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Date: Sun, 27 Sep 2009 15:13:12 +0100
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] linux-user NPTL problem with signals
Message-ID: <20090927141312.GB28368@shareable.org>
References: <4ABA9868.8070707@mlbassoc.com> <4ABB87A9.9060706@mlbassoc.com>
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To: Gary Thomas <gary@mlbassoc.com>
Cc: qemu-devel@nongnu.org

Gary Thomas wrote:
> On 09/23/2009 03:51 PM, Gary Thomas wrote:
> >I'm running a multi-threaded program (linux-user on i386).  I
> >have a problem with signals; when one arrives, the running
> >thread abruptly changes :-(
> >
> >Anyone have any ideas about this?
> >
> 
> I've tracked this down to the fact that there should be a
> unique value for the GS segment register (at least) per thread.
> This doesn't seem to be the case and when a signal is dispatched,
> the GS segment register is updated with [probably] the most recent
> value created by a new thread, not the running thread.

Nasty.  NPTL is not the only software which depends on the segment
registers keeping their correct values.  Wine, DOSemu among others
depend on all the segment registers.

-- Jamie