From owner-freebsd-mobile  Wed Jul 17 09:03:55 1996
Return-Path: owner-mobile
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.5/8.7.3) id JAA00512
          for mobile-outgoing; Wed, 17 Jul 1996 09:03:55 -0700 (PDT)
Received: from who.cdrom.com (who.cdrom.com [204.216.27.3])
          by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id JAA00480;
          Wed, 17 Jul 1996 09:03:50 -0700 (PDT)
Received: from zero-gravity.netlab.london.sco.com (zero-gravity.netlab.london.sco.com [150.126.252.16])
          by who.cdrom.com (8.6.12/8.6.11) with ESMTP id IAA23273
          ; Wed, 17 Jul 1996 08:34:41 -0700
Received: (from davided@localhost) by zero-gravity.netlab.london.sco.com (8.7.5/dme/nice-1.1) id QAA00438; Wed, 17 Jul 1996 16:27:10 +0100 (BST)
Date: Wed, 17 Jul 1996 16:27:10 +0100 (BST)
Message-Id: <199607171527.QAA00438@zero-gravity.netlab.london.sco.com>
To: Nate Williams <nate@mt.sri.com>
Cc: mobile@freebsd.org, bde@freebsd.org, davidg@freebsd.org
Subject: re: Possible fix for APM_DSVALUE_BUG
In-Reply-To: <199607161832.MAA25236@rocky.mt.sri.com>
References: <199607161832.MAA25236@rocky.mt.sri.com>
Mime-Version: 1.0 (generated by tm-edit 7.68)
Content-Type: text/plain; charset=US-ASCII
From: dave edmondson <davided@sco.com>
X-Face: "?v.huY]?B[a4C|xid!Tx8TpwOQe6]C(I}h8Vo1z6'9soM_Xvq2f3u::[F~rW>GWj6;IfU,10H;B&1JDE/H8?``q4XH4~!\_z{n3RDmkC;9d!Yx3O7n?9,[CE;TWB!
	F8.e5fc0dJXikU'v1qFVTfptB7xe$y*t#jx4`I44n,ypMQg@.|Z^ycJ:G]{dR~E}_.T1^shwC%T4eRGVu%h+J7lBzb>m20==Q*OPAf^~@6Lj^)rI9Tb*m*L}}HC~{>
	/__Od\I=[|aP6s}B%BhqtE-9uGJ0J3jchjcyJz5fW[i0$RfPv7Zp=!a+0pR
Sender: owner-mobile@freebsd.org
X-Loop: FreeBSD.org
Precedence: bulk

nate, thanks for the fix.  things have improved (in some respects).

with this latest fix my tp760 will now boot, apm 1.1 is detected and
apm mostly works (*).  unfortunately, the ep driver doesn't work with
my 3c589 any more.  with the `standard' pccard.conf card configuration
fails.  setting the interrupt to 10 (or various other values) in
pccard.conf solves this, and the card is recognised and configuration
proceeds.  during configuration, a single page of kernel text gets
filled with zero's.  this happens during the call to dev_attach() from
ep_isa_registerdev() from ep_pccard_init() from allocate_driver().

the page that gets zero'd is always the same - that surrounding the
kdc_npx structure in i386/isa/npx.c.  the instruction that causes it
to happen is a movl which corresponds to:
	kdc->kdc_next->kdc_rlink = &kdc->kdc_next
in dev_attach().  i guess it's always the same page because npx is
always first on my dc_list.

stopping the kernel (using the debugger) before the offending
instruction and writing to the same location myself doesn't cause the
same behaviour.  i presume that something is messing up the page
descriptor for this page and the vm system is demand filling it with
zero's (will it do that whilst i'm single stepping in the debugger ?).

this page being zero filled causes a panic on the next exec, because
npxinit() gets called (and now starts with addb %al, 0(%eax) where
%eax has some completely useless value (0x8zzzzzzz something).

at this point i'm stumped - vm stuff always does have me banging my
head.

as an aside, my usrobotics xj2288 modem works just fine !

* - there are some error messages when i resume after suspend, which
    i'm looking into, but they don't seem to be related to the above
    problem.

once again, thanks for all the work !