[fpc-pascal] linking and using dynamic libraries on amd64

[Marc Santhoff]

On Do, 2015-02-12 at 00:42 +0100, Marc Santhoff wrote:
> Hi,
> 
> when I try to run a program that dynamically links an external .so
> library it throws a SIGSEGV error at startup. That seems to happen while
> loading the library before any code of mine is exeuted.
> 
> The library is pulled into it by a header translation from C to Pascal.
> The functions are declared "...; stdcall; external libname name xxx'.
> This way it worked on i386.
> 
> When the error occurs the ASM window pops up, which is not very helpful
> for me.
> 
> There may be a minor change in the lib source itself, but compiling the
> header and linking works OK. I have no idea how to check besides getting
> the older versions source and try again. Will try if nothing else is
> fishy.

I did test the old library and the error is the same.

GDB tells me it happens when starting at BEGIN and running the init function
of the library. That function does not have any arguments, I'm assuming
"something else" then ...

> My questions:
> 
> Is there any difference in declaring external functions between 32 and
> 64 bit mode?
> 
> How can I debug what is happening? Will compiling the library having an
> external debug file work when debugging from Lazarus?
> 
> Any hints for diagnosing what's going wrong are very welcome.
> 
> 
> 
> Some data points:
> fpc 2.6.2 x86_64
> library is compiled to 64 bit
> FreeBSD 9.1-STABLE amd64
> 
> Best regards,
> Marc 
> 

-- 
Marc Santhoff <M.Santhoff at web.de>