- Don't set CR0_NE and CR0_MP in npx_probe() as they are already set

  earlier in cpu_setregs().
- If we know this CPU has a FPU via cpuid, then just assume the INT16
  interface and make the npx device quiet to not clutter the dmesg.  This
  is true for all Pentium and later CPUs and even some of the later 486dx
  CPUs.

Reviewed by:	bde
Tested by:	ps
MFC after:	1 week

1 files changed, 21 insertions, 25 deletions

diff --git a/sys/i386/isa/npx.c b/sys/i386/isa/npx.c
index 49309f3..18fc4a7 100644
--- a/sys/i386/isa/npx.c
+++ b/sys/i386/isa/npx.c
@@ -234,10 +234,8 @@ npx_intr(dummy)
 }
 
 /*
- * Probe routine.  Initialize cr0 to give correct behaviour for [f]wait
- * whether the device exists or not (XXX should be elsewhere).  Set flags
- * to tell npxattach() what to do.  Modify device struct if npx doesn't
- * need to use interrupts.  Return 0 if device exists.
+ * Probe routine.  Set flags to tell npxattach() what to do.  Set up an
+ * interrupt handler if npx needs to use interrupts.
  */
 static int
 npx_probe(dev)
@@ -250,6 +248,20 @@ npx_probe(dev)
 	u_short control;
 	u_short status;
 
+	device_set_desc(dev, "math processor");
+
+	/*
+	 * Modern CPUs all have an FPU that uses the INT16 interface
+	 * and provide a simple way to verify that, so handle the
+	 * common case right away.
+	 */
+	if (cpu_feature & CPUID_FPU) {
+		hw_float = npx_exists = 1;
+		npx_ex16 = 1;
+		device_quiet(dev);
+		return (0);
+	}
+
 	save_idt_npxtrap = idt[IDT_MF];
 	setidt(IDT_MF, probetrap, SDT_SYS386TGT, SEL_KPL,
 	    GSEL(GCODE_SEL, SEL_KPL));
@@ -277,24 +289,10 @@ npx_probe(dev)
 	outb(IO_NPX, 0);
 
 	/*
-	 * Prepare to trap all ESC (i.e., NPX) instructions and all WAIT
-	 * instructions.  We must set the CR0_MP bit and use the CR0_TS
-	 * bit to control the trap, because setting the CR0_EM bit does
-	 * not cause WAIT instructions to trap.  It's important to trap
-	 * WAIT instructions - otherwise the "wait" variants of no-wait
-	 * control instructions would degenerate to the "no-wait" variants
-	 * after FP context switches but work correctly otherwise.  It's
-	 * particularly important to trap WAITs when there is no NPX -
-	 * otherwise the "wait" variants would always degenerate.
-	 *
-	 * Try setting CR0_NE to get correct error reporting on 486DX's.
-	 * Setting it should fail or do nothing on lesser processors.
-	 */
-	load_cr0(rcr0() | CR0_MP | CR0_NE);
-	/*
-	 * But don't trap while we're probing.
+	 * Don't trap while we're probing.
 	 */
 	stop_emulating();
+
 	/*
 	 * Finish resetting the coprocessor, if any.  If there is an error
 	 * pending, then we may get a bogus IRQ13, but npx_intr() will handle
@@ -303,8 +301,6 @@ npx_probe(dev)
 	 */
 	fninit();
 
-	device_set_desc(dev, "math processor");
-
 	/*
 	 * Don't use fwait here because it might hang.
 	 * Don't use fnop here because it usually hangs if there is no FPU.
@@ -406,10 +402,10 @@ npx_attach(dev)
 
 	if (npx_irq13)
 		device_printf(dev, "IRQ 13 interface\n");
-	else if (npx_ex16)
-		device_printf(dev, "INT 16 interface\n");
-	else
+	else if (!npx_ex16)
 		device_printf(dev, "WARNING: no FPU!\n");
+	else if (!device_is_quiet(dev) || bootverbose)
+		device_printf(dev, "INT 16 interface\n");
 
 	npxinit(__INITIAL_NPXCW__);