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Re: Help debugging a dll issue

On 5/21/2016 9:45 PM, Renà Berber wrote:
On 5/21/2016 6:30 PM, Eliot Moss wrote:

I used binary search, eliminating .o files from the .dll on the thought
that it was either a particular .o file that was leading to a problem,
or possibly the overall size (this is a huge link!).  I found that a .dll
with 58725 section 1 symbols (as reported by objdump -t) works, and one
with 66675 section one symbols fails.  So it appears to be a size issue.

That's telling, since USHRT_MAX (65535) may be the limit, then somewhere
there is the use of a variable of that type (unsigned short int,
uint16_t), which may be part of some specification (i.e. the format of

Supporting that is: which

"65536 symbols. This is the limit that Windows DLLs can handle (the
source of the limitation is that they use 16-bit integers to represent

and also point to an interesting bug report (5 years old):

No answers, but at least an explanation.

Why the maintainers did not fix this, I don't know -- would have saved
me a week of effort tacking things down!

The solution was to use __declspec(dllexport), sparingly, so that only
a few symbols would be exported, and to drop --export-all-symbols. (How
did that work before?  Was the system a lot smaller?)  Supposedly
__attribute__((dllexport)) also works, though I did not try it -- using
__declspec was more in line with code for Windows native C compilers.

At least this thread may help someone in the future!

Regards -- Eliot

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