Re: [Qemu-devel] [PATCH v10 5/8] module: implement module loading

[Paolo Bonzini]

Il 17/09/2013 07:40, Richard Henderson ha scritto:
> On 09/16/2013 06:29 PM, Fam Zheng wrote:
>>> Link spice-qemu.char.so against spice-core.so.  The DT_NEEDED entry will be
>>> recorded, and ld.so will do the right thing.
>>>
>>> Anything else sounds way too much like Not Invented Here.
>>>
>> How to do the symbol checking as above if spice-core.so is automatically 
>> loaded
>> by ld.so?
> 
> You're checking the version stamp in spice-char.so.  I'd think that's good
> enough.  No need to transitively check.
> 
>> And we will need to add $moddir to LD_LIBRARY_PATH and lose the restriction 
>> of
>> modules directory too.
> 
> Or add DT_RUN_PATH to the main executable, or even add DT_RUN_PATH to the
> module itself.  In particular, link the module with
> 
>   -Wl,--enable-new-dtags -Wl,-rpath,'$ORIGIN'
> 
> and dependencies for the module will automatically be looked for in the
> directory in which the module is found.  Which is almost certiainly the only
> thing that we want -- all modules in the same directory.

This is not portable.

It looks like it can be emulated on Windows using LoadLibraryEx with the
LOAD_WITH_ALTERED_SEARCH_PATH flag and passing an absolute path to the
shared library.

But on Mac OS X a bundle (module loaded with dlopen) cannot have a
dependency on another bundle, afaik.

Paolo