From: Peter Maydell <peter.maydell@linaro.org>
To: "Emilio G. Cota" <cota@braap.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>
Subject: Re: [Qemu-devel] linux-user crashes on clone(2) when run on ppc host
Date: Thu, 18 Jun 2015 08:42:40 +0100 [thread overview]
Message-ID: <CAFEAcA-Rw+urpNKVfj=k1as+YaT72z+OAU5_gw0HyKsoLoMbaQ@mail.gmail.com> (raw)
In-Reply-To: <20150617213625.GA16082@flamenco>
On 17 June 2015 at 22:36, Emilio G. Cota <cota@braap.org> wrote:
> 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?
None of the code generation data structures are locked at all --
if two threads try to generate code at the same time they'll
tend to clobber each other.
> On x86 hosts linux-user works reliably with multithreaded apps.
No, it doesn't :-) If any multithreaded app happens to run on
any host it is pure fluke.
-- PMM
next prev parent reply other threads:[~2015-06-18 7:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-17 0:52 [Qemu-devel] linux-user crashes on clone(2) when run on ppc host Emilio G. Cota
2015-06-17 8:58 ` Peter Maydell
2015-06-17 21:36 ` Emilio G. Cota
2015-06-18 7:42 ` Peter Maydell [this message]
2015-06-18 14:23 ` Emilio G. Cota
2015-06-18 14:55 ` Peter Maydell
2015-06-18 18:36 ` Emilio G. Cota
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