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Date: Mon, 30 Sep 1996 04:40:07 +0300 (EET DST)
From: Heikki Suonsivu <hsu@clinet.fi>
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Subject: kern/1692: Page fault while in kernel modem fatal trap 12 (double panic)
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>Number:         1692
>Category:       kern
>Synopsis:       Page fault while in kernel modem fatal trap 12 (double panic)
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Sep 29 18:50:01 PDT 1996
>Last-Modified:
>Originator:     Heikki Suonsivu
>Organization:
Clinet, Espoo, Finland
>Release:        FreeBSD 2.2-CURRENT i386
>Environment:

	Several systems used as terminal/modem servers.  These are
	connected to modems (V34), using cyclades serial boards.
	Hardware varies, 486-100/120, VLB or PCI, or Pentium 90 (Asustek MB).

	The machines only run pppd or rlogin and gated for routing.

>Description:

	Systems panic and often lock up with

	Page fault while in kernel mode

	fatal trap 12

	these are almost always double panics (probably always, but
	we never get a crash dump so we do not really know).

	Problems increase with the number of modems, but this is not a
	clear rule; sometimes machines with less than 16 modems are
	unstable.

	We do not see this with machines which serve leased lines with
	exactly the same configuration, so this probably has something
	to do with modems, either with lines going up and down, or
	modem flow control (leased lines are usually with no flow control).

	This problem has been there for ages, from 2.1 days, probably it
	has always existed.  I think I have filed this before, but could
	not find a reference, so I assume if I did it got lost.

>How-To-Repeat:

	Build FreeBSD based terminal/modem server with cyclades boards
	and stack up to 32 modems into it.

>Fix:
	


>Audit-Trail:
>Unformatted: