From owner-freebsd-bugs  Mon Oct 29  8:10: 7 2001
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Date: Mon, 29 Oct 2001 08:10:02 -0800 (PST)
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Cc: 
From: Tor.Egge@fast.no
Subject: Re: Re[2]: i386/31535: Can't reboot system: Tyan Thunder K7+ Dual AMD Athlon 1.2 MP / FreeBSD 4.4 STABLE or 4.3 RELEASE
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The following reply was made to PR i386/31535; it has been noted by GNATS.

From: Tor.Egge@fast.no
To: ilin@rinet.ru
Cc: freebsd-gnats-submit@FreeBSD.org
Subject: Re: Re[2]: i386/31535: Can't reboot system: Tyan Thunder K7+ Dual AMD Athlon 1.2 MP / FreeBSD 4.4 STABLE or 4.3 RELEASE
Date: Mon, 29 Oct 2001 17:04:38 +0100

 > Hello Tor,
 > 
 > Monday, October 29, 2001, 6:51:11 AM, you wrote:
 > 
 > > The shutdown routine uses memory based syncronization to let the BSP
 > > perform the real reset.  Your problem looks like a livelock, which can
 > > be avoided by flushing the cache after setting the variable used for
 > > syncronization.
 > 
 > Hmm... Problem not fixed.
 
 The AP probably managed to count to 10000000 before the BSP had
 completed printing the message about having grabbed the MP lock.  Thus
 cpu_reset_proxy_active was not updated before the timeout had expired.
 
 The fix for that is to move the printf call to after the wbinvd()
 statement in cpu_reset_proxy().
 
 
 Index: sys/i386/i386/vm_machdep.c
 ===================================================================
 RCS file: /home/ncvs/src/sys/i386/i386/vm_machdep.c,v
 retrieving revision 1.132.2.5
 diff -u -r1.132.2.5 vm_machdep.c
 --- sys/i386/i386/vm_machdep.c	22 Sep 2001 09:21:48 -0000	1.132.2.5
 +++ sys/i386/i386/vm_machdep.c	29 Oct 2001 15:55:23 -0000
 @@ -406,12 +415,14 @@
  	u_int saved_mp_lock;
  
  	cpu_reset_proxy_active = 1;
 +	wbinvd();
  	while (cpu_reset_proxy_active == 1)
  		;	 /* Wait for other cpu to disable interupts */
  	saved_mp_lock = mp_lock;
  	mp_lock = 1;
 -	printf("cpu_reset_proxy: Grabbed mp lock for BSP\n");
  	cpu_reset_proxy_active = 3;
 +	wbinvd();
 +	printf("cpu_reset_proxy: Grabbed mp lock for BSP\n");
  	while (cpu_reset_proxy_active == 3)
  		;	/* Wait for other cpu to enable interrupts */
  	stop_cpus((1<<cpu_reset_proxyid));
 @@ -454,6 +465,7 @@
  			started_cpus = (1<<0);		/* Restart CPU #0 */
  
  			cnt = 0;
 +			wbinvd();
  			while (cpu_reset_proxy_active == 0 && cnt < 10000000)
  				cnt++;	/* Wait for BSP to announce restart */
  			if (cpu_reset_proxy_active == 0)
 @@ -461,6 +473,7 @@
  			__asm __volatile("cli" : : : "memory");
  			cpu_reset_proxy_active = 2;
  			cnt = 0;
 +			wbinvd();
  			while (cpu_reset_proxy_active == 2 && cnt < 10000000)
  				cnt++;	/* Do nothing */
  			if (cpu_reset_proxy_active == 2) {
 @@ -468,6 +481,7 @@
  				cpu_reset_real();	/* XXX: Bogus ? */
  			}
  			cpu_reset_proxy_active = 4;
 +			wbinvd();
  			__asm __volatile("sti" : : : "memory");
  			while (1);
  			/* NOTREACHED */

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