If you have an i386 box with APM support which has trouble suspending
more than once, or trouble staying suspended, or other various problems
(not involving error codes once per second or machine resets), try out
this change to apm.c and let me know if it improves your system's
behaviour.

==John

Index: apm.c
Prereq: 1.19
===================================================================
RCS file: /u3/cvsroot/src/sys/arch/i386/i386/apm.c,v
retrieving revision 1.1.1.11
diff -c -r1.1.1.11 apm.c
*** apm.c	1997/01/12 05:00:24	1.1.1.11
--- apm.c	1997/04/10 02:32:59
***************
*** 137,145 ****
  #endif
  STATIC void apm_perror __P((const char *, struct apmregs *, ...))
  	    __kprintf_attribute__((__format__(__printf__,1,3)));
- #if 0
  STATIC void apm_powmgt_enable __P((int));
- #endif
  STATIC void apm_powmgt_engage __P((int, u_int));
  #if 0
  STATIC void apm_devpowmgt_enable __P((int, u_int));
--- 137,143 ----
***************
*** 293,298 ****
--- 291,297 ----
  int apm_suspends = 0;
  int apm_battlow = 0;
  int apm_damn_fool_bios = 0;
+ int apm_op_inprog = 0;
  
  STATIC void
  apm_get_powstate(dev)
***************
*** 321,326 ****
--- 320,329 ----
  
  static int apm_evindex = 0;
  
+ /*
+  * return 0 if the user will notice and handle the event,
+  * return 1 if the kernel driver should do so.
+  */
  STATIC int
  apm_record_event(sc, event_type)
  struct apm_softc *sc;
***************
*** 352,384 ****
  
  	switch(regs->bx) {
  	case APM_USER_STANDBY_REQ:
! 		DPRINTF(("user wants STANDBY--fat chance\n"));
! 		(void) apm_set_powstate(APM_DEV_ALLDEVS, APM_LASTREQ_REJECTED);
! #ifndef APM_NO_STANDBY
  		if (apm_record_event(sc, regs->bx))
  			apm_userstandbys++;
  #endif
  		break;
  	case APM_STANDBY_REQ:
  		DPRINTF(("standby requested\n"));
  		if (apm_standbys || apm_suspends)
  		    DPRINTF(("damn fool BIOS did not wait for answer\n"));
! #ifndef APM_NO_STANDBY
! 		if (apm_record_event(sc, regs->bx)) {
! 			(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 						APM_LASTREQ_INPROG);
  			apm_standbys++;
! 		} else
  #endif
- 			(void) apm_set_powstate(APM_DEV_ALLDEVS,
- 						APM_LASTREQ_REJECTED);
  		break;
  	case APM_USER_SUSPEND_REQ:
! 		DPRINTF(("user wants suspend--fat chance!\n"));
! 		(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 					APM_LASTREQ_REJECTED);
  		if (apm_record_event(sc, regs->bx))
  			apm_suspends++;
  		break;
  	case APM_SUSPEND_REQ:
  		DPRINTF(("suspend requested\n"));
--- 355,396 ----
  
  	switch(regs->bx) {
  	case APM_USER_STANDBY_REQ:
! 	    DPRINTF(("user standby requested\n"));
! #ifdef APM_NO_STANDBY
! 		(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 					APM_LASTREQ_REJECTED);
! 		apm_powmgt_enable(1);	/* in case BIOS hates being spurned */
! #else
  		if (apm_record_event(sc, regs->bx))
  			apm_userstandbys++;
+ 		apm_op_inprog++;
+ 		(void) apm_set_powstate(APM_DEV_ALLDEVS,
+ 					APM_LASTREQ_INPROG);
  #endif
  		break;
  	case APM_STANDBY_REQ:
  		DPRINTF(("standby requested\n"));
  		if (apm_standbys || apm_suspends)
  		    DPRINTF(("damn fool BIOS did not wait for answer\n"));
! #ifdef APM_NO_STANDBY
! 		(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 					APM_LASTREQ_REJECTED);
! 		apm_powmgt_enable(1);	/* in case BIOS hates being spurned */
! #else
! 		if (apm_record_event(sc, regs->bx))
  			apm_standbys++;
! 		apm_op_inprog++;
! 		(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 					APM_LASTREQ_INPROG);
  #endif
  		break;
  	case APM_USER_SUSPEND_REQ:
! 		DPRINTF(("user wants suspend\n"));
  		if (apm_record_event(sc, regs->bx))
  			apm_suspends++;
+ 		apm_op_inprog++;
+ 		(void) apm_set_powstate(APM_DEV_ALLDEVS,
+ 					APM_LASTREQ_INPROG);
  		break;
  	case APM_SUSPEND_REQ:
  		DPRINTF(("suspend requested\n"));
***************
*** 387,399 ****
  			/* just give up the fight */
  			apm_damn_fool_bios = 1;
  		}
! 		if (apm_record_event(sc, regs->bx)) {
! 			(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 						APM_LASTREQ_INPROG);
  			apm_suspends++;
! 		} else
! 			(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 						APM_LASTREQ_REJECTED);
  		break;
  	case APM_POWER_CHANGE:
  		DPRINTF(("power status change\n"));
--- 399,409 ----
  			/* just give up the fight */
  			apm_damn_fool_bios = 1;
  		}
! 		if (apm_record_event(sc, regs->bx))
  			apm_suspends++;
! 		apm_op_inprog++;
! 		(void) apm_set_powstate(APM_DEV_ALLDEVS,
! 					APM_LASTREQ_INPROG);
  		break;
  	case APM_POWER_CHANGE:
  		DPRINTF(("power status change\n"));
***************
*** 409,415 ****
  		apm_record_event(sc, regs->bx);
  		break;
  	case APM_CRIT_RESUME:
! 		DPRINTF(("system resumed without us!\n"));
  		inittodr(time.tv_sec);
  		apm_record_event(sc, regs->bx);
  		break;
--- 419,425 ----
  		apm_record_event(sc, regs->bx);
  		break;
  	case APM_CRIT_RESUME:
! 		DPRINTF(("resume from critical system suspend!\n"));
  		inittodr(time.tv_sec);
  		apm_record_event(sc, regs->bx);
  		break;
***************
*** 452,465 ****
  	struct apmregs regs;
  	struct apm_softc *sc = arg;
  
