Re: [9fans] GUI toolkit for Plan 9

[nigel@9fs.org]

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du -a . | grep ...

panic iunlock can be caused by two things:

	if(l->key == 0)
		print("iunlock: not locked: pc %luX\n", getcallerpc(&l));
	if(!l->isilock)
		print("iunlock of lock: pc %lux, held by %lux\n", getcallerpc(&l), l->pc);

i.e. iunlocking something not locked at all, or iunlocking something
that was locked.

lock = spin lock
ilock = disable interrupts and spin lock

the real interest is the pc printed out, because it tells you where the iunlock()
was called from. You can consult the kernel image to find out where this
is.


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From: Martin C.Atkins <martin@mca-ltd.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] GUI toolkit for Plan 9
Date: Mon, 4 Mar 2002 19:29:54 +0530
Message-ID: <20020304192954.33a0cb67.martin@mca-ltd.com>

On Mon, 4 Mar 2002 10:07:09 GMT "Thomas Bushnell, BSG" <tb+usenet@becket.net> wrote:
> martin@mca-ltd.com (Martin C.Atkins) writes:
> 
> > I'm sorry that I can't remember *any* attribution, but I thought it
> > was "common wisdom/knowledge" that gcc only really worked properly
> > with -O turned on. That the optimiser "optimised away the bugs put in
> > by the code generator". This is going back a few years, so it may be
> > things have "improved"?
> 
> One of the dangerous things about FUD is that people continue to
> repeat it, when it was never true, without attribution except as
> "common wisdom".

That's as may be. But it never occurred to me that this might be FUD
(until you kindly pointed it out). Rather, I thought it was a
curiosity about the way that gcc's code generation worked (and not
*inherently* incorrect, so long as one didn't regard compiling
without -O as "compiling"), and - more importantly - a hint as to how
to avoid unnecessary pain (to me, as a user of gcc, at that time, and
still now).

(After all, I'm still really a Linux lurker. Also, having lost most
of yesterday trying to get Plan 9 to install on a new machine without
destroying it's partition table (I tried 3 times before giving up and
zeroing the disk), I'm not too well disposed to Plan9 right now.
Although to be fair, it's working great now..... - BTW: What *does*
"panic iunlock" mean (I think that was it), apart from "You're
stuffed - go and hit your head on a nearby wall, and then start
over..."? First time I thought it was because I had done something
silly, but the second time I *hadn't* done the silly thing....
Still, at least the good side effect is that I no-longer have Windows
on the machine :-) )

BTW: what's the Plan9 equivalent of Unix's "find . -name ... -print"? 
(always a good fallback for a beginner :-)

Martin
-- 
Martin C. Atkins	martin@mca-ltd.com
Mission Critical Applications Ltd, U.K.