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From: Giorgos Keramidas <keramida@freebsd.org>
To: "Peter Wemm" <peter@wemm.org>, "Garrett Cooper" <yanefbsd@gmail.com>
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Date: Sun, 30 Nov 2008 16:08:49 +0200
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	(Peter Wemm's message of "Fri, 28 Nov 2008 20:47:00 -0800")
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Cc: freebsd-current@freebsd.org
Subject: Re: tty problems in recent head?
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On Fri, 28 Nov 2008 20:47:00 -0800, "Peter Wemm" <peter@wemm.org> wrote:
>> The xterm processes that get stuck seem to be spinning near line 1854 of
>> sched_ule.c.  Running `info threads' on a live kernel after xterm starts
>> spinning on a CPU shows:

After a bit of help from kib@ and ed@ this seems to be wrong.  The xterm
processes were spinning in userspace, calling ioctl(fd, FIONREAD, ...).

On Sat, 29 Nov 2008 16:02:03 -0800, "Garrett Cooper" <yanefbsd@gmail.com> wrote:
>     Might be another compiler issue. There's an issue with
> -fstrict-aliasing (at least) on all versions of g++ up to 4.2.3:
> <http://lists.copyleft.no/pipermail/pyrex/2007-November/003071.html>.
>     Are there some compiler warnings when compiling kernel / screen?
> Also, have you tried with just COPTFLAGS disabled?

Today I managed to reproduce this with a kernel that doesn't use
optimizations at all, so fortunately this is not a compiler bug :)

I'm testing a patch by Ed Schouten to see if it fixes this, and I will
post more details after a day or so of running with the patch.