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vr_idle.S revision 1.6.24.1 
      1 /*	$NetBSD: vr_idle.S,v 1.6.24.1 2002/12/18 05:00:58 gmcgarry Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Digital Equipment Corporation and Ralph Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *	This product includes software developed by the University of
     21  *	California, Berkeley and its contributors.
     22  * 4. Neither the name of the University nor the names of its contributors
     23  *    may be used to endorse or promote products derived from this software
     24  *    without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     36  * SUCH DAMAGE.
     37  *
     38  * Copyright (C) 1989 Digital Equipment Corporation.
     39  * Permission to use, copy, modify, and distribute this software and
     40  * its documentation for any purpose and without fee is hereby granted,
     41  * provided that the above copyright notice appears in all copies.
     42  * Digital Equipment Corporation makes no representations about the
     43  * suitability of this software for any purpose.  It is provided "as is"
     44  * without express or implied warranty.
     45  *
     46  */
     47 
     48 #include <mips/asm.h>
     49 #include <mips/cpuregs.h>
     50 #include <hpcmips/vr/vr_asm.h>
     51 
     52 #include "opt_lockdebug.h"
     53 
     54 #include "assym.h"
     55 
     56 	.set	noreorder
     57 
     58 /*
     59  * When no processes are on the runq, cpu_switch branches to idle
     60  * to wait for something to come ready.
     61  * Note: this is really a part of cpu_switch() but defined here for kernel
     62  * profiling.
     63  */
     64 NESTED(vr_idle, CALLFRAME_SIZ, ra)
     65 	.mask	0x80000000, -4
     66 	subu	sp, sp, CALLFRAME_SIZ
     67 	sw	ra, CALLFRAME_RA(sp)
     68 	nop
     69 1:
     70 	lw	t0, _C_LABEL(sched_whichqs)	# look for non-empty queue
     71 	bne	t0, zero, 2f
     72 	nop
     73 	.word	VR_OPCODE_STANDBY
     74 	nop
     75 	nop
     76 	nop
     77 	nop
     78 	bne	t0, zero, 2f
     79 	nop
     80 
     81 	/* Try to zero some free pages. */
     82 	lw	t0, _C_LABEL(uvm) + UVM_PAGE_IDLE_ZERO
     83 	nop
     84 	beq	t0, zero, 1b
     85 	nop
     86 	la	ra, 1b
     87 	j	_C_LABEL(uvm_pageidlezero)
     88 	nop
     89 2:
     90 	lw	ra, CALLFRAME_RA(sp)
     91 	nop
     92 	j	ra
     93 	addu	sp, sp, CALLFRAME_SIZ
     94 END(vr_idle)
     95