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Date: Wed, 17 Jun 2015 17:36:25 -0400
From: "Emilio G. Cota" <cota@braap.org>
Message-ID: <20150617213625.GA16082@flamenco>
References: <20150617005222.GA18884@flamenco>
	<CAFEAcA_y0d3T3368Ya9rnvKVTCsHvonnQguGAs=kaDdMS3Gh2w@mail.gmail.com>
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Subject: Re: [Qemu-devel] linux-user crashes on clone(2) when run on ppc host
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Riku Voipio <riku.voipio@iki.fi>, "qemu-ppc@nongnu.org" <qemu-ppc@nongnu.org>, Alexander Graf <agraf@suse.de>, QEMU Developers <qemu-devel@nongnu.org>

On Wed, Jun 17, 2015 at 09:58:27 +0100, Peter Maydell wrote:
> On 17 June 2015 at 01:52, Emilio G. Cota <cota@braap.org> wrote:
> > I'm having trouble running a simple multithreaded program on a PowerPC host machine.
> >
> > The machine I'm using is a ppc VM--I think it's running under KVM (I'm using
> > OVH's RunAbove Power8 service):
> >   admin@adsf:~/qemu$ uname -a
> >   Linux adsf 3.13.0-37-generic #64-Ubuntu SMP Mon Sep 22 21:27:09 UTC 2014 ppc64le ppc64le ppc64le GNU/Linux
> >
> > admin@adsf:~/qemu$ ppc64le-linux-user/qemu-ppc64le foo
> 
> Multithreaded binaries don't work with linux-user; there are a bunch
> of known race conditions involving data structures we don't correctly
> lock or make per-thread.
> 
> This is a long-standing issue; we're hoping we might get to fixing
> it some time this year.

I don't think this is a race because it also breaks when
run on a single core (with taskset -c 0).

What data structures are you referring to? Are they ppc-specific?
On x86 hosts linux-user works reliably with multithreaded apps.
I'd expect any races on common code to show up on x86 as well.

Thanks,

		Emilio