NetBSD Problem Report #35363

From johan@giantfoo.org  Fri Jan  5 21:52:06 2007
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Date: Fri,  5 Jan 2007 15:52:05 -0600 (CST)
From: johan@giantfoo.org
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To: gnats-bugs@NetBSD.org
Subject: 3.1_STABLE problems on dual nocache 50 MHz SuperSPARC (390Z50)
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>Number:         35363
>Category:       port-sparc
>Synopsis:       MP broken for some 50 MHz SuperSPARC (390Z50) processors on 3.1
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-sparc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jan 05 21:55:00 +0000 2007
>Originator:     Johan A. van Zanten
>Release:        NetBSD 3.1_STABLE
>Organization:
Hail Eris!
>Environment:


System: NetBSD vishnu 3.1_STABLE NetBSD 3.1_STABLE (MANGOLASSI.MP) #0: Sun Nov  5 17:37:17 CST 2006  johan@pangu:/tew/003/src/NetBSD/NetBSD-3/src/sys/arch/sparc/compile/MANGOLASSI.MP sparc

Architecture: sparc
Machine: sparc
>Description:

  When the second processor is activated multi-processor 3.1_STABLE sun4m
systems, NetBSD behaves erratically, with some programs seg faulting. The
system is extremely unstable and not usable, but it does not panic.

 Please see my email to port-sparc:

http://mail-index.netbsd.org/port-sparc/2007/01/02/0000.html

 Confirmation of the problem by Michael-John Turner:

http://mail-index.netbsd.org/port-sparc/2007/01/02/0002.html

Original report:
http://mail-index.netbsd.org/port-sparc/2006/12/29/0004.html

Please note that not all 50 MHz SuperSPARC processors trigger the problem.
I have the same OS building running without problems on a dual "390Z55"
system.  My understanding is that a significant difference between CPUs
identified as "390Z50" and "390Z55" is that the '55 has 1 MB of ecache per
CPU, and the '50 has none.

See: http://mbus.sunhelp.org/modules/index.htm#super

 Also, please note that i had a dual 390Z50 system running NetBSD
2.0.2_STABLE without problems, under significant load (Internet-connected
DNS server and MX, as well as KDC), before i upgraded to 3.1_STABLE.
Michael-John Turner's message above also suggests that the problem may
have been introduced between 2.x and 3.x.

>How-To-Repeat:

  Install a NetBSD 3.1 MP kernel (GENERIC.MP produces the problem) on a
sparc with two 390Z50 50 MHz processors.
  Boot the system multi-user.

>Fix:

  Removing the second CPU eliminates the problem, as does switching to
multiple CPUs of a different type, such as "390Z55" or other, faster SPARC
CPUs, all of which appear to have cache (and a cache controller).

>Unformatted:

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