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Date:      Mon, 05 Feb 96 07:45:31 -0600
From:      swise@austin.ibm.com (Jean-Steveau Wise)
To:        freebsd-bugs@freebsd.org
Cc:        swise@austin.ibm.com (Jean-Steveau Wise)
Subject:   Re: ATAPI 4x cdrom hang 
Message-ID:  <9602051345.AA28188@vikings.austin.ibm.com>
In-Reply-To: (Your message of Sun, 04 Feb 96 18:39:31 PST.) <22309.823487971@time.cdrom.com> 

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jkh@time.cdrom.com says:

| > I've enabled the debugger.  I can enter it via ctrl-alt-esc.  However,
| > when I reproduce the problem, I cannot enter the debugger.  Also pings
| > into the machine via an ethernet IF stops after it's hung. Soooo, my
| > guess is that somewhere we're looping with all interrupts disabled.
| > I'll now try and put some breakpoints in the ATAPI driver to understand
| > where it's hanging...
| 
| Yeah, that's about your only recourse, sorry! :-(  Good luck!

I've learned very little about what's happening by breaking in the
various atapi routines...  I also enabled DIAGNOSTIC and no change in
behavior.  I compiled the ATAPI driver with DEBUG and I get a lot of
printf's when the thing takes an interrupt.  The last thing I see is
the driver taking an interrupt, then the system hangs.  THere's nothing
strange about the interrupt as far as I can tell.

Question:  Is it possible that the driver's leaving interrupts disabled?
On AIX we have debug code in the system call routines to jump into the
debugger if we're exiting a system call with either ints disabled or
a kernel lock held.  I cannot tell from the source how to program such
an assertion in FreeBSD.  I guess I could add such assertions to the 
sys call exit and SW interrupt exit?

| > ok and begin booting, but would fail during boot process.  I think the 
| > kernel is assuming the root volume is on controller one/disk one or two?
| 
| No, don't think so..  Is the kernel below cylinder 1024?

Yes.  I've since moved my 2 drives to the first controller, and put the
CDROM on the second, and everything works fine.  I need this system up
and running, so I won't continue debugging this one as it requires
re-installing.  During the boot process, the system displays this
message after probing the busses:

	changing root device to wd1a

Now, even if I install onto wd2a, this message still says wd1a.  At
this point the system complains  that there's no root fs and bails.
However, I think it's just not looking at wd2a even though it just
booted the kernel from there...does this make sense?

Thanx,

Stevo.


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