! 	while (apm_get_event(&regs) == 0 && !apm_damn_fool_bios) {
  		apm_event_handle(sc, &regs);
! 	};
  	if (APM_ERR_CODE(&regs) != APM_ERR_NOEVENTS)
  		apm_perror("get event", &regs);
  	if (apm_suspends) {
  		apm_suspend();
  	} else if (apm_standbys || apm_userstandbys) {
  		apm_standby();
  	}
  	apm_suspends = apm_standbys = apm_battlow = apm_userstandbys = 0;
--- 462,484 ----
  	struct apmregs regs;
  	struct apm_softc *sc = arg;
  
! 	/*
! 	 * tell the BIOS we're working on it, if asked to do a
! 	 * suspend/standby
! 	 */
! 	if (apm_op_inprog)
! 		apm_set_powstate(APM_DEV_ALLDEVS, APM_LASTREQ_INPROG);
! 
! 	while (apm_get_event(&regs) == 0 && !apm_damn_fool_bios)
  		apm_event_handle(sc, &regs);
! 
  	if (APM_ERR_CODE(&regs) != APM_ERR_NOEVENTS)
  		apm_perror("get event", &regs);
  	if (apm_suspends) {
+ 		apm_op_inprog = 0;
  		apm_suspend();
  	} else if (apm_standbys || apm_userstandbys) {
+ 		apm_op_inprog = 0;
  		apm_standby();
  	}
  	apm_suspends = apm_standbys = apm_battlow = apm_userstandbys = 0;
***************
*** 467,486 ****
  	timeout(apm_periodic_check, sc, hz);
  }
  
- #if 0
  STATIC void
  apm_powmgt_enable(onoff)
  int onoff;
  {
  	struct apmregs regs;
! 	regs.bx = apm_minver == 0 ? APM_MGT_ALL : APM_DEV_APM_BIOS;
  	regs.cx = onoff ? APM_MGT_ENABLE : APM_MGT_DISABLE;
  	if (APMCALL(APM_PWR_MGT_ENABLE, &regs) != 0)
! 		apm_perror("power management enable <%s %s>", &regs,
! 			   apm_minver == 0 ? "all" : "apmbios",
  			   onoff ? "enable" : "disable");
  }
- #endif
  
  STATIC void
  apm_powmgt_engage(onoff, dev)
--- 486,502 ----
  	timeout(apm_periodic_check, sc, hz);
  }
  
  STATIC void
  apm_powmgt_enable(onoff)
  int onoff;
  {
  	struct apmregs regs;
! 	regs.bx = apm_minver == 0 ? APM_MGT_ALL : APM_DEV_ALLDEVS;
  	regs.cx = onoff ? APM_MGT_ENABLE : APM_MGT_DISABLE;
  	if (APMCALL(APM_PWR_MGT_ENABLE, &regs) != 0)
! 		apm_perror("power management enable all <%s>", &regs,
  			   onoff ? "enable" : "disable");
  }
  
  STATIC void
  apm_powmgt_engage(onoff, dev)
***************
*** 939,944 ****
--- 955,968 ----
  			 &apminfo.apm_segsel,
  			 apmsc->sc_dev.dv_xname));
  		apm_set_ver(apmsc);
+ 		/*
+ 		 * enable power management if it's disabled.
+ 		 */
+ 		/* XXX some bogus APM BIOSes don't set the disabled bit in
+ 		   the connect state, yet still complain about the functions
+ 		   being disabled when other calls are made.  sigh. */
+ 		if (apminfo.apm_detail & APM_BIOS_PM_DISABLED)
+ 			apm_powmgt_enable(1);
  		/*
  		 * Engage cooperative power mgt (we get to do it)
  		 * on all devices (v1.1).