Failure to dlopen libgomp due to static TLS data

H.J. Lu hjl.tools@gmail.com
Thu Feb 12 16:56:00 GMT 2015


On Thu, Feb 12, 2015 at 8:11 AM, Jakub Jelinek <jakub@redhat.com> wrote:
> On Thu, Feb 12, 2015 at 11:09:59AM -0500, Rich Felker wrote:
>> On Thu, Feb 12, 2015 at 04:18:57PM +0100, Ulrich Weigand wrote:
>> > Hello,
>> >
>> > we're running into a problem related to use of initial-exec access to
>> > TLS variables in dynamically-loaded libraries.  Now, in general, this
>> > is actually not supported.  However, there seems to an "inofficial"
>> > extension that allows selected system libraries to use small amounts
>> > of static TLS space to allow critical variables to be defined to use
>> > the initial-exec model even in dynamically-loaded libraries.
>>
>> This usage is supposed to be deprecated. Why isn't libgomp using
>> TLSDESC/gnu2 model?
>
> Because it is significantly slower.

And TLSDESC/gnu2 model isn't implemented for x32.
There are no tests for TLSDESC/gnu2 model in glibc.
I have no ideas if it works in glibc master on x86-32 or
x86-64 today.


-- 
H.J.



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