From: Christopher Faylor <cgf-use-the-mailinglist-please@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: limitations of TLS using GCC's __thread keyword and Cygwin
Date: Tue, 04 Sep 2012 21:51:00 -0000 [thread overview]
Message-ID: <20120904215129.GA30731@ednor.casa.cgf.cx> (raw)
In-Reply-To: <50466981.70005@gmail.com>
On Tue, Sep 04, 2012 at 10:50:09PM +0200, V??clav Zeman wrote:
>On 09/04/2012 04:39 PM, Ryan Johnson wrote:
>> On 04/09/2012 8:58 AM, V??clav Zeman wrote:
>>> Hi.
>>>
>>> I am am porting a library that can use the __thread keyword in its
>>> internals to provide thread local storage. Now, with MSVC there is a
>>> limitation on pre-Vista Windows (see [1]) that DLLs using
>>> __declspec(thread) (MSVC equivalent of GCC's __thread) cannot be
>>> loaded using LoadLibrary() because pre-Vista Windows allocate the TLS
>>> declared that way only on process startup. Vista and later Windows do
>>> not seem to have the limitation. Since Cygwin officially still
>>> supports at least Windows XP, I want to provide a library that works
>>> there as well.
>>>
>>> Does Cygwin's GCC and its TLS emulation work around this problem? IOW,
>>> are Cygwin DLLs using TLS declared using __thread keyword safe to be
>>> loaded using LoadLibrary()/dlopen() or are they not safe to be loaded
>>> that way?
>>>
>>> [1] http://msdn.microsoft.com/en-us/library/2s9wt68x.aspx
>>>
>> I suspect it's not a problem, but if I were you I'd write a simple
>> test program to see. Unfortunately, TLS in general seems broken on my
>> machine when I tried it, but that might be due to my home-brew gcc
>> being configured wrong or something.
>I would have done that already but I do not have any Windows XP machine
>to try this on.
I don't believe that __thread is implemented on Cygwin.
cgf
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next prev parent reply other threads:[~2012-09-04 21:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-04 12:58 Václav Zeman
2012-09-04 14:40 ` Ryan Johnson
2012-09-04 20:50 ` Václav Zeman
2012-09-04 21:51 ` Christopher Faylor [this message]
2012-09-05 9:09 ` Václav Zeman
2012-09-05 14:04 ` Ryan Johnson
2012-09-05 19:55 ` Václav Zeman
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