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From: Richard Henderson <rth@twiddle.net>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org, 陳韋任 <chenwj@iis.sinica.edu.tw>
Subject: Re: [Qemu-devel] Multi-threaded user program support?
Date: Fri, 19 Aug 2011 09:19:00 -0700	[thread overview]
Message-ID: <4E4E8CF4.80605@twiddle.net> (raw)
In-Reply-To: <CAFEAcA_u3YHmvwAUN-grbNVCWbgxAjrPb2ZDM8_=o_PMhAGv+g@mail.gmail.com>

On 08/18/2011 08:13 PM, Peter Maydell wrote:
> On 19 August 2011 03:59, 陳韋任 <chenwj@iis.sinica.edu.tw> wrote:
>>> More generally and not x86-specific, there are problems with
>>> the multithreaded user-mode support which I suspect exist because
>>> nobody has ever sat down and worked out a coherent design for it,
>>> including what might need to be thread-local and what locking
>>> is required. So the result is that it mostly works but if you
>>
>>  You mean some QEMU data structures need to be thread-local or lock
>> protected in order to emulate guest multi-threaded program correctly?
> 
> Approximately, yes (the third option being "redesign the data
> structure so it can be sensibly protected"). See
> https://bugs.launchpad.net/qemu/+bug/668799 for discussion of
> one example.

I suspect that to make things tractable for i386, which has so
many LOCKable instructions, that we'll also have to implement
at least a compare-and-swap primitive in TCG.


r~

  reply	other threads:[~2011-08-19 16:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-08-18  2:35 [Qemu-devel] Multi-threaded user program support? 陳韋任
2011-08-18  3:00 ` Peter Maydell
2011-08-19  2:59   ` 陳韋任
2011-08-19  3:13     ` Peter Maydell
2011-08-19 16:19       ` Richard Henderson [this message]
2011-08-20  2:35   ` 陳韋任

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