PERFORCE change 54960 for review

[Juli Mallett]

http://perforce.freebsd.org/chv.cgi?CH=54960

Change 54960 by jmallett at jmallett_oingo on 2004/06/14 22:42:18

	Go back to cute AND'ing of bits.  Looks like this may actually be a
	requirement for at least one of my systems, or I'm on crack.

Affected files ...

.. //depot/projects/mips/sys/mips/mips/locore.S#14 edit

Differences ...

==== //depot/projects/mips/sys/mips/mips/locore.S#14 (text+ko) ====

@@ -54,19 +54,27 @@
 GLOBAL(btext)
 ENTRY(start)
 	/*
-	 * t0: Bits to set:
+	 * t0: Bits to preserve if set:
+	 * 	Soft reset
+	 *	Boot exception vectors (firmware-provided)
+	 */
+	li	t0, MIPS_SR_BEV | MIPS_SR_SR
+	/*
+	 * t1: Bits to set explicitly:
 	 *	Kernel mode is 64-bit
 	 *	Enable FPU
 	 */
-	li	t0, MIPS_SR_KX | MIPS_SR_COP_1_BIT
+	li	t1, MIPS_SR_KX | MIPS_SR_COP_1_BIT
 
 	/*
-	 * Read coprocessor 0 status register, and set bits we want to
-	 * explicitly set.
+	 * Read coprocessor 0 status register, clear bits not
+	 * preserved (namely, clearing interrupt bits), and set
+	 * bits we want to explicitly set.
 	 */
-	mfc0	t1, MIPS_COP_0_STATUS
-	or	t1, t0
-	mtc0	t1, MIPS_COP_0_STATUS
+	mfc0	t2, MIPS_COP_0_STATUS
+	and	t2, t0
+	or	t2, t1
+	mtc0	t2, MIPS_COP_0_STATUS
 	COP0_SYNC
 	/* Extra nops for the FPU to spin up. */