl	$PSL_I,TD_MD+MD_SAVECRIT(%ebx)
-	jmp	2f
-1:
-	movl	$-1,TD_MD+MD_SAVECRIT(%ebx)
 	sti				/* enable interrupts */
-2:
 	call	fork_exit
 	addl	$12,%esp
 	/* cut from syscall */
diff --git a/sys/amd64/amd64/exception.s b/sys/amd64/amd64/exception.s
index 537382a7a718..039ca98b5a31 100644
--- a/sys/amd64/amd64/exception.s
+++ b/sys/amd64/amd64/exception.s
@@ -225,23 +225,7 @@ ENTRY(fork_trampoline)
 	pushl	%esi			/* function */
 	movl    PCPU(CURTHREAD),%ebx	/* setup critnest */
 	movl	$1,TD_CRITNEST(%ebx)
-	/*
-	 * Initialize md_savecrit based on critical_mode.  If critical_mode
-	 * is enabled (new/1) savecrit is basically not used but must
-	 * be initialized to -1 so we know it isn't used in 
-	 * cpu_critical_exit().  If critical_mode is disabled (old/0)
-	 * the eflags to restore must be saved in md_savecrit.
-	 */
-	cmpl	$0,critical_mode
-	jne	1f
-	pushfl
-	popl	TD_MD+MD_SAVECRIT(%ebx)
-	orl	$PSL_I,TD_MD+MD_SAVECRIT(%ebx)
-	jmp	2f
-1:
-	movl	$-1,TD_MD+MD_SAVECRIT(%ebx)
 	sti				/* enable interrupts */
-2:
 	call	fork_exit
 	addl	$12,%esp
 	/* cut from syscall */
diff --git a/sys/amd64/amd64/genassym.c b/sys/amd64/amd64/genassym.c
index dcc188080d3a..a26b5dccec73 100644
--- a/sys/amd64/amd64/genassym.c
+++ b/sys/amd64/amd64/genassym.c
@@ -94,7 +94,6 @@ ASSYM(TD_MD, offsetof(struct thread, td_md));
 
 ASSYM(P_MD, offsetof(struct proc, p_md));
 ASSYM(MD_LDT, offsetof(struct mdproc, md_ldt));
-ASSYM(MD_SAVECRIT, offsetof(struct mdthread, md_savecrit));
 
 ASSYM(KE_FLAGS, offsetof(struct kse, ke_flags));
 
diff --git a/sys/amd64/include/critical.h b/sys/amd64/include/critical.h
index 6d142921927e..7cc7ff2b26cb 100644
--- a/sys/amd64/include/critical.h
+++ b/sys/amd64/include/critical.h
@@ -20,8 +20,6 @@
 
 __BEGIN_DECLS
 
-extern int critical_mode;
-
 /*
  * Prototypes - see <arch>/<arch>/critical.c
  */
@@ -37,22 +35,11 @@ void cpu_thread_link(struct thread *td);
  *	This routine is called from critical_enter() on the 0->1 transition
  *	of td_critnest, prior to it being incremented to 1.
  *
- *	If old-style critical section handling (critical_mode == 0), we
- *	disable interrupts. 
- *
- *	If new-style critical section handling (criticla_mode != 0), we
- *	do not have to do anything.  However, as a side effect any
- *	interrupts occuring while td_critnest is non-zero will be
- *	deferred.
+ *	If new-style critical section handling we do not have to do anything.
+ *	However, as a side effect any interrupts occuring while td_critnest
+ *	is non-zero will be deferred.
  */
-static __inline void
-cpu_critical_enter(void)
-{
-	if (critical_mode == 0) {
-		struct thread *td = curthread;
-		td->td_md.md_savecrit = intr_disable();
-	}
-}
+#define cpu_critical_enter()
 
 /*
  *	cpu_critical_exit:
@@ -61,41 +48,26 @@ cpu_critical_enter(void)
  *	of td_critnest, after it has been decremented to 0.  We are
  *	exiting the last critical section.
  *
- *	If td_critnest is -1 this is the 'new' critical_enter()/exit()
- *	code (the default critical_mode=1) and we do not have to do 
- *	anything unless PCPU_GET(int_pending) is non-zero. 
- *
  *	Note that the td->critnest (1->0) transition interrupt race against
  *	our int_pending/unpend() check below is handled by the interrupt
  *	code for us, so we do not have to do anything fancy.
- *
- *	Otherwise td_critnest contains the saved hardware interrupt state
- *	and will be restored.  Since interrupts were hard-disabled there
- *	will be no pending interrupts to dispatch (the 'original' code).
  */
 static __inline void
 cpu_critical_exit(void)
 {
-	struct thread *td = curthread;
-
-	if (td->td_md.md_savecrit != (register_t)-1) {
-		intr_restore(td->td_md.md_savecrit);
-		td->td_md.md_savecrit = (register_t)-1;
-	} else {
-		/*
-		 * We may have to schedule pending interrupts.  Create
-		 * conditions similar to an interrupt context and call
-		 * unpend().
-		 *
-		 * note: we do this even if we are in an interrupt
-		 * nesting level.  Deep nesting is protected by
-		 * critical_*() and if we conditionalized it then we
-		 * would have to check int_pending again whenever
-		 * we decrement td_intr_nesting_level to 0.
-		 */
-		if (PCPU_GET(int_pending))
-			cpu_unpend();
-	}
+	/*
+	 * We may have to schedule pending interrupts.  Create
+	 * conditions similar to an interrupt context and call
+	 * unpend().
+	 *
+	 * note: we do this even if we are in an interrupt
+	 * nesting level.  Deep nesting is protected by
+	 * critical_*() and if we conditionalized it then we
+	 * would have to check int_pending again whenever
+	 * we decrement td_intr_nesting_level to 0.
+	 */
+	if (PCPU_GET(int_pending))
+		cpu_unpend();
 }
 
 #else /* !__GNUC__ */
diff --git a/sys/amd64/include/proc.h b/sys/amd64/include/proc.h
index d7d5ef73acff..f011b5c37149 100644
--- a/sys/amd64/include/proc.h
+++ b/sys/amd64/include/proc.h
@@ -51,7 +51,6 @@ struct proc_ldt {
  * Machine-dependent part of the proc structure for i386.
  */
 struct mdthread {
-	register_t md_savecrit;
 };
 
 struct mdproc {
diff --git a/sys/i386/i386/critical.c b/sys/i386/i386/critical.c
index 4a983e413d36..de91426fde4c 100644
--- a/sys/i386/i386/critical.c
+++ b/sys/i386/i386/critical.c
@@ -33,16 +33,6 @@
 
 void i386_unpend(void);		/* NOTE: not static, called from assembly */
 
-/*
- * Instrument our ability to run critical sections with interrupts
- * enabled.  Default is 1 (enabled).  The value can be changed on the
- * fly, at any time.  If set to 0 the original interrupt disablement
- * will be used for critical sections.
- */
-int critical_mode = 1;
-SYSCTL_INT(_debug, OID_AUTO, critical_mode,
-	CTLFLAG_RW, &critical_mode, 0, "");
-
 /*
  * cpu_unpend() -	called from critical_exit() inline after quick
  *			interrupt-pending check.
@@ -66,8 +56,8 @@ cpu_unpend(void)
 /*
  * cpu_critical_fork_exit() - cleanup after fork
  *
- *	For i386 we do not have to do anything, td_critnest and
- *	td_savecrit are handled by the fork trampoline code.
+ *	For i386 we do not have to do anything, td_critnest is
+ *	handled by the fork trampoline code.
  */
 void
 cpu_critical_fork_exit(void)
@@ -77,16 +67,12 @@ cpu_critical_fork_exit(void)
 /*
  * cpu_thread_link() - thread linkup, initialize machine-dependant fields
  *
- *	(copy code originally in kern/kern_proc.c).  XXX we actually
- *	don't have to initialize this field but it's probably a good
- *	idea for the moment for debugging's sake.  The field is only
- *	valid when td_critnest is non-zero.
+ *	There are currently no machine-dependant fields that require 
+ *	initialization.
  */
 void
 cpu_thread_link(struct thread *td)
 {
-
-	td->td_md.md_savecrit = 0;
 }
 
 /*
diff --git a/sys/i386/i386/exception.s b/sys/i386/i386/exception.s
index 537382a7a718..039ca98b5a31 100644
--- a/sys/i386/i386/exception.s
+++ b/sys/i386/i386/exception.s
@@ -225,23 +225,7 @@ ENTRY(fork_trampoline)
 	pushl	%esi			/* function */
 	movl    PCPU(CURTHREAD),%ebx	/* setup critnest */
 	movl	$1,TD_CRITNEST(%ebx)
-	/*
-	 * Initialize md_savecrit based on critical_mode.  If critical_mode
-	 * is enabled (new/1) savecrit is basically not used but must
-	 * be initialized to -1 so we know it isn't used in 
-	 * cpu_critical_exit().  If critical_mode is disabled (old/0)
-	 * the eflags to restore must be saved in md_savecrit.
-	 */
-	cmpl	$0,critical_mode
-	jne	1f
-	pushfl
-	popl	TD_MD+MD_SAVECRIT(%ebx)
-	orl	$PSL_I,TD_MD+MD_SAVECRIT(%ebx)
-	jmp	2f
-1:
-	movl	$-1,TD_MD+MD_SAVECRIT(%ebx)
 	sti				/* enable interrupts */
-2:
 	call	fork_exit
 	addl	$12,%esp
 	/* cut from syscall */
diff --git a/sys/i386/i386/genassym.c b/sys/i386/i386/genassym.c
index dcc188080d3a..a26b5dccec73 100644
--- a/sys/i386/i386/genassym.c
+++ b/sys/i386/i386/genassym.c
@@ -94,7 +94,6 @@ ASSYM(TD_MD, offsetof(struct thread, td_md));
 
 ASSYM(P_MD, offsetof(struct proc, p_md));
 ASSYM(MD_LDT, offsetof(struct mdproc, md_ldt));
-ASSYM(MD_SAVECRIT, offsetof(struct mdthread, md_savecrit));
 
 ASSYM(KE_FLAGS, offsetof(struct kse, ke_flags));
 
diff --git a/sys/i386/include/critical.h b/sys/i386/include/critical.h
index 6d142921927e..7cc7ff2b26cb 100644
--- a/sys/i386/include/critical.h
+++ b/sys/i386/include/critical.h
@@ -20,8 +20,6 @@
 
 __BEGIN_DECLS
 
-extern int critical_mode;
-
 /*
  * Prototypes - see <arch>/<arch>/critical.c
  */
@@ -37,22 +35,11 @@ void cpu_thread_link(struct thread *td);
  *	This routine is called from critical_enter() on the 0->1 transition
  *	of td_critnest, prior to it being incremented to 1.
  *
- *	If old-style critical section handling (critical_mode == 0), we
- *	disable interrupts. 
- *
- *	If new-style critical section handling (criticla_mode != 0), we
- *	do not have to do anything.  However, as a side effect any
- *	interrupts occuring while td_critnest is non-zero will be
- *	deferred.
+ *	If new-style critical section handling we do not have to do anything.
+ *	However, as a side effect any interrupts occuring while td_critnest
+ *	is non-zero will be deferred.
  */
-static __inline void
-cpu_critical_enter(void)
-{
-	if (critical_mode == 0) {
-		struct thread *td = curthread;
-		td->td_md.md_savecrit = intr_disable();
-	}
-}
+#define cpu_critical_enter()
 
 /*
  *	cpu_critical_exit:
@@ -61,41 +48,26 @@ cpu_critical_enter(void)
  *	of td_critnest, after it has been decremented to 0.  We are
  *	exiting the last critical section.
  *
- *	If td_critnest is -1 this is the 'new' critical_enter()/exit()
- *	code (the default critical_mode=1) and we do not have to do 
- *	anything unless PCPU_GET(int_pending) is non-zero. 
- *
  *	Note that the td->critnest (1->0) transition interrupt race against
  *	our int_pending/unpend() check below is handled by the interrupt
  *	code for us, so we do not have to do anything fancy.
- *
- *	Otherwise td_critnest contains the saved hardware interrupt state
- *	and will be restored.  Since interrupts were hard-disabled there
- *	will be no pending interrupts to dispatch (the 'original' code).
  */
 static __inline void
 cpu_critical_exit(void)
 {
-	struct thread *td = curthread;
-
-	if (td->td_md.md_savecrit != (register_t)-1) {
-		intr_restore(td->td_md.md_savecrit);
-		td->td_md.md_savecrit = (register_t)-1;
-	} else {
-		/*
-		 * We may have to schedule pending interrupts.  Create
-		 * conditions similar to an interrupt context and call
-		 * unpend().
-		 *
-		 * note: we do this even if we are in an interrupt
-		 * nesting level.  Deep nesting is protected by
-		 * critical_*() and if we conditionalized it then we
-		 * would have to check int_pending again whenever
-		 * we decrement td_intr_nesting_level to 0.
-		 */
-		if (PCPU_GET(int_pending))
-			cpu_unpend();
-	}
+	/*
+	 * We may have to schedule pending interrupts.  Create
+	 * conditions similar to an interrupt context and call
+	 * unpend().
+	 *
+	 * note: we do this even if we are in an interrupt
+	 * nesting level.  Deep nesting is protected by
+	 * critical_*() and if we conditionalized it then we
+	 * would have to check int_pending again whenever
+	 * we decrement td_intr_nesting_level to 0.
+	 */
+	if (PCPU_GET(int_pending))
+		cpu_unpend();
 }
 
 #else /* !__GNUC__ */
diff --git a/sys/i386/include/proc.h b/sys/i386/include/proc.h
index d7d5ef73acff..f011b5c37149 100644
--- a/sys/i386/include/proc.h
+++ b/sys/i386/include/proc.h
@@ -51,7 +51,6 @@ struct proc_ldt {
  * Machine-dependent part of the proc structure for i386.
  */
 struct mdthread {
-	register_t md_savecrit;
 };
 
 struct mdproc